Chapter XXXV.—WOOD WORKING MACHINERY.

The machines employed in wood working may be divided into 7 classes as follows:

1. Those driving circular saws.

2. Those driving ribbon or band saws.

3. Those driving boring or piercing tools.

4. Those employing knives having straight edges for surfacing purposes and cutting the work to thickness.

5. Those employing knives or cutters for producing irregular surfaces upon the edges of the work.

6. Those employed to produce irregular surfaces on the broad surface of work.

7. Those employed to finish surfaces after they have been acted upon by the ordinary steel cutting tools.

CIRCULAR SAWS.

The thicknesses of circular saws is designated in terms of the Birmingham wire gauge, whose numbers and thicknesses are shown in [Fig. 3078], where a Birmingham wire gauge is shown lying upon two circular saws, which show the various shapes of teeth employed upon saws used for different purposes.

Fig. 3078.

The teeth numbered 1 are for large saws, as 36 inches in diameter, to be used on hard wood. Numbers 2 and 5 are for soft wood and a quick feed. Numbers 3 and 4 are for slabbing or converting round logs into square timber. Number 6 is for quick feeds in large log sawing. Numbers 7, 8, 9 and 10 are for bench saws, or, in other words, saws fed by hand or self-feeding saws. Number 8 is known as the “London Tooth,” because of being used in London, England, on hard and expensive woods. Number 9 is the regular rip-saw tooth for soft woods. Number 10 is the Scotch gullet tooth. Number 11 is for either cross-cutting or rip sawing by circular saws used on soft woods. Number 12, is for large cross-cut saws; the flat place at the bottom of the tooth prevents the teeth from being unnecessarily deep and weak. Number 13 is for cross-cutting purposes generally. Number 14 is for rip sawing on saws of small diameter. It is also used for tortoise-shell, having in that case a bevel or fleam on the front face, and no set to the teeth.

The following table gives the ordinary diameters and thicknesses of circular saws and the diameters of the mandrel hole:

Diameter.Thickness.Size
Mandrel
Hole.
4 inch. 19 gauge. 3⁄4
5„19„ 3⁄4
6„18„ 3⁄4
7„18„ 3⁄4
8„18„ 7⁄8
9„17„ 7⁄8
10„16„1
12„15„1
14„14„11⁄8
16„14„11⁄8
18„13„11⁄4
20„13„15⁄16
22„12„15⁄16
24„11„13⁄8
26„11„13⁄8
28„10„11⁄2
30„10„11⁄2
32„10„15⁄8
34„9„15⁄8
36„9„15⁄8
38„8„15⁄8
40„8„2
42„8„2
44„7„2
46„7„2
48„7„2
50„7„2
52„6„2
54„6„2
56„6„2
58„6„2
60„5„2
62„5„2
64„5„2
66„5„2
68„5„2
70„4„2
72„4„2

Circular saws are sometimes hollow ground or ground thinner at the eye than at the rim, to make them clear in the saw kerf or slot with as little set as possible, and therefore produce smooth work while diminishing the liability of the saw to become heated, which would impair its tension. They are also made thicker for a certain portion of the diameter and then bevelled off to the rim.

This is permissible when the work is thin enough to be easily opened from the log by means of a spreader or piece that opens out the sawn piece and prevents it binding against the saw.

Fig. 3079.

The shingle saw, shown in [Fig. 3079], is an example of this kind, the saw bolting to a disc or flange by means of countersink screws.

Fig. 3080.

The concave saw shown in [Fig. 3080], is employed for barrel heads. The three pieces for a barrel head are clamped together and fed in a circular path, so that the saw cuts out the head at the same time that it bevels the edge.

The advantage of the circular saw lies mainly in the rapidity of its action, whether used for ripping or cross-cutting purposes. In order, however, that it may perform a maximum of duty, it is necessary that the teeth be of the proper shape for the work, that they have the proper amount of set, that they be kept sharp, and that the tension of the saw is uniform throughout when running at its working speed.

The centrifugal force created by the great speed of a circular saw is found to be sufficient to cause it to stretch and expand in diameter. This causes the saw to run unsteadily unless it is hammered in such a way as to have it rim bound when at rest, leaving the stretching caused by the centrifugal force to expand the saw and make its tension equal throughout. The saw obviously stretches least at the eye, and the most at its circumference, because the velocity of the circumference is the greatest, and the amount of stretch from the centrifugal force is therefore the greatest.

It is obvious that the amount of centrifugal force created will depend upon the speed of the saw, and it therefore follows that the hammering must be regulated to suit the speed at which the saw is to run when doing cutting duty, and in this the saw hammerer is guided solely by experience.

A circular saw may have its tension altered and impaired from several causes as follows:

1. From the saw becoming heated, which may occur from the arbor running hot in its bearings, or from the work not being fed in proper line with the saw.

2. From the reduction in diameter of the saw by frequent resharpening of the saw, this reduction diminishing the amount of centrifugal force generated by the saw, and therefore acting to cause the saw to become loose at the eye.

3. From the saw teeth being allowed to get too dull before being sharpened, which may cause the saw teeth to heat, and thus destroy the tension.

4. From stiffening the plate at the throats of the teeth when gumming the saw, an effect that is aggravated by using a dull punch.

5. From the saw teeth having insufficient set, and thus causing the saw to heat.

The methods of discovering the errors of tension in a saw, and the process of hammering to correct them, have already been explained with reference to the use of the hammer on pages from [68] to [70] of volume 2 of this work.

Before hanging a saw on a mandrel, it is necessary to know that the mandrel itself runs true in its bearings or boxes. In a new machine this may be assumed to be the case, but it is better to know that it is so, because if the mandrel does not run true several very improper conditions are set up. First, the saw will run out of true circumferentially, and therefore out of balance, and the high side of the saw will be called upon to do more cutting duty than the low side. Second, the centrifugal force will be greatest on the high side, and the saw will be stiffer, thus setting up an unequal degree of tension. Third, the saw will run out of true sideways, cutting a wider kerf than it should, thus wasting timber while requiring more power to drive.

The collar on the saw arbor should be slightly hollow, so that the saw will be gripped around the outer edge of the collar, and the arbor or mandrel should be level so that the saw will stand plumb. The boxes or bearings of the arbor should be an easy working fit to the journals, and there should be little, or what is better, no end play of the arbor in its bearings.

If a saw arbor becomes heated enough to impair the tension of the saw, it has been hot enough to impair its own truth, and should be examined and trued if necessary.

The most important point in this respect is that the face of the collar against which the saw is clamped should run true, bearing in mind that if it is one hundredth of an inch out of true in a diameter of, say 3 inches, it becomes twenty hundredths or one-fifth of an inch at the circumference of a saw that is 60 inches in diameter.

In cases of necessity, a saw that wabbles from the collar face of the mandrel running out of true, may be set true by means of the insertion of pieces of paper placed between the saw and the face of the collar.

The first thing to do in testing the saw is to take up the end motion of the saw arbor, or if this cannot be done, then a pointed piece of iron or wood should be pressed on the end of the mandrel so as to keep it from moving endways while the saw is being tested.

The saw should be revolved slowly, and a piece of chalk held in the cleft of a piece of wood should be slowly advanced until it meets some part of the face of the saw just below the bottom of the saw teeth.

As soon as the chalk has touched and the saw has made one or two revolutions the chalk should be moved a trifle farther on from the teeth, and another mark made, and then moved on again, and so on, care being taken to notice how much space there is between the high and low sides of the saw. It will be found, however, that the shorter the chalk marks are the more the saw is out of true.

A more correct method is to chalk the face of the saw and use a pointed piece of iron wire of about one-quarter inch in diameter, but in any case the saw should only be touched lightly.

The pieces of paper should be portions of rings or segments, and should extend an equal distance below the circumference of the collar, because the same thickness of paper will alter the saw more in proportion, as it is inserted farther in toward the eye of the saw.

If it should happen that two thicknesses of paper are necessary to true the saw, one should be made about half the length of the other, and the long one may extend farther in toward the eye of the saw. Thus one ring of paper may be an inch deep and the other one-half inch deep.

If but one piece of thin paper is needed, it may be simply a straight piece inserted half way down the collar and trimmed off level with the collar. In placing the paper, the middle of its length should be on that side of the saw that is diametrically opposite to the marks left by the chalk on the face of the saw.

When the saw is trued and is started it will be loose on the outside, but as its speed increases it should stiffen up so as to run true and steadily when running at its working speed.

If the saw is to be tried by actual work, it must be borne in mind that the tension of the saw must be right for its speed when in actual use, and not when running idle. If the machine has belt power enough to maintain the same speed whether the saw is cutting at its usual rate of feed, or whether it is running idle, the tension will not be altered by putting on the feed, but if the saw has been hammered to run at the full speed of the machine when not cutting and the feed is heavy enough to slacken the speed, then the tension of the saw will not be correct for its working speed.

Fig. 3081.

The eyes of small saws are either made to fit the mandrel an easy sliding fit, or else the mandrel is provided with cones to accommodate various sizes of holes, an ordinary construction being shown in [Fig. 3081], in which a is the saw arbor, fast on which is the collar b, s representing a section of the saw, w a washer or loose collar, and n the nut for tightening up w. The cone c is screwed upon a and passed through the saw until it just fills the hole, and thus holds the saw true.

In putting on the saw, it should be passed up to the collar, and c screwed home until it binds in the saw eye with enough force to bring the threads of c fairly in contact with those on the mandrel a, but if screwed home too tightly it may spring the saw, especially if the saw is a very thin one.

As c must be removed from the arbor or mandrel every time the saw is changed, the wear on its thread is great, and in time it becomes loose, which impairs its accuracy.

Fig. 3082.

This objection is overcome in the construction shown in [Fig. 3082], which is that employed by the S. A. Woods Machine Company. It is seen in the figure that the cone c fits externally in a recess in the collar b, and at the coned end also upon the plain part e of the arbor. The cone is hollow and receives a spiral spring s, s. When the saw is put on it first meets c, and as nut n is screwed up, the saw s and cone are forced along arbor e until the saw meets the face of b, and the clamping takes place. The strength of the spring s is sufficient to hold the saw true, and as the motion of cone c is in this case but a very little, therefore its wear is but little, which makes this a durable and handy device, while the saw cannot be sprung from over-pressure of the cone. Circular saws of large diameter, as from 40 inches upwards, are made a fair sliding fit upon their arbors or mandrels, and are provided with two diametrically opposite pins that are fast in the arbor collar.

The pins should be on diametrically opposite sides of the arbor, and an easy sliding fit to the holes in the saw, but they should not bind tight. Both pins should bear against the holes in the saw, and if both the pins and the holes in the saw are properly located, the saw will pass up to the collar with either side against the arbor collar, or in other words, the saw may be turned around upon the arbor.

If the pins, or either of them, bind in the holes of the saw, and the latter is forced on the arbor, it will spring the saw out of true, and when this is the case care should be taken in making the correction to discover whether it is the pins or the holes in the saw that are wrongly located. If it is the pins, the error will show the same whichever side of the saw is placed next to the arbor collar, while if the error is in the holes, the error will show differently when the saw is reversed on the arbor.

When a saw becomes worn, and its teeth require sharpening, the first thing to do is to joint it, that is to say, bring down all its teeth to the same height, which may be done by holding an emery block or file against it while the saw is running, care being taken to hold the block or file firmly, and to continue the process until the tops of the teeth run true.

The next operation is to gum and sharpen the teeth. Gumming a saw is cutting out the throats, or gullets between the teeth, so as to maintain the height of the tooth, and it follows that on saws that have sharp gullets (or in other words, saws in which the back of one tooth and the face of the next tooth join in a sharp corner), the sharpening process with the file may be made to also perform the gumming.

In the case of teeth of coarse pitch, however, this would entail too much labor in filing, and furthermore, as the height of the teeth increases with the pitch or distance apart of the teeth of circular saws, and as the higher the tooth the weaker it is, therefore coarse pitched teeth are given round gullets so as to strengthen them as much as possible. The gumming of a saw should always be performed before the sharpening, and the sharpening before the setting.

When the sharpening is to be done with the file, the cutting strokes of the file should be in the same direction as the teeth lean for the set, as this leaves a sharper cutting edge, and it follows that the proper plan is to file every other tooth first, going all around the saw, and to then turn the saw around in the vise, and file the remaining teeth.

The height of the teeth and the diameter of the saw will be best maintained by filing the front face of the tooth to bring it up to an edge, but in filing the front face the spacing of the teeth should be kept as even as possible.

If the front face has been filed until a tooth is as widely spaced as those already filed, and the edge is not brought up sharp, then the edge may be brought up by filing the back of the tooth.

Fig. 3083.

A saw gumming, gulleting or chambering machine to be operated by hand, and constructed by Henry Disston & Sons, is illustrated in [Fig. 3083]. It consists of a frame spanning the saw, and having screws b b, b b, to adjust to the saw thickness; 4 and 5 are two saw teeth, and 6 the cutter, k is a wheel for the feed screw g, and c and d gauges for regulating position and depth of the gulleting.

The cutter 6 is driven or revolved by means of the handles h h, but an important point in the construction is, that a pawl and ratchet wheel is used to drive the cutter, so that if the handles h h were revolved in the wrong direction, the cutter would not be revolved. This saves the cutter teeth from breakage. The machine is operated as follows:

Run the cutter back by means of screw g as far as necessary, then place the machine on the saw, with the cutter close up in the chamber of the tooth to be gummed.

If the teeth are regular and the same distance apart, start the cutter in any chamber; but if they are irregular, make them even by commencing in the smallest space. After gumming the saw a few times the teeth must become regular. f is a set-screw to regulate the depth of gullet. Fasten the machine to the saw by means of the screws b b, and proceed to gum the first tooth, one of the points of the star being struck at each revolution by a projection on the handle, steadily feeding the cutter until arrested by set-screw f. Remove the machine to the next tooth towards you, after having run the cutter back, and proceed as before until the whole of the teeth are gummed.

The cutter is so arranged as to slide on its axis, and when one portion becomes dull, remove a washer from back to front, and thus present a new sharp cutting surface; and so continue changing the washers until the whole face of the cutter becomes dull.

Set is given to saw teeth in two ways: first, by what is called spring set, which is applied to thin saws and to cross-cut saws; and second, swage set, which is given to thick saws and to inserted teeth. Spring set consists of bending the teeth sideways so as to cause the saw to cut a passageway or kerf, as it is termed, wide enough to permit the saw to pass through the timber without rubbing on its sides.

Swage set consists of upsetting the point of the tooth with a swage, thus spreading it out equally on both sides of the body of the saw plate, as shown at a, [Fig. 3084].

Fig. 3084.

The set of the teeth, whether given by swaging or upsetting, or by spring set, should be equal throughout the saw, so that each tooth may have its proper share, and no more, of duty to perform.

If spring set is employed, it should not extend down more than half the depth of the teeth, and this point is one of considerable importance for the following reasons. The harder the saw is left in the tempering the easier the teeth will break, but the longer they will keep sharp. Now a tooth that is hard enough to break if it is attempted to carry the set down to the root or bottom, will set safely if the set is given to it for one-half its depth only.

If a saw is to be sharpened by filing, it should be made as hard as it can be to file properly, even at the expense of rapidly wearing out the file, because the difference in the amount of work the saw will do without getting dull enough to require resharpening is far more than enough to pay the extra cost of files.

Circular saws with inserted teeth are made of thicker plate than solid saws of corresponding diameters, which is necessary in order that they may securely hold the teeth. The principal difference in the various forms of inserted teeth lies in the method of locking or securing the teeth in the saw.

Fig. 3085.

[Figs. 3084] and [3085] represent the chisel tooth saws of r. Hoe and Company. The No. 2 tooth is that used on gang edging machines and for bench work. No. 3 tooth is that used in miscellaneous sawing, for hard woods and for frozen lumber. No. 4 is the shape used in the soft and pitchy woods of southern and tropical countries.

The method of inserting the teeth is shown in [Fig. 3084] on the left, the pin wrench being shown in position to move the socket whose projection at c carries the tooth d home to its seat and locks it there.

The sockets for the numbers 3 and 4 tooth are, it is seen, provided with a split, which gives to them a certain amount of elasticity that prevents the sockets from getting loose.

Swing-frame saws are made in various forms, generally for cross-cutting purposes or cutting pieces to length.

Fig. 3086.

[Fig. 3086] represents a swing-frame saw that is mounted over a work bench, and can therefore be used without necessitating carrying the work from the bench. It consists essentially of a frame pivoted at the upper end to the pulley shaft and carrying below a circular saw driven by belt over pulleys on the upper shaft and the saw arbor. In this machine the iron hubs carrying the frame have sockets fitting over the outer diameter of the hanger hubs, so that the frame hangs upon those hubs and not upon the pulley shaft. The advantage of this plan is that the frame joint is relieved of the wear which would ensue were it hung upon the revolving spindle, while at the same time the movement of the joint is so small as to induce a minimum of abrasion. To counterbalance the frame while it is placed out of the perpendicular, there is provided a compensating weight as shown in the engraving.

Fig. 3087.

[Fig. 3087] represents an example of that class of cutting-off saw bench in which the length of the work is determined by the width apart of the saws.

This machine is constructed by Trevor and Company, and is designed for cutting barrel staves to exact and uniform lengths.

Fig. 3088.

The stave is laid upon the bars of the upright swing-frame (which is pivoted at its lower end), and the latter is vibrated by hand, which may obviously be done both easily and quickly on account of the lightness of the swing-frame and its vertical position. A dimension sawing machine, by G. Richards and Company, is shown in [Fig. 3088]. This machine is designed for general fine work, such as pattern making, and its general features are as follows:

It carries two saws (a cross-cut and a rip-saw), mounted on a frame that can be quickly revolved by a worm and worm wheel to bring either saw into position as may be required.

There is a fixed table and adjustable fence on one side of the saw, and a movable table and fence on the other.

VOL II.DIMENSION SAWING MACHINE.PLATE XVIII.
[Large
image
(100 kB).]
Fig. 3089.

The saws are ground thin at the centre, as shown in [Fig. 3089], so that but little or no set need be given to the saw teeth; hence the cutting edges of the teeth are more substantial and true, and as a result the work is cut very smoothly, and if the machine is kept in thoroughly good order, the sandpaper may follow the saw.

In [Fig. 3088], a is a substantial box frame, to which is bolted the fixed table t. t′ is the movable table which runs on rollers, and is guided by the ∧ slideway at e. This table the workman pushes to and fro by hand, the work being adjusted upon the table or to the fence, as the case may be. At w is the wheel for swinging the frame to bring the required saw into position.

In [Fig. 3089] the worm gear for swinging the saws into position is shown, and also a sectional view of one saw arbor and of the movable table. a is the main frame, and f the disc frame carrying the two saw arbors. The disc d is turned to fit a seating formed in the base, while the other end of the disc frame fits through a substantial bearing b; w′ is the worm wheel, and w′′ the worm for swinging the disc frame. The worm teeth fit closely to the worm wheel teeth, and backlash or play is prevented by means of the spring bearing shown at d, the spiral springs forcing the worm teeth into the worm wheel teeth. Thus a is the bearing for the worm carried in the box c, upon which is the spiral spring whose tension is regulated by the screw g.

The end of the worm is therefore held in a swivel joint that causes it to operate very easily.

Fig. 3090.

Fence f, [Fig. 3088] is for slitting, and is made to swing back for bevel cutting, while f′ is for cross cutting, and is adjustable for angle cutting. Fence f is fitted to a plate p, [Fig. 3090], which rests on the table top, and also rests on the long slide g. This slide fits in a beveled way h, and contains a ⊥ groove. A tongue likewise beveled fits in the top of this groove, the tongue being permanently fast to the fence plate. The ⊥ bolt passes through the tongue and fence plate, having at its upper end a milled or knurled thumb wheel r, which when tightened up fastens the fence plate and the slide together.

Upon slacking the thumb wheel r, the fence plate and ⊥ bolt may be readily shifted, setting the fence as near to gauge as possible by hand, and the thumb wheel is then tightened, and the slide (which carries the fence bodily with it) is adjusted by means of the hand wheel h and its screw which threads into a lug from the table.

The fence f is pivoted to plate p at p, and the angling link which holds it in position is secured by a hand nut m.

The front journal of the saw arbor has a double cone, and by means of the nuts n n′, [Fig. 3089], can be regulated for fit independently of the back bearing and journal, the latter being also coned and capable of independent adjustment by means of the adjustment nuts m m′.

The countershaft for driving the saw arbors is below the machine, so that the saw that is not in use remains stationary.

Fig. 3091.

Examples of the work done on this machine are shown in [Fig. 3091], the various sections shown being produced by the vertical movement of the saw through the table and the cross movement of the fence. For example, for cutting out a core box, such as shown at 6, small grooves are cut through to remove the bulk of the wood, and the saw marks at the bottom of each saw cut serve as gauge lines for the workman in finishing the circular bore with the gouge, etc.

Fig. 3092.

An example in which the table is fixed to the frame and the saw is adjusted for height above the table is shown in [Fig. 3092]. The saw arbor is here carried in a frame that is pivoted at one end to the main frame, while at the other end is a handle through which passes a locking screw for securing that end of the saw arbor frame to the arc slot shown on the main frame.

In a more expensive form of this machine an adjusting screw is used for regulating the height of the saw, and an iron table is employed instead of a wooden one.

Fig. 3093.

A double saw machine constructed by P. Pryibil is shown in [Fig. 3093]. In this machine each saw is carried in separate frames, that are pivoted at one end to the main frame and secured at the other to segments, so that either saw may be elevated to the required distance above the work table.

One saw is for ripping and the other for cross cutting, and the arbor of the latter is provided with an adjusting screw operated by the hand wheel shown on the right hand of the machine.

As the saws are on independent arbors, they can be speeded differently to suit different saw diameters, which is an advantage because, as machines of this class are for the lighter classes of work, the ripping saw will rarely be required for work of more than about 3 or 4 inches thick, and a rip saw of large diameter is not therefore necessary.

The cross cut saw however requires to be of larger diameter, as its work includes cross cutting up to 8 or 10 inches diameter, and the saw being larger does not require so high a speed of revolution.

Both saws are provided with ripping gauges and with right and left hand mitre fences, adapted to the application of either short or long work, and provided with length gauges.

Fig. 3094.

[Fig. 3094] illustrates the various gauges in place upon the table of a machine. The table is provided with a slideway, or slot, on each side of the saw, and parallel with it, and also with a slideway at one side of the table. In the figure, the mitre gauge, or gauge for sawing at an angle, is shown in two positions.

The gauge a a a is for cutting work to length, and for cropping the ends at the same time, an extension frame being used, as shown for unusually long work.

Fig. 3095.

[Fig. 3095] illustrates the method of employment of the mitre gauge. The pointer is set to the degree of angle the work is to be cut to, and is fastened to its adjusted position by the set screw h. The stop is set to the required length, and the work is held by hand against the face of the gauge, and at the same time endways against the stop, and the gauge is then moved along the slot, feeding the work to the saw. When the work is sawn and is to be withdrawn, care must be taken to keep the work fair, both against the gauge and against the stop.

Fig. 3096.

Fig. 3097.

[Figs. 3096] and [3097] show the application of the gauges for cropping off the ends of work and cutting it to exact length. There are two stops, s and t, each of which is secured in position by a set screw, and has a tongue that may be thrown over, as occasion may require—thus, suppose it is desired to merely crop off the end of the work—and both stops may be set for the work to rest against as in [Fig. 3096], and the end of the work may be cut off or cropped to square it or remove a defective part. Stop s may then be thrown over as in [Fig. 3097], and the squared or cropped end of the work rested against stop t, to gauge the length to which the work will be cut. This is a simple and convenient method of cropping and gauging.

Fig. 3098.

[Fig. 3098] represents a circular saw machine, constructed by the Egan Company, in which the table is carried on a vertical slide, and may be raised or lowered by means of the hand-wheel, bevel gears, and screw shown, and may be set at any required angle to the saw for cutting bevels.

The saw arbor or mandrel is carried by the main frame, and is therefore rigidly held.

The fences can be used on either side of the saw, which is very convenient when the table sets out of the level.

BEVEL SAWING MACHINE OR COMBINATION MITRE SAWING MACHINE.

In this machine, which is shown in [Figs. 3099], [3100], and [3101], the construction permits of the saw being set so as to revolve at other than a right angle to the work table, which is rigidly secured to the frame of the machine.

[Fig. 3099] is a general view, while [Figs. 3100] and [3101], are sectional views of the machine.

This machine is constructed by J. S. Graham & Company, and its action may be understood from the following:

Fig. 3099.

The table is firmly bolted to the frame, and is fitted with the necessary groove slides and fences for rip sawing and cross cutting. It is also provided with a removable piece, which allows the use of wabbling saws, dado heads, etc.

Fig. 3100.

The sides of this machine a, a, [Fig. 3099], are cast with an extension for countershaft. Referring now to [Figs. 3100] and [3101], the upright piece i, i, with arms b b, and g, g, is bolted to the frame as shown. The arbor frame m, m, is gibbed to t, t, by the circular piece u, and is moved to any angle by the hand wheel z, which operates the worm w, which in turn moves the arbor frame m, m. This arrangement does not require any locking device to hold the saw in position. As the centre upon which the arbor swings is in the intersection of the planes of the saw and table top, the opening in the table needs not be larger than for the ordinary saw. When cutting a mitre the saw takes the position j, [Fig. 3101]. When cutting at a right angle the saw takes the position j′ and the arbor takes the position p′ n′.

Fig. 3101.

The saw arbor can be raised and lowered by the use of the hand wheel which operates the screw b ([Fig. 3100].)

There is an accurate index located in front of the machine in sight of the operator, marked from 0 to 45°.

The iron table is of one piece 4 feet by 3 feet and fitted with the necessary groove slides for ripping and cross cutting gauges. It is also provided with removable piece e, [Fig. 3101], allowing the use of dado head, etc. The table is provided with a bevel slitting gauge s′, and cross cut or mitering gauge x′, [Fig. 3099], which in connection with the angular adjustment of the saw enables the operator to get every conceivable plain or double mitre ever required. The pulleys a′, b′, are made wide to allow the belt to travel as the saw is inclined. The pulley b′ takes up the slack of the belt. The countershaft and tightener are a part of the machine and can be run wherever a belt can be brought to them.

ROLL FEED CIRCULAR SAWS.

Figs. from [3102] to [3105] represent a roll feed circular saw, by J. Richards.

[Fig. 3102] is a side elevation, [Fig. 3103] a plan, and [Fig. 3104] a cross-sectional view through the rolls.

Fig. 3102.

In [Fig. 3102], p is the saw-driving pulley, t a stand for carrying the saw guides a, b, c, d, which are adjustable for height by means of the arm whose set screw is shown at u; at w is the spreader for opening out the board after it has been cut by the saw, and thus prevent its binding against the saw and heating it.

The construction of the feed motion is shown in [Figs. 3103], [3104], and [3105].

On the saw arbor is the feed cone c, [Fig. 3103] having four steps so as to give four rates of feed. This cone connects by belt to feed cone d, whose shaft drives feed pulley e, which drives f by belt connection. f drives two worms shown by dotted lines at h and i, and these drive the worm wheels which drive the feed rolls, one of these worm wheels being shown at k, in the side view, [Fig. 3102].

Fig. 3103.

The feed roll l ([Fig. 3103]) is supplemented by a fence or gauge face p, which guides the work closer up to the saw than would be possible with a roll, and a supplemental roll is provided at m, thus affording a guiding surface for the work from m to the end of p. The stand for guide roll l fits in a slideway, and is adjustable along it by means of the screw s. Similarly the stand for roll n is fed along its slideway by screw r. There are three separate sets of saw guides, all of which are shown in the plan view [Fig. 3103], and of these the top ones, a, b, c, d, e, f, g, and h are adjustable by nuts. The front ones, l, m, n, o, p, q, and the back ones, i, j, k, and r, s, t, are adjustable by means of the wedges w. At z is a wedge for adjusting the spreader w so as to keep it close to the saw whatever the diameter of the latter may be.

Fig. 3104.

Fig. 3105.

[Fig. 3105] is an end view of the machine showing the feed worms h and i, and the belt tightener v, which is carried on the arm u on whose shaft is the weight y, attached to which is the handle x.

SEGMENTAL CIRCULAR SAWS.

A segmental circular saw is one in which the saw is composed of segments secured by screws to a disc, the construction being such as shown in [Fig. 3106], in which a is the saw arbor, d the disc, and e, f, g, h, i, j, etc., the segments.

Fig. 3106.

The segments are made of varying thicknesses at the cutting edge, and are tapered for a distance for from 6 to 8 inches inwards from the teeth points. Thus in the figure there is shown at p an edge view of a segment, from a to b being parallel, and from b to c being ground off taper.

The segments are held to the disc by the two sets of screws, r, s, and are further secured at their edges by pieces of copper, as shown at w. Between the edges of the segments there is left a space or opening of about 1⁄16 inch, which is necessary to insure that the segments shall not bind together edgeways, as that might prevent their seating fairly against the face of the disc d.

The seats for these pieces of copper are shaped as shown in the face views at w, and in the edge views at w′, the mouth of the slot being widened on each side, so that riveting up the pieces of copper will prevent the segments from moving sideways.

In fitting in these pieces of copper, it is essential to take care that they do not completely fill the slots, but leave a small opening at each end of the slot, as at f and g in the figure, and in order to do this the copper must be left about 1⁄8 inch narrower than the width of the slot.

If the copper is, in riveting up, brought to bear against the end of the slot, it will twist the segments out of line one with the other, causing the saw to drag, cut roughly and produce bad work.

Left-Hand. Right-Hand.

Fig. 3107. Fig. 3108.

[Figs. 3107] and [3108] represent portions of segmental saws for cutting veneering. In some of these saws the screw holes are so arranged that the segments can be moved out to maintain the diameter of the saw as it wears.

GANG EDGING MACHINES.

For dressing the edges of planks parallel and to width what are called gang edgers or gang edging machines are employed.

A gang edger consists of an arbor driving two or more circular saws, through which the boards to be edged are fed. Means are provided whereby the distance apart of the saws may be rapidly adjusted while the saws are in motion, so that if a board will not true up to a given width, the saws may be set to cut it to a less one without delay.

Fig. 3109.

[Fig. 3109] represents a self-feeding gang edger, constructed by J. A. Fay & Company, and in which the left-hand saw may be fixed at any required position on the left-hand half of the saw arbor, while the two right-hand ones may be adjusted independently along the arbor, while the machine is running.

At the back of the saw is a feed roll, and above it a pressure roll, whose pressure may be regulated by means of the weight and bar shown at the back of the machine. The object of placing the feed and pressure rolls at the back of the saws, is, that if a board is found to be too narrow for the adjustment of the saws, it may be withdrawn without stopping or reversing the machine, and the saws may be drawn together sufficiently to suit the case.

[Fig. 3110] is a plan and [Fig. 3111] an edge view of the work table, and show the means of adjusting the saws. a is the saw arbor, and 1, 2, 3, the circular saws. Saw 1 is carried by the sleeve b, which is secured in its adjusted position by the set screw c.

Fig. 3110.

Fig. 3111.

The mechanism for traversing saws 2 and 3 corresponds in design, and may be described as follows:

The arbor a has a spline s to drive the sleeves d, d′, which hold the saws and are carried by arms e, e′, which operate in slideways and have racks f, f′, into which gear pinions whose shafts g, g′, are operated by the hand wheels h, j.

It is obvious that by means of the hand wheels h, j, saws 2 and 3 may be regulated both in their distances apart or in their distances from saw 1, while the machine is in full motion, the bushes or sleeves d and d′ being carried by and revolving in the slide pieces or sliding bearings e and e′ respectively. Now suppose that e′ be moved to the left by hand wheel j, until it abuts against the end of d, at the slide end, and a further movement of d′ will also move d, causing it to operate its pinion and revolve the hand wheel h, hence d and d′ may be simultaneously moved without disturbing their distances apart by operating hand wheel j. On the yoke above the saws is a coarse-figured register plate to enable the setting of the saws to accurate widths apart.

RACK FEED SAW BENCH.

This machine is employed for the purpose of reducing balks or logs into planks of any thickness required. The machine is fixed on the floor of the saw mill, all the gearing being underneath the floor, so that the table may be set level with the floor, which is a great convenience when heavy logs are to be operated upon. The machine consists of a substantial bed plate or frame a, [Fig. 3112], carrying the saw and the feed works. The carriage runs on rollers, some of which are fixed to the frame a, and others to the framing timbers b, which are long enough to support the carriage throughout its full length, when the carriage is at either end of its traverse.

VOL. II.RACK‑FEED SAW BENCH.PLATE XIX.
[Large
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Fig. 3112.

The driving pulley for the saw arbor is shown at c, [Fig. 3112], in dotted lines and in [Fig. 3113] in full lines. Upon the saw arbor is a cone pulley d, [Fig. 3113], for operating the carriage to the feed, the construction being as follows:

Fig. 3113.

Referring to [Figs. 3112] and [3113], cone pulley d connects by a crossed belt to cone pulley e, on whose shaft is a pulley e which drives the pulley f, on whose shaft is the pinion f, which drives the gear g. On the same shaft as g is a pinion g, which drives the gear wheel h, which engages the rack j, on the carriage, and feeds the carriage to the cut. The diameters of pulleys e, f, and of f, g, and g, are proportioned so as to reduce the speed of the cone pulley d, down to that desirable for the carriage feed. But, as there are four steps on the cones d, e, therefore there are four rates of cutting feed or forward carriage traverse, which varies from 15 to 30 feet per minute.

The speed of the saw varies in practice, some running it as slow as 9,000 feet per minute at the periphery of the saw, and others running it as high as 16,000 feet per minute. The latter speed however, is usually obtained when the saws are packed with fibrous packing, which will be explained presently.

The quick return motion for the carriage is obtained as follows:

Referring to [Figs. 3113], and [3114], k is a fast and k′ a loose pulley on the shaft k, and receiving motion by belt from a countershaft.

The speed of the fast pulley k is such as to give a return motion to the carriage of about 50 or 60 feet per minute, being about twice as fast as the carriage feed motion.

We have now to explain the methods of putting the respective carriage feed motions into and out of operation, and insuring that both shall not be in gear at the same time.

Fig. 3114.

Referring therefore to [Figs. 3113] and [3114], suppose the carriage to have completed a feed or cutting traverse, and the operator pushes with his knee the lever or handle h, [Fig. 3114], which revolves shaft m, on which is an arm that moves the belt-shifting rod n, thus moving the belt from fast pulley f to loose pulley f′, thus throwing the feed gear out of engagement and causing the carriage to stop. He then presses down the foot lever l, [Fig. 3113], which operates the belt-shifting rod p, [Fig. 3114], and moves the belt from loose pulley k′, to fast pulley k, which having a crossed belt, operates the pulley f in the reverse direction and traverses the carriage backwards, or on the return motion.

Upon releasing the foot from the lever l, the weight w operates the foot lever l, and the belt is re-shifted from fast pulley k to loose pulley k′, and the carriage stops.

The carriage is formed of iron plates with an open space of about 1⁄2 inch between them, as shown in [Fig. 3114], this space forming a race to permit the carriage to travel past the saw. The only connection between the two sections or parts of the table, is a wide plate at the rear end which secures them together, and causes the lighter portion of the table, which is merely driven by the friction of the rollers c, to always travel with the lower or under portion, which is driven by the rack j. In larger machines for the heaviest work, both sections are driven by a rack motion.

The guide motion for the carriage is constructed as follows:

a, a, are brackets placed at intervals along the whole frame work.

These brackets support rollers c, which have flanges on them to prevent any side motion of the carriage, the construction being most clearly seen in [Fig. 3113]; b being a bearing for the shaft v of the rollers. Each section of the carriage, it will be seen, has two ribs or ways which rest on the rollers, which are arranged four on each shaft v (i.e. two for each section of the carriage).

The fence or gauge against which the face of the work runs is very simply arranged as is shown in [Figs. 3113], and [3114], being secured to the shaft q, by a long bolt t, threaded into the top of the fence, and at its lower end abutting against a shoe fitting partly around the top of the shaft q. It is squared at the top to receive a wrench or handle u, and it is obvious that unscrewing the handle releases the fence from shaft q, so that the fence may be moved rapidly by hand across the table to approximate the adjustment of the fence from the saw. The fence having been thus approximately adjusted, and locked to the shaft by means of the handle u, the final adjustment is made by means of the hexagon nut w, on the bed of the shaft nut x, serving as a lock nut, to hold q in its adjusted position.

Fibrous Packing.—The fibrous packing before referred to is composed of hemp, plaited in a four strand plait and inserted in an open-top trough, along the sides of the saw for a distance about two inches less than the radius of the smallest saw the machine uses.

This packing steadies and stiffens the saw, and also affords a means of adjusting its tension, while the saw is running.

Suppose for example, that the saw is rim bound,[47] and the fibrous packing may be rammed tightly to the saw, as near to the saw rim as possible, and less tight as centre of the saw is approached.

[47] For the principles involved in hammering saws to equalize the tension see [page 69 (Vol. II.)] et seq.

This warms the saw, but makes it warmer at the circumference than at the centre, expanding the circumference, and by equalizing the tension, enables the saw to run straight.

Fig. 3115.

When the packing is to be adjusted, the carriage is run out of the way, and the packing operation is performed by hand, with a caulking tool. The packing and its box, as applied to a rack saw bench is shown in [Fig. 3115], by the dark rectangles. By thus packing the saw to guide it and keep it straight, thinner saws may be used, saws 52 inches in diameter, and having a thickness of but 7 or 8 gauge being commonly employed, and in some cases of 9 gauge.

Saws that are thus packed, produce much smoother work.

The packing, it may be observed, is kept well lubricated with oil, and the following is the method of adjusting it.

The side of the saw on which the operator stands is the last to be packed, the packing on the other side being inserted so as bed fairly but lightly against the saw, so as not to spring it, which may be tried with a straight-edge. The packing on the other side is then inserted to also bed fairly against the saw, without springing it, and the saw is run until it gets as warm as it may, from the friction of the packing. If, then, the saw flops from side to side, the outside (circumference) is loose, and the packing is rammed together on both sides of the saw and near the saw arbor or mandrel, care being taken that in ramming the packing the saw is not unduly pressed on either side.

Expert sawyers generally change the packing when the saw is changed, and thus keep for each saw its own packing. The slot or pocket in which the packing lies is about 11⁄4 inches deep, and 1⁄2 inch wide.

Fig. 3116.

In ordinary circular saw benches or machines the packing comes about up to the level of the table, as shown in [Fig. 3116], in which a is a hand hole for putting in and lifting out the plate b, so as to put in or remove the wooden pieces c, d, upon which the packing rests.

VOL. II.PLANTATION SAW MILL.PLATE XX.
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(225 kB).]
Fig. 3117.

[Fig. 3117] represents a saw mill constructed by the Lane & Bodley Company. In this machine two circular saws are employed, the upper one being of small diameter and revolving in the same direction as the log feed. a is the driving pulley for the main saw arbor a, and b the driving pulley for the upper saw arbor b. The carriage feed is obtained by belt from cone pulley c to cone pulley d, on whose shaft is a friction pulley e, which, for the feed motion, is moved by lever e into driving contact with pulley f, whose shaft drives the pinion g, which gears with the rack of the carriage. The three steps on the cones c, d, give three rates of feed, and a quick return motion is given to the carriage by engaging the friction pulley with a wheel not shown in the engraving.

The log to be sawn rests upon the slideway s s’, and is secured thereon by the dogs j, j, which are capable of sliding up or down upon the heads h, h′. When the handles k are raised the slides carrying dogs j are free to be moved up and down h, h′, whereas when handles k are depressed the dogs j are locked and hold the log. The operation is to raise the dog slides to the top of h, h′, set the log up to the faces of h, h′, and then by raising handles k, let the dog slides fall, their weight forcing the dogs into the log, and the depression of k locks the dog slides upon h, h′, respectively.

The log feed is obtained from the lever l, which operates the ratchet wheel t, which drives bevel gears v and w, which operate the screws that slide the heads h, and h′, along the slideways s and s′.

Three rates of log feed are obtained by regulating the amount of motion that can be given to the lever l, the construction being as follows:

In the lever l is a slot in which a stop r can be secured at different heights, and the piece m has four notches. The limit to which l can be moved to the left is until it comes against the stop x, but the limit to which it can be moved to the right is governed by the height of the stop r in the slot in l. If stop r is set at its highest position in the slot, l can be moved to the right until the stop r meets the right hand step on the circumference of m, and a maximum of log feed is given.

TUBULAR SAW MACHINE.

Fig. 3118.

[Fig. 3118] represents a tubular saw machine. The saw runs in fixed bearings, the work feeding on the table b, running on ways on a. The work is here obviously sawn to a curve corresponding to that of the circumference of the saw.

CROSS CUTTING OR GAINING MACHINE.

In [Figs. 3119] and [3120] is represented a machine constructed for either cross cutting or gaining, the gaining head shown on the machine being replaced by a cross-cut saw when cutting off is to be done.

Fig. 3119.

It consists of a vertical column or standard, upon the face of which a slideway a for the arm b, on which is a slideway c, along which the head for carrying the saw arbor traverses.

VOL. II.GAINING OR GROOVING MACHINE.PLATE XXI.
Fig. 3120.
Fig. 3121.

When the saw is to be used, the carriage or work table must be locked in position and adjusted so that the saw will come fair in the groove, provided in the table, but it is not necessary to dog or fasten the work to the table, because the saw itself draws the work over fair against the fence.

When the machine is used for gaining, the work must be dogged fast to the table, so that the work and table may be moved accurately together and the widths apart of the gains kept accurate.

Joshua Oldham’s combination saw for grooving or gaining is shown in [Fig. 3121]. It consists of two outside saws, such as shown at the top of the figure, and having spur teeth between the ordinary cutting teeth. The tops of the spur or cross-cutting teeth are a little higher than the other teeth, so that they sever the fiber before the ordinary teeth attempt to remove it, and thus produce very smooth work. The inside pieces, shown at the bottom of the figure, go between the two outside saws, if necessary, to make up the required width of gain. They are made 1⁄8 inch thick, with an odd one 1⁄16 inch thick, and will thus make gains advancing in widths by sixteenths of an inch.

SCROLL SAWING MACHINES.

The scroll sawing machine derives its name from the fact that it is particularly fitted for sawing scroll or curved work by reason of the saw (which is a ribbon of steel with the teeth cut on one edge) being very narrow.

The principal points in a scroll sawing machine are to have the saw held under as nearly equal tension as possible throughout the whole of the stroke; to render the machine readily adjustable for different lengths or sizes of saws, to provide it with means of taking up lost motion, and to avoid vibration when the machine is at work.

Fig. 3122.

Fig. 3123.

A scroll sawing machine constructed by the Egan Company is shown in [Fig. 3122], a sectional view of the saw straining mechanism being shown in [Fig. 3123]. a, a, is a casting having slides for the head b, which is adjustable upon a to suit different lengths of saws, and is secured in its adjusted position by the bolt c and nut d. To the ends of the springs s, a strip or band of leather is secured, the other end passing around the small step f of a roller r, and being secured thereto. The roller r is so supported that it may rise and fall with the strokes of the saw. A second leather band g is secured at t, passes over the large step of r, and at its lower end hooks to the saw, which is strained by the springs s. This reduces the motion of the springs, and thus serves to equalize their pressure throughout the saw stroke.

The lower end of the saw is gripped in a slide or cross-head that is driven by the connecting rod and crank motion shown in the general view [Fig. 3122]. The lever shown at the foot of the machine moves the belt to the fast or loose pulley to start or stop the machine, and operates a brake to stop the machine quickly.

Fig. 3124.

[Fig. 3124] represents a scroll saw constructed by H. L. Beach. This machine is provided with a tilting table, which can be set at any angle up to 39 degrees, either to the right or left, the exact angle being indicated by a graduated arc.

The straining device, including the springs, air pump, guide-ways, cross-head and steel bearing, are all attached to the vertical tubular shaft, which is secured to the heavy cast back support by the box e and eccentric lever f. By raising the lever f, the shaft, being balanced, is free to move up or down to suit any length of saw.

At the same time, the steel bearing l forms a support for the back and sides of the saw, and can be raised or lowered to suit any thickness of work.

The under guide-ways are so constructed that their expansion by tightening does not tighten the cross-head. Instead of the ordinary tight and loose pulleys, the crank shaft carries a friction pulley and combination brake by which the saw is stopped or started instantly, by a single motion of the foot.

This leaves the hands entirely free, and saves considerable time in stopping and starting.

The lower end of the saw is held by a steel clamp; when the saw breaks it can be used again by filing a notch. Both ends of the saw are arranged to take up lost motion and wear.

Any desired strain from 10 to 75 pounds can be given to the saw, and the strain is equal at all points of the stroke.

BAND SAWING MACHINES.

Fig. 3125.

The simplest form of band sawing machine is that in which the work is fed to the saw by hand, a machine of this class, constructed by J. A. Fay & Co., being shown in [Fig. 3125]. It consists of a standard or frame a, carrying the saw-driving wheel b, and the upper wheel c, the saw being strained upon these two wheels. The lower wheel runs in fixed bearings, while the bearing of the upper wheel is carried in a slide provided in the frame, being operated in the slide by a screw, whose hand wheel is shown at e, so that it may be suited for different lengths of saws.

The bearing of the upper wheel is so arranged that the tension placed on the saw may be governed by a weighted lever f, which enables the upper bearing to lower slightly, so that if a chip should fall between the saw and the lower wheel, it may not overstrain, and therefore break the saw.

At j, is a bar carrying a guide g, which sustains the saw against the pressure of the cut, a similar guide being placed below the table t, at g′. This latter guide is fixed in position, whereas the upper one, g, is adjustable for height from the work table, so that it may be set close to the top of the work, let the height of the latter be what it may. g′′ is a guide and shield for the saw at the back of the machine, and h is a shield to prevent accident to the workman, in case the saw should break.

Band saws are ribbons of steel, brazed together at their ends and having their teeth provided on one edge. The widths of band saws vary from 1⁄16 inch to 8 inches, and their thicknesses from gauge 18 to 22 gauge, according to width.

The advantage of the band saw lies in that it may be run at high velocity, may be made thin, and its cutting action is continuous.

As a band saw is weak, it is desirable to have the teeth as short as possible and leave enough room for the sawdust, so that it shall not pack in the teeth.

Fig. 3126.

In a circular saw, the centrifugal force acts to throw the sawdust out, while in a frame saw, the backward motion of the saw acts to clear the teeth of the dust, whereas in a band saw the dust is apt to pack in the teeth while they are passing through the work. The remedy is to space the teeth widely, thus giving room for the dust without having a deep tooth, an ordinary form of tooth being shown in [Fig. 3126].

Fig. 3127.

A stronger form of tooth is shown in [Fig. 3127], the tooth gullets being well rounded out, and the teeth shallow at the back, while having ample room in front for the dust.

Fig. 3128.

In determining the shapes of the teeth of band saws, we have the following considerations:

One of the principal objects is to have the back edge of the saw bear as little as possible upon the saw guide, and as the feed tends to force that edge against the guide, we must so shape the teeth as to relieve the back guide as much as the circumstances will permit. This may be done by giving to the front faces of the teeth as much rake as the nature of the work will permit. Thus, in [Fig. 3128], it will be seen that from the front rake, or hook of the teeth, as it is commonly called, there is a tendency for the cut to pull the saw forward, this tendency being caused by the pressure, on the teeth in the direction of the arrows, and obviously acting to prevent the saw from being forced against the back guide.

For sawing soft woods, such as pine, the teeth may be given a maximum of front rake or hook, whereas for hard woods, the front faces must be made to stand at very nearly a right angle to the length of the blade, and the feed must therefore be lighter, in order to relieve the back edge of the saw from excessive contact with the back guide, which would not only rapidly wear the guide, but acts to crystallize the edge of the saw and cause it to break.

Fig. 3129.

The set of the teeth of band saws is given in two ways, i. e. by spring set, which consists of bending each alternate tooth sideways, as in [Fig. 3129], or by swage set (upsetting or spreading the points of all the teeth), a plan that may be followed with advantage for all saws thicker than about 20 gauge.

Spring set is given either by bending, or by hammer blows, and swage set either by blows or by compression. In spring set, each tooth cuts on one side, and there is consequently a pressure tending to bend the tooth sideways, and break it at the root, whereas in spread set, the tooth cuts on both sides equally. As the front faces of band saw teeth are filed straight across, as in [Fig. 3129], and are not given any fleam for any kind of woodwork, the set, whether spring or a spread, should be equal in amount for every tooth, and the pitch and depth of the teeth should be exactly alike, so that no one tooth will take more than its proper share of the cut.

The bend or set of the tooth in spring set saws, should not extend more than half way down the depth of the tooth, which will make the set more uniform and save tooth breakage, it being borne in mind, that a tooth hard enough to break if the set extends down to the root, will set easily if it extends half way down only, and that a saw may be soft enough to file, and of a proper temper, and yet break if the spring set is attempted to be carried too far down the tooth.

Fig. 3130.

If as in the case of fine pitched teeth, the teeth are filed with a triangular or three square file but little front rake or hook can be given, without pitching the teeth widely. This is shown in [Fig. 3130], in which s, is the section of a saw, and f, a section of a three square file. The front faces have no rake, and the file is shown as acting on both faces.

Fig. 3131.

In [Fig. 3131], we have the same pitch of teeth, but as the file is canted over, so as to give front rake or hook to the tooth, the tooth depth is reduced, and there is insufficient room for the sawdust. In order, therefore, to give to the teeth front rake, and maintain their depth while keeping the pitch fine, some other than a three square file must be used.

The principal defect of the band saw is its liability to break, especially in band saws of much width, as say 3 inches and over. A saw that is 6 inches wide will ordinarily break by the time it has worn down to a width of 4 inches. Now for heavy sawing it is necessary that wide saws be used, in order to get sufficient driving power without over-straining the saw.

Fig. 3132. Fig. 3133.

The causes of this saw breakage are as follows:

In order that the saw may be regulated to run on the required part of the upper wheel, and lead true to the lower wheel, it is necessary that the upper wheel be canted out of the vertical, and band sawing machines are provided with means by which this may be done. If the upper wheel were set level, as in [Fig. 3132], the saw itself would be held out of level, and the toothed edge would be more tightly strained than the back edge. Furthermore the middle of the saw cannot bed itself perfectly to the wheel. Furthermore, the velocity of the toothed edge would be greater than that of the back edge because of its running in a circle of larger diameter when passing over the wheels.

This is to some extent remedied by setting the wheel out of the vertical, as in [Fig. 3133], in which case the two edges will be more equally strained, and have a more equal velocity while passing over the wheels.

There will still however, be an unequal strain or tension across the saw width, and it is found that unless the saw is made what is known as loose,[48] it is liable to break, and will not produce good work. It is to be observed however, that the above may be to a great extent, and possibly altogether, overcome by means of having the rim face of the wheel, or of both wheels, curved or crowned in their widths, so that the saw will be in contact with the face of the wheel, nearly equally across the full saw width. This would also cause the saw to run in the middle of the wheel width, and thus enable the alignment of the saw to be made without requiring the upper wheel to be set out of level.

[48] See [page 69, Vol. II.], for what is technically known as looseness in a saw.

RE-SAWING BAND SAW MACHINE.

A re-sawing machine is one used to cut lumber (that has already been sawn) into thinner boards. [Fig. 3134] represents a band saw machine, constructed by P. Pryibil, having a self-acting feed motion, consisting of four feed rolls, all of which are driven, and two small idle rolls, which are so arranged as to guide the last end of the stuff or work after it has left the driven rolls.

Fig. 3134.

Four rates of feed are provided, and the upper wheel can be set at the required angle from a perpendicular while the machine is in motion.

The upper guide wheel, and the mechanism by which it is carried, is counterbalanced by a weight that hangs within the column or main frame, and is therefore out of sight.

Fig. 3135.

The construction of the parts by means of which the upper wheel is adjusted in height to regulate the tension of the saw, and which also cants the wheel out of the vertical, is shown in [Fig. 3135], which represents a portion of the main frame or column, on which is a slideway b, for the slide c, which carries the bearing for the upper wheel.

The method of moving the slide c for moving the upper wheel to adjust the saw tension is as follows:

By means of the handle h and the worm and worm wheel at w, the shaft s is revolved. The upper end of s is threaded into the nut n, which is capable of end motion in its bearing at e, and which abuts against the lever l, the latter abutting against the end of the screw m, and acting at its other end on the rubber cushion p. Now suppose that s be revolved in the direction denoted by the arrow, and the effect will be to raise the nut n. This effect will be transferred through the screw m to the slide c, which will rise up on b, carrying with it the upper wheel bearing and wheel.

When the upper wheel receives the strain of the saw, then the continued revolution of shaft s will cause the nut n to lift endways in its bearing e, the screw m acting as a fulcrum to cause the lever l to compress the rubber cushion p. The amount of tension on the saw is tested by springing it sideways with the hands. Now suppose the saw to be properly strained, and that a piece or chip of wood accidentally gets between the saw and the lower wheel, and the result will be that the slide c will (from the extra strain caused by the chip) move down on its slideway b, which it is capable of doing, because the long arm of the lever l can move down, compressing p, and this will prevent the saw from breaking.

To cant the wheel for leading the saw true to the lower wheel, the following means are provided:

The upper wheel bearing rests on the fulcrum at a, and is guided sideways by the screws c and d. At f is a stud threaded into the bottom half of the upper wheel bearing, the wheels g and h threading upon f. The weight of the upper saw wheel endeavors to lift the end j of the wheel bearing, and wheel h determines how much it shall do so, while wheel g acts as a check nut to lock the adjustment.

Fig. 3136. Fig. 3137.

The feed rolls are carried in slides which are operated in slideways by means of screws, and the two back rolls, or those nearest to the column are maintained vertical. The two front ones, however, are provided with means by which they may adjust themselves to bear along the full depth of the work, notwithstanding that it may be taper. The construction by means of which this is accomplished is shown in [Figs. 3136] and [3137], in which a is front and b a back feed roll. The bearings of feed roll a abut against rubber cushions c, c, whose amount of compression is regulated by the set screws d, d.

Fig. 3138.

The construction of the saw guides is shown in [Fig. 3138], which is a plan view partly in section. s s are hardened steel plates set up to the saw by means of studs whose nuts are shown at n n. w is a friction wheel which supports the saw against the thrust caused by the work feeding to the saw. The adjustment of the wheel w to the saw is obtained by means of the wheel h.

The hand wheel h operates the screw r r, that adjusts the wheel w to the saw, the wheel j serving to lock the screw in its adjusted position.

VOL. II.BAND SAW WITH ADJUSTABLE FRAME.PLATE XXII.
Fig. 3139.

[Fig. 3139] represents Worssam’s band saw machine, in which the standard may be set at any required angle for cutting bevels.

When the work is heavy and not easily handled it is preferable to set the standard and saw at the required angle, rather than to set the table at an angle and have the saw remain vertical. In Worssam’s machine this is accomplished as follows:

a is the main frame carrying the work table t, and having circular guideways b, b′, which carry the standard c having guide c′ for working in the circular guideways b, b′.

The saw-driving wheel d, is carried in bearings provided in c, and, therefore moves when the standard c is moved.

At the upper end of c, is the slide e, which carries the bearing for the upper wheel f, this slide being adjusted to regulate the saw tension by the hand wheel o, whose screw threads into a nut in the slide e. h carries the front guide g, for the saw, the back guide g′ being carried by a bracket bolted to c. The back guide is fixed in position, but the front one is adjustable to suit the height of the work by raising or lowering it.

The means for setting the saw at the required angle to the work table are as follows:

At the back of the standard c is a rack j, whose pitch line is an arc of a circle of which the axis of the guideway c′ is the centre.

Into the rack j fits the worm wheel k, at the bottom of the shaft of which is a pair of bevel gear wheels l, which are operated by the hand wheel m.

VOL. II.BAND SAW MILL.PLATE XXIII.
[Large
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Fig. 3140.
[Large
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Fig. 3141.
[Large
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Fig. 3142.

A band saw machine constructed by Messrs. London, Berry & Orton, is shown by [Figs. 3140], [3141] and [3142], in [plate XXIII]. The saw-driving wheel d, has wrought iron arms turned true and screwed into the wheel hub. The wooden segments have their grain lengthways of the rim, and between them are placed pieces of soft wood with the grain across the rim. This acts to keep the joints tight, notwithstanding the expansion and contraction of the wood.

The upper wheel is adjusted for straining the saw, and for leading the saw true, by the following construction. It is carried in a U-shaped frame f, which is pivoted at y to a slide that is gibbed to the main frame, and by operating the screw shown at x, the frame f is set to the required level.

To regulate the tension of the saw, the hand wheel k is operated, which drives the pair of bevel gears j and i, the latter of which operates the threaded shaft h, whose upper end g connects with the slide which carries f. Within g is a spring to act as a cushion to the slide, and thus prevent saw breakage should a chip pass between the saw and its driving wheel.

The saw guide frame is secured to the main frame at m′, m′. Upon the face of m, is a slideway for the saw guide arm n, which may thus be adjusted as closely to the upper face of the work as possible.

The weight of arm n is counterbalanced by a rope passing over the pulley v, and supporting the counterbalance weight w. The feed motion is constructed as follows:

On the same shaft as the main fast and loose pulleys a, b, is the feed pulley l, which by belt connection drives pulley m, which is on the shaft w, upon which is a friction disc n, by means of which the rate of feed is regulated. The feed disc n drives the wheel o; the degree of contact between these two (n and o) is regulated by means of the weight t, on the lever u.

On the same shaft as the friction wheel o, is a pinion driving the gear x, which is on the same shaft as the pinion y, which drives the two gears y′ and y′′.

Referring now to [Fig. 3142], gear y′ drives the pair of bevel gears z and z′, for the feed roll e, and the pair of bevel gears shown at z′′, the feed roll f. The gear y′′ drives similar gearing for the feed rolls e′ and f′, seen in the plan [Fig. 3140].

Referring now to the plan [Fig. 3140], and the side elevation, [Fig. 3142], the feed roll f is carried in a frame g, which is fitted on the slideway d, d, and receives a screw i, upon which is a hand wheel h; at the back of this wheel is the lever j, which is weighted as shown, so that the force with which feed roll f grips the work is determined by the weighted lever j, and may be varied to suit the nature of the work by moving the weight along j.

The construction of the gear for feed roll f′ is similar, as may be seen in the plan [Fig. 3140], f′ being in a slide g′, which has a screw i′, and hand wheel h′, a weighted lever corresponding to j acting against wheel h′. In proportion as f and f′ are opened out to admit thick stuff or work, the hand wheels h and h′, respectively are used to screw the screws i and i′ into their respective slides g and g′, and thus maintain the weighted levers in their requisite horizontal positions. The feed rolls e and e′ are carried in slides c and c′, and are adjusted to suit the thickness of the stuff or work by a hand gearing, which consists of the hand wheel a, seen in the plan and in the front elevation, [Fig. 3141], which drives the pinions b and b′, which operate screws for the slides c and c′, the latter being a left hand screw. The front rolls e and e′ are therefore held in a fixed position, whereas the back ones f and f′ may open out under the pressure of the weighted levers j, and thus accommodate any variation in the thickness of the work.

The rate of feed is varied to suit the nature of the work by the following construction: The friction wheel o and the hand wheel r are connected by a yoke q, [Fig. 3142], at the ends of which are the joints p, q, seen in the plan, [Fig. 3140]. Hand wheel r is threaded to receive the screw s, and it follows that by revolving r, the friction wheel o may be moved towards the centre of the friction disc n, which would reduce the velocity with which n would drive o, and therefore reduce the rate of feed. If the friction wheel o be moved from the position it occupies in the plan [Fig. 3140], to any point on the other side of the centre of the friction disc n, the direction of feed motion would be reversed.

Fig. 3143.

A band saw machine for the conversion of logs into timber, and constructed by Messrs. London, Berry & Orton, is shown in [Fig. 3143]. The logs are fixed to the carriage by dogs and the carriage traverses the log to the feed.

VOL. II.LOG CROSS‑CUTTING MACHINE.PLATE XXIV.
Fig. 3144.
Fig. 3145.

Reciprocating Cross Cutting Saw For Logs.—The machine shown in [Figs. 3144] and [3145] is designed for the purpose of cutting heavy and long logs into convenient lengths preparatory to cutting the logs up in other machines, and it is usually therefore placed at the entrance to the mill, where it is of immediate service as the lumber comes into the building.

The machine here shown is intended for logs up to 36 inches in diameter, is simple in construction, requires very little foundation, is easy to handle, and occupies but very little room.

The saw is here fed mechanically to its cut, whereas in some machines it is fed by its own weight, and therefore requires great care to be taken, when the saw is finishing its cut, in order to prevent it from falling after it has passed through the log.

[Fig. 3145] is a side elevation and [Fig. 3144] a plan of the machine, in which a is the frame of the machine on which are the bearings for the shaft b carrying the fast pulley c, loose pulley d and fly-wheel e at one end, and at the other, a crank disc f, whose pin is shown at g. This drives the saw k through the medium of the connecting rod h.

The saw is fast at the butt end to along slide j, j, which works in a long guide formed on the face of the swinging frame l, which pivots at one end on the shaft b and at the other is carried by a slide p, on the vertical slideway m, and is fed down the same to give the saw its cut by the screw whose hand wheel is shown at n.

v is a second guide for the saw, and being connected to the slide feeds down with the saw until it meets the log.

A counterweight w balances the weight of the slides and saw, so that there being a pit beneath the balance weight the saw and its guides may be raised so that the saw stands out of the way when not in use. y is a dog for holding the log, which is also blocked by the wedges z z′.

Fig. 3146.

The construction of the main bearing is shown in [Fig. 3146], in which it is seen that the hub or boss of the loose pulley is much longer than that of the fast one, thus providing a large amount of bearing surface, which is advantageous because the belt will remain longer at the loose pulley than it will on the tight one. The sleeves or bushes in which the shaft runs afford a simple means of renewal to restore the fit when the shaft has worn loose in its bearings.

It is obvious that as the guide frame l is pivoted to the shaft b, it carries the end of the saw (as it is fed down) in an arc of a circle of which the axis of b is the centre, whereas the slideway m is straight, and slide p therefore moves in a straight line instead of in the required arc. Provision however is made to accommodate these two motions as follows:

Fig. 3147.

[Fig. 3147] is a sectional view of the slides on the slideway m and [Fig. 3148] a plan of the same. The hand wheel n corresponds to n in [Fig. 3145]. Upon the vertical slideway (in [Fig. 3145]) of the standard fits the slide p, which has a horizontal slideway for the slide r, which is free to slide automatically, having no screw or other device to restrain it, save the guide frame l, and therefore as this frame is lowered to feed the saw the slide r moves automatically to accommodate the arc of a circle in which the guide moves on account of being pivoted at b.

Fig. 3148.

Horizontal Saw Frame.—This machine is designed for the more expensive woods, such as mahogany, and is finding much favor because it will cut at a very high speed, the saw travelling about 150 feet per minute.

The roughest shaped trunk may be easily fixed on the travelling table, and a thin saw may be used as it may be very tightly strained. This machine is used either for breaking down timber, or for converting it from the log to any desired thickness, the thickness of the boards being very readily and easily varied.

The machine consists essentially of a framework carrying either one or two very thin and tightly strained saws operating horizontally and cutting on both strokes, so that the feed is continuous, the construction being as follows:

VOL. II.HORIZONTAL SAW FRAME.PLATE XXV.
[Large
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Fig. 3149.

Referring to [Figs. 3149] and [3150], a is a base plate or bed carrying two uprights or standards b, b, having guideways c, c, for the cross-head d, which has slideways e, e′, for carrying the frame f, f, which carries the saw g, which is guided on each side of the work by the guides h, h′.

Fig. 3150.

The frame f, f is connected to the slides j, j′, and has the rod k, to which the connecting rod pin l is attached, and the rod m, which acts as a stretcher. A connecting rod p, connects the pin l to the crank pin q, on the crank q′, which is driven by belt from the pulley t, a fly-wheel being provided at s.

It is obvious that as the crank revolves the saw reciprocates, its line of motion being determined by the guideways e, e′.

Fig. 3151.

The construction of the saw is shown in [Fig. 3151], and it is seen that for half its length, the teeth are formed to cut when the saw moves in one direction, while for the other half the teeth slope in the opposite direction, and are therefore arranged to cut when the saw is on the opposite or return stroke, and the construction whereby the saw is enabled to cut on both strokes is obtained as follows:

Referring to [Fig. 3149], the two slides e, e′, on which the saw-carrying frame f f slides, are not in line or parallel one with the other, but each slide is at an angle of about 85 degrees to the line of feed, so that as frame f is reciprocated at each stroke, one end of the saw advances towards the cut, and the other recedes from it, thus causing the saw to cut first on one half and then on the other of its length, one half cutting on the forward, and the other on the return stroke.

The studs or saw-buckles for attaching the saw to the frame are shown in [Fig. 3151], in place on the ends of the saw, the part i, that fits in the frame f, [Fig. 3149], being squared so that the saw cannot be twisted in tightening up the nuts of the saw-buckle.

The belt works for driving the saw are arranged as follows: at t are the fast and loose pulleys for driving pulley r, the belt passing from t over two pulleys (shown dotted in, [Fig. 3149]), u, u′, whence it stretches to the crank driving pulley r, whose bearing is provided on the cross-head, so that the two move together when the cross-head is altered in height from the work-table or carriage, to accommodate different thicknesses or diameters of logs.

It is obvious that in proportion as the cross-head is set nearer to the carriage, the belt from t to u, u′ would become slack; provision is made however, to prevent this as follows:

Pulley u, is carried on a frame or swing lever x, to which is attached by rope v the weight w, which therefore regulates the tension of the belt.

The cross-head d may be raised or lowered by belt power or by hand, as occasion may require, the usual course being to move it to nearly the required position by belt power, and then complete the adjustment by hand, a graduated scale being provided as shown, whereby the rack can be set to cut the required thickness of plank without measuring the timber.

The belt motion for raising or lowering the cross-head is obtained by the pulleys at y, the wheel for the hand adjustment being shown at y′. In either case the bevel gear wheels z, z′ operate, respectively, a vertical screw engaging a nut on the cross-head.

The log feed is obtained by a motion separate from the return motion, there being three rates of feed and a quick return motion, the construction being as follows:

Referring to [Figs. 3149] and [3150], a is a belt pulley fast on the crank shaft, and driving pulley b, which is also shown dotted in. Pulley b drives the vertical shaft c, on which is the cone pulley d, having three steps, and which drives (by means of belt d′) cone pulley e, on which is a worm f, driving the worm wheel g, which runs idle on its shaft unless engaged therewith by means of the clutch h. The shaft of worm wheel g is omitted in [Fig. 3149], so as to leave the belt-shifting mechanism for pulleys q, q′ exposed to view. On this shaft however is a pinion driving the gear wheel k, on whose shaft is a pinion l, driving the gear m, which engages the rack n, on the under side of the carriage.

The clutch h is engaged by the lever i, to the upper arm of which is attached the rod j, j, from the lever p, hence operating p (which is done by hand), back and forth, throws clutch h into and out of gear with the worm wheel g, and puts the carriage feed on or throws it out, according to the direction in which p is moved.

The upper end of shaft c is carried in a bearing on the cross-head, and is provided with a featherway or spline, so that as the cross-head is raised or lowered the upper end of c passes through its upper bearing, and the pulley b travels with the cross-head. The three rates of carriage feed are obviously obtained by means of the three steps on the cone pulleys d and e.

We have now to explain the construction of the mechanism for traversing the table back, and giving it a quick return motion, or in other words a quicker motion on the back than on the feed traverse, and this is arranged as follows:

q, is a fast and q′, q′′, are loose pulleys, one driven by an open belt r, [Fig. 3150], and the other by a crossed belt r′, from a countershaft. The belt-shifting forks are operated by lever s, whose upper end engages with the rod t, which is operated by the lever u.

The loose pulleys q′ and q′′ are twice as wide as the fast pulley q.

Now suppose that lever u is moved to the right, and the belt would be moved from the loose pulley q′′ to the fast pulley q, while the other belt would merely be moved or shifted from one to the other side of loose pulley q′.

Similarly if lever u, be moved to the left, the belt on the loose pulley q′ will be moved on to the fast pulley q, and the belt on pulley q′′ would simply be moved across the face of the pulley, and as the countershaft pulleys for the two pulleys are of different diameters, therefore two rates of motion are obtained.

The shaft v, on which pulley q is fast, drives the pinion l, which drives m, the latter gearing with the rack beneath the carriage.

The carriage is guided by the wheels z, which are secured to it, and run on the iron guideways z′, the flanges of the wheels preventing side play, and causing the carriage traverse to be in a straight line.

WOOD-PLANING MACHINES.

The simplest form of planing machine for wood work, is the hand planer or buzz planer, as it is termed, an example of this class of machine being shown in [Fig. 3152], which has been designed and constructed by George Richards, for the use of pattern-makers.

Fig. 3152.

It consists of a frame carrying a revolving shaft, which is by some called the cutter head, and by others the cutter bar, and to which the cutters or knives are attached.

The work is rested upon the work table, or else pressed against a guide or fence, and fed by hand over the revolving knives, whose cutting edges protrude above the surface of the table, to the amount of the depth of cut it is intended to take.

Fig. 3153.

In this example, however, the table is made in two sections, the front one of which is below the cutter edges to an amount equal to the depth of the cut, and the back one level with the cutter edge, when the latter is at its highest point in its path of revolution, the construction being shown in [Fig. 3153], in which j, j, represents the top part of the main frame of the machine, c the cutter head, b the front or feed table, a the back or delivery table, and w a piece of work being fed in the direction of the arrow.

Upon the upper surface of the frame j, j, and on the feed side of the cutter head is the carriage g, to which are pivoted two links l, l, which support the feed table b. At d is a hand wheel whose screw has journal bearing in a lug from the table, while the screw threads into a nut provided in the carriage. Obviously then by operating the hand wheel d, carriage g is moved along the top of the frame j, and the height of table b is adjusted. Thus if the carriage g is traversed to the left, the link l would fall more nearly to a horizontal position, and table b would lower. Or if g were moved to the right, links l would stand more nearly vertical, and table b would be raised, it being understood that table b is not permitted to move endways. Similarly by means of hand wheel c, carriage h may be moved to adjust the height of table a.

By this construction, the work can bed fairly on the delivery side, as well as on the feeding side of the cutter head, which is not the case when a single table is used.

It is obvious that the work must be fed in opposition to the pressure of the cut, which endeavors to push the work back from the cutter, and this limits the size of work that the machine can operate upon.

Fig. 3154.

The work can be fed easier however, with a cutter skewed or set out of line with the axis of the cutter head. Thus in [Fig. 3154], is the common form of cutter head, carrying two knives placed diametrally opposite, so that the weight of one counterbalances that of the other, and the head will therefore run steadily and smoothly. The knives k, k′ are here set parallel with the axis of the cutter head, hence the whole length of the cutting edge meets the work at the same instant, and a certain amount of time must pass after one cutting edge has left the work before the other cutter edge meets it.

Fig. 3155.

This is remedied by the construction of cutter head shown in [Fig. 3155], in which three cutters are used, and each cutter is set askew, or out of parallel with the axis of cutter head, so that the knife begins to cut at one end, and the cutting action gradually extends to the other, hence the cutting action is more continuous and uniform, and better work is produced, while less power is required to drive and feed the machine.

Fig. 3156.

[Fig. 3156] shows a cutter head with two skew cutters.

The cutter head is provided with a cover or guard, which is arranged as follows: In the table is cut a groove or slideway, in which a slide fits, and to this is attached a thin sheet-iron guard. To the slide is attached a weight, which draws the guard back to the fence after the work has passed over the cutter head. By this means the guard covers all the knife edge that protrudes beyond the work, no matter what the width or thickness of the work may be; the guard can however be fixed in position when a number of pieces of the same size are to be planed.

The fence provides a guide surface for the work, and its face may be set at any required angle to the surface of the work table. Suppose, for example, that the sides or edges of a piece of work require to be at an angle of 100 degrees to the top and bottom surfaces, then the top surface may be planed first, and the fence being set at an angle of too degrees to the table surface, the top of the work may be pressed to the surface of the fence while fed across the cutter, and as a result, the side or edge will be planed at 100 degrees to the top.

ROLL FEED WOOD PLANING MACHINE.

[Fig. 3157] represents a roll feed wood planing machine, designed and constructed by George Richards & Co., of Broadheath, near Manchester, England, the construction being more fully shown in the detailed figures following. The machine consists essentially of a framework, carrying a cutter head with two knives, and having a pair of feed rolls, in front and a pair behind it. The front pair feed the timber to the cutter head and the back pair deliver it from the cutter head.

Fig. 3157.

Each pair of rolls is geared together, so that both the top and bottom rolls act to give a positive feed. Immediately in front of the cutter head and between it and the feed rolls (i. e. the front pair of rolls), is a pressure bar extending across the full width of the machine, and having at its lower extremity a steel spring which presses the work down to the table, and thus causes it to be planed of an equal thickness throughout its length. Immediately behind the cutter head and between it and the delivery rolls (i. e. the back pair of rolls), is a pressure bar that also extends across the machine and prevents the timber from rising up from the table after it has passed the cutters, all timber being found to have a tendency to rise after having been acted upon by the cutters. The arrangement of the feed rolls, delivery rolls and pressure bars is shown in [Fig. 3158], in which t, t, t, represents three sections of the work table and w, w, a piece of work passing through the machine in the direction of the arrow. Feed roller f is fluted to increase its grip upon the work and insure a positive feed. The lower feed roller f′, and the lower delivery roller d′, are fixed in position, their upper surface projecting above the work table to about 1⁄100 inch. This is necessary to take the thrust of the upper rolls (f, d) and prevent them from forcing the work down upon the surface of the table with an undue amount of pressure, which would induce friction and consume an unnecessary amount of power in driving the rolls. The method of adjusting the lower rolls will be explained presently.

Figs. 3158, 3159.

Between the cutter head c and the feed roll f is the pressure bar p, and behind the cutter head is the pressure bar b, both these bars being more clearly seen in [Fig. 3159], in which the work w is shown entering the machine, and the lower rolls and work table are removed.

Fig. 3160.

Pressure bar p has at its lower end a steel spring j, [Fig. 3159], and is supported at each end by circular links y, projecting into grooves provided in the main frame of the machine, as shown in [Figs. 3160] and [3161], in which c is the cutter spindle, y the circular link at the end of pressure bar p, and y the circular link at the end of pressure bar b, the two fitting into the one stepped groove.

Fig. 3161.

This groove is concentric with the cutter spindle c, so that the pressure bars keep at a positive or equal distance from the edges of the cutter, no matter what the thickness of the work or the depth of the cut may be.

Fig. 3162.

In [Fig. 3162], the work is shown passing beneath the two upper rollers, and the spring j (which extends the whole length of the pressure bar), is depressed from the weight of the bar. By this construction, the work is pressed to the table at a point as close as possible to the cutters. The pressure bar p cannot drop beyond a certain point, because of its tail piece y′, [Fig. 3160], which rests on the top of the frame at y′′ when the bar p has fallen to its required limit.

The feed pressure bar p is bolted to its circular links, as shown in [Fig. 3162], in which y is a part of the circular link which is bolted to the pressure bar p.

The delivery pressure bar b ([Fig. 3160]) is riveted to and forms part of its links y. It acts through the medium of spiral springs s, which are carried in cases or boxes s′, which overhang the end of the bar b. A set screw s′′ regulates the pressure of the spring, and a screw a ([Fig. 3162]) regulates the height of the pressure bar.

The adjustments of the feed and delivery rollers are made as follows:

The feed pressure is obtained through the medium of weights, shown at w, w′, in [Fig. 3163], upon the bars a, a′, whose ends are pivoted to the lower ends of links m, n, the upper ends of which are pivoted to the side frame of the machine.

Fig. 3163.

Bar a engages or rests at e, on a lug or projection on the link i, which fits in a recess provided in the side of the frame. This link i, extends up and has a bearing to receive the feed roller (f, [Fig. 3160]), whose driving gear is shown at o.

It is obvious therefore, that the amount of pressure on the feed roller f may be varied by moving the weight w along the bar a.

Similarly for the delivery pressure roller, the weight w′ is adjustable along the bar a′, which is pivoted to link n, and rests upon i at e′. The link i′ is guided in ways in the side frame of the machine, and at its upper end carries the delivery roller d, whose driving gear is shown at o′ ([Fig. 3163]).

It is obvious that there are bars a, a′, and links i, i′, on both sides of the machine, so as to adjust the feed rollers at both ends.

The work table and the two lower rollers are adjusted for different thicknesses of work as follows:

Fig. 3164.

Between the two main side frames m and m′, [Fig. 3164], are two frames having corresponding inclines or slideways, of which the upper carries the work table and the lower rolls.

The lower incline sits on ways k, k, [Fig. 3164], cast on the side frame, and is capable of being moved endwise by means of the hand wheel r, [Figs. 3163] and [3164], which operates a screw threaded into the lower incline. When the lower incline is moved endways, the upper one, which carries the work table, is moved vertically, and as the lower feed rolls are carried by the upper incline, and the upper rolls are guided to move vertically only, the lower rolls maintain their position beneath the upper ones, or in other words, the table and lower rolls move together in a vertical direction only, when the lower incline is operated.

The lower rollers run in bearings formed in the links q, q, [Fig. 3160], which are pivoted at their other ends to the upper incline. On the sides of the incline are lugs through which pass adjustment screws z, which by operating beneath the outer ends of the links q, q, adjust the heights, bearings of the lower rollers so that the uppermost point on the circumference stands about 1⁄100 inch above the level of the work table surface.

The upper surface of the lower incline is shown by the dotted line f, f, f, in [Fig. 3163].

We may now consider the means employed to drive the rolls, first remarking that the upper rolls f and d, are given a motion slightly quicker than the lower ones, so as to cause them to clean themselves (from particles of wood that might otherwise cling to them), by a sort of rubbing action which is due to their velocity being greater than the lower rolls and the work. This rubbing action is due to the fact that the work has the slower motion of the lower rollers, resisting the quicker motion of the upper ones, and as a result there is a certain amount of slip between the upper rollers and the work.

Another and important feature, is that the upper delivery roller (d, [Fig. 3160]), is placed from 1⁄4 to 1⁄2 inch nearer to the cutter head than the bottom delivery roll, which assists in keeping the work down upon the table.

Fig. 3165.

The mechanism for driving the feed rolls is shown in [Figs. 3163], [3164] and [3165], in which l, l are the pulleys which receive motion from a countershaft, and drive the cutter head, being fast upon its shaft, as is also the pulley s, which connects by belt and drives pulley t, on whose shaft is the stepped pulley u, which connects by a crossed belt to pulley v, which drives the feed gear through the medium of the pinion a. The two steps on pulleys u and v, obviously give two rates of feed.

The pinions o and o′, both receive motion from the gear wheel e, this part of the gearing consisting of gears a, b, c, d and e, and as both pinions receive motion from the same gear, their revolutions are equal. The lower feed roll is driven by the pinion p, which gears with and is driven by wheel d, whose face is broad enough to meet p, which sits nearer to the frame than pinion o does, so that the teeth of p may escape those of o.

Now the velocities of all the wheels o, o′, e, d and p, will be equal at the pitch circles, because they constitute a simple train of gearing. Thus if d moves through a part of a revolution equal to the pitch e, then o and o′ will move through the same distance, because the wheels are in continuous gear. Now as d drives p, therefore the velocity of p must at the pitch circle be the same as d, let the numbers of teeth in the respective wheels be what it may, and it follows that the velocities of o, e, d and p are at the pitch circles equal. But by making the diameter of the upper roll greater than the pitch circle of its gear o, and the diameter of the lower roll correspondingly less than the diameter of the pitch circle of its pinion p, the velocity of the circumference of the upper roll will be greater than that of the lower roll, and the rubbing action before referred to with reference to the upper roll will thus be induced.

Referring now to the lower delivery roll, its pinion x receives motion through gear w, which is also driven by gear e, which has a broad face so as to gear with x, which is behind and below gear o′. In this case the circumstances are the same, as will be seen from the following.

An inch of motion of the pitch circle of e will produce an inch of motion at the pitch circles of o′ and of w and x, hence the velocities of the pitch circles will be equal, and if the diameters of the upper and lower rolls are equal, or the same as the pitch circles, the velocities of the circumferences of the respective rolls will be equal, but by making the diameter of the upper delivery roll greater than that of the pitch circle of its pinion, and that of the lower roll less, a rubbing action is induced between the roll and the work, and this rubbing action will keep the roll clear of any dust, etc., that might otherwise cling to it.

Fig. 3166.

The cutter head is formed triangular, as in [Fig. 3166], carrying three knives. The knives are set at an angle to the axis of the cutter bar or cutter head. When the knives are at an angle, they take their cut gradually, and the cutting action is more continuous, which diminishes the vibration of the machine, and causes the finished surface to be smoother. Furthermore, the knives take a shearing cut, and therefore cut more easily and freely.

In some practice the knives are made spiral, but spiral knives are difficult to bed properly to the cutter head, and also difficult to grind. The cutter head is made of a solid mild centre steel forging, and runs in phosphor bronze journals, in which it has about 1⁄8 inch end play, which tends to distribute the oil along the bearing. It is driven by a pulley at each end, the pulleys seating on a cone.

The amount of skew is about 3⁄4 inch for a cutter head carrying a knife 30 inches long, and about 3⁄8 inch for a cutter head whose knives are 10 or 12 inches long.

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Fig. 3167.

[Figs. 3167] and [3168] represent a machine in which there are three feed rolls and one delivery roll, all being driven.

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Fig. 3168.

First there is the pair of feed rolls the bottom roll of which is set sufficiently above the surface of the table to relieve the work of friction upon the table.

The work next meets an upper feed roll that acts to force the work down to the table surface (there being in this case no lower feed roll).

After passing the knives, the work is carried out by a delivery roll that also acts to keep the work down to the table face.

All three upper rolls are provided with rubber springs in the casings h, h′.

p, p, are the pulleys for the cutter head and b, those for the feed works, which have two speeds. The feed is thrown in and out by the lever d, which moves the pinion d endways and engages or disengages it from its gear wheel.

Fig. 3169.

[Figs. 3169], [3170], [3171] and [3172] represent a pony planer, by P. Pryibil.

Fig. 3170.

Referring to the sectional view [Fig. 3170], the work table slides in vertical slideways s, in the side frames, the elevating screw being operated by the bevel gears at g, which receive motion from the hand wheel m in [Figs. 3170] and [3171]. There are four upper rolls, marked 1, 2, 3 and 4 respectively, and of these the first two are fluted in the usual way. There are two lower rolls, marked respectively 5 and 6. The fluted feed rolls 1 and 2 are weighted, the weight lever acting on the rod r, which at its upper end connects to the cap y, which covers the bearings of feed rolls 1 and 2. By this construction the two rolls are acted upon by the same weights and levers, the rolls being of course weighted at each end, or in other words on both sides of the machine.

Fig. 3171.

The delivery rolls 3 and 4 receive their pressure by the construction shown in [Fig. 3172], the bearings of the rolls being held down by rubber cushions receiving pressure from the cap e, screwed down by the bolt and nut.

Fig. 3172.

The rolls 5 and 6 are idle rolls, and are set to just relieve the work from undue pressure on the work table.

By this construction of feed mechanism the following ends are attained. First, sufficient feed power for heavy cuts is obtained without driving the lower rolls. Second the work is held to the table on both sides of the cutter head, hence there will not be left on the end of the work the step that is left when but two upper and two lower rolls are used, and which occurs because the work falls after leaving the feed rolls, whereas, in this machine the work is held to the table by rolls 2 and 3.

The cutter head h, [Fig. 3170], has in front of it the pressure bar p, whose lever is shown at l and the weight at w. On the delivery side of the cutter head is a pressure bar r, which is acted upon by a spiral spring in the box c. In the engraving to the right of [Fig. 3170] the knife k is shown in action on a piece of work, and it is seen that the end of the pressure bar p coming close to the edge of the knife prevents the pressure of the cut from splitting or splintering off the end of the work at a, and therefore acts as what is termed a chip break. Furthermore, the sides of the cutter head between the knives being hollowed out gives the shavings s room to curl in and prevent the work from splintering at the end when the cut is terminating.

Balancing Cutter Heads and Knives.—Planer knives must be balanced as accurately as possible, in order that they may run steadily and smoothly, and therefore produce smooth work.

The first requisite for proper balancing is that the cutter head itself be properly balanced, and in order that this may be the case the faces forming the knife seats must be equidistant from the axis of the cutter head, and the journals must run true, being best tested on dead centres. The holes for the cutter bolts should all be drilled to the same depth, and tapped equally deep. The faces or seats for the knives should be parallel one to the other, and this may be tested by a pair of straight edges, one pressed to each face and the width between them measured at each end, or if a long surface plate is at hand, one face of the head may be rested on the surface plate, and the straight edge ruled on the other face, and its distance measured from the surface plate at each end, with a pair of inside callipers delicately adjusted.

A straight edge rested lengthways along the knife seat of the head and projecting over the journal will show whether each knife seat is equidistant from the journal as it should be, the measurement being taken with a pair of inside callipers adjusted to just sensibly touch the journal and the straight edge. This measurement should be taken at each end of the head.

In all tests made with straight edges, the straight edge should be turned end for end and each measurement repeated, because, if the straight edge is true, turning it end for end will make no difference to the measurement, while if the straight edge is not true the measurement will vary when the straight edge is reversed.

If the cutter head is square, the straight edge tests may be applied to all four of its faces, and they may then be tested with a square, and if the head shows no error under these tests, and the bolt holes or slots are of equal diameter and depths, the head will be correct as far as it can be tested without running it.

A cutter head may be roughly tested by placing it between the lathe centres, both centres being oiled and delicately adjusted so as to just prevent end motion of the head without perceptible friction when the head is revolved by hand.

The first thing to test is whether the journals run true, which may be tested by a pointer fastened in the slide seat, and moved up to just touch the journal. The pointer should be soft, and not a cutting tool, unless indeed it be set so high in the slide rest that it cannot cut.

If the journals do not run true, the next thing to test is whether the body of the head runs true to the centres, which may be done by first setting a pointer to just touch the extreme corners of the head at each end and in the middle of its length, and if there is an error in the same direction as the test at the journal shows, then the centres of the head are out of true, and must be corrected before a test of this kind can be proceeded with.

But the body of the head may show true at the corners while the journals do not run true, and if this is the case we may further test the body of the head as follows:

With the lathe slide rest at one end of the head we may set a pointer so that it will just pass on the flat of the cutter seat and make a mark when the slide rest is traversed along the lathe bed. We then move the slide rest so as to bring the pointer to the journal end of the head; give the head a half a revolution on the centres and try the pointer on the flat of the cutter seat, and if it makes a mark of equal strength, then two faces of the head are equidistant from the axis of the head.

The next thing to do is to make the same test at the other end of the head, and in order to do this without moving the pointer, and therefore without altering its adjustment, we must move the slide rest so as to bring the pointer opposite to the lathe centre, and out of the way of the body of the head, and take the cutter head out of the lathe and turn it end for end, and then repeat the test with the pointer, which will show whether both ends of those two flats are alike.

This test we repeat on the other two faces of the head, and if they show true, then the head is true, except the journal, which must be made true with the head.

This testing will clearly show any want of truth in either the head or the journals, and in what direction correction needs to be made.

Now suppose the above tests do not disclose any error, either in the journals or in the head, and we may continue the tests by revolving the head by hand between the dead centres, and apply the pointer to the journals while the head is revolved as quickly as possible; as, however, the head cannot be revolved very fast in this way, we may adjust the lathe centres as before described, and revolve the head as rapidly as possible by hand, and letting it come to rest mark which side is at the bottom, and if on several tests the same side comes to the bottom of the plane of revolution at each test, that side is the heaviest and must be corrected. If it is found to be a flat side or cutter seat that comes to rest at the bottom, the correction can be made by deepening the bolt holes on that side, measuring to see which bolt hole is the shallowest, and making all as nearly as possible equally deep.

If the head has T slots instead of bolt holes, the slots may be cut or filed out to effect the balance, care being taken to make the slot equal in distance from the edges of the cutter seat face.

The next essential in order to have a properly balanced cutter head is that the bolts and nuts all weigh alike, and that the bolts be of the same length. The bolts should be turned to an equal diameter of equal length and threaded for an equal distance along the body of the bolt, and the nuts should be of equal depth and all fit accurately to the same wrench, and the weight of the bolts and nuts when put together may then be equalized by reducing the heads of the heavy ones.

We now come to the balancing of the knives, which must be made of equal thickness and width throughout, with the slots for the bolts of equal widths and depths.

The knives require to be as accurately balanced as it is possible to make them, for otherwise they will cause the head to jar and vibrate violently, thus producing rough work. The knives weighed individually may be of the same weight, and yet the head may run out of balance by reason of one end of a knife being heavier than the other end.

Fig. 3173.

[Fig. 3173] represents a machine constructed by J. A. Graham & Co., for balancing planer knives, moulding knives, cap screws, and knives in rotary cutter heads of all kinds.

Let it be supposed that the knives are the same specific weight, but that there is an excess of weight at one end; when revolving on the head, a violent jarring or throwing will be caused by reason of the excess. The knives could be reduced to the same specific weight by the aid of common grocers’ scales, but the ends could not be made the same proportional weight as on such balance.

In the cut s s is the base of the scale; l, m the standards for the support of the scale beams b b and k k.

d, d′ are two pivots of the scale beams.

d is the loop on which the pivot d works.

e is a joint in the loop.

d′, e′, and f show the loop and connection.

c is the sliding table which has the stop c′, and is adjustable for different lengths of knives.

a a is a knife in position for balancing endwise.

g is a slotted piece, and is held to the scale beam by the screw v. The slot in g is shown at g′, and limits the travel of the scale beams.

h is an angular piece fastened to the lower scale beam, and receives the screw j.

i is a small weight used for fine adjustment.

o, o are weights which slide along the scale beam k k, and are held in place by the thumb screws p, p.

n shows side view of weight, which is so constructed as to allow it to be easily removed. In using the machine the lightest cutter or knife of the set is first found and its two ends balanced, by turning it end for end on the scales, and reducing the weight of the heavier end. The other knife or knives are then balanced without disturbing the adjustment of the machine as made for the first knife.

ENDLESS BED OR “FARRAR” WOOD SURFACING MACHINE.

This class of machine has a bed composed of slats which are connected together and driven by a chain.

Fig. 3174.

[Fig. 3174] represents an endless bed double surfacer constructed by the Egan Company. The upper cylinder may be raised or lowered to suit the thickness of the work. The front feed roll is in two sections, enabling two boards of unequal thickness to be planed simultaneously to an equal thickness. These rolls are held to the work by a leaf spring, as shown in the cut, the tension on the spring being adjusted by the screw at d, d serving as a check-nut.

Fig. 3175.

A longitudinal section through the centre of the machine is shown in [Fig. 3175]. The spring s bears at each end on a block t, which carries the bearings for the feed roll. Feed roll m is held down by the screws e, e, acting on a rubber cushion or spring, and is provided with a scraper to clean it from dirt, etc.

The travelling bed is composed of slats s connected together by the chain shown, and resting upon slides a, a, supported by the girts b, b.

The chain is operated by the spur or sprocket wheel w, and is therefore pulled and not pushed, which tends to keep it under tension, and therefore rigid upon the top side.

The ends of the slide a, a are depressed so that the slats shall not tilt up at one corner above the level of the slide when in the positions denoted by s′.

The lower cutter head is carried in a sliding head or frame j, adjusted for height by the gears at h, which operate screw h, while the bed above it is adjusted by the gears at f. It is obvious that the bottom surface of this bed is set at the same height as the lowest point in the path of revolution of the cutting edges of the knives of the front cutter head or cylinder. The upper delivery roll n is provided with a scraper.

PLANING AND MATCHING MACHINE.

Planing and matching machines that are made narrow to suit the planing and matching of boards for flooring are sometimes called flooring machines, the distinctive feature of a flooring machine being that it is (unless in the case of a double machine) made narrow (because flooring boards are narrow), and this makes the machine very stiff and capable therefore of a high rate of feed and speed.

Fig. 3176.

[Fig. 3176] is a general view, and [3177] a longitudinal section through a standard planing and matching machine of recent design, constructed by Messrs. J. S. Graham & Company. The plank passes through two pairs of rollers before meeting the front cutter head. The side heads then come into operation cutting (in the case of flooring) the tongue on one side of the plank and the groove on the other, the under side of the plank being dressed last.

The machine is built in three widths viz., 8′′, 14′′ and 26′′, each planing to 6′′ thick and matching as wide as it planes.

In place of matching heads, heads for beading, rabbeting, or fancy siding may then be used.

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Fig. 3177.

The board r ([Fig. 3177]) is fed in over the grate m′ until it reaches the rolls e and f′, which are held in place by the boxes fitted to the roll stand n′, and brought to bear on the lumber by means of the screw a′, equalizing bar m and nuts p, p, together with the lever y y and the weight x.

Fig. 3178.

After the lumber leaves the second pair of rolls, it runs over the bed plate w ([Fig. 3178]) and under the shoe l, the duty of which is to hold the board firmly against the bed plate, and also to break the chips on a heavy cut. After leaving the shoe it is operated on by the upper cutter head h, then it passes beneath the pressure bar g, which holds the lumber firmly while it is acted on by the matcher c.

Fig. 3179.

It then passes beneath the cleaner e′′ ([Fig. 3177]) and under the delivering roll, which is held down by the weight u in connection with the lever v and screw a′, the top which is shown at c ([Fig. 3179]). The board then passes underneath the pressure bar q ([Figs. 3177], [3180]) and over the under cutter s, from which it passes finished.

Fig. 3180.

The pressure bar q is moved up and down by turning the shaft a′′, the motion of which is given to the screw h′ by means of a pair of bevel gears. k′ is also a scraper that cleans the board before it passes under the pressure bar q. The under cutter is adjusted for depth of cut by turning hand wheel a′, which moves the screw u′. The rolls are raised and lowered by turning the shaft at p ([Fig. 3176]).

In feeding two boards through the machine, one thicker than the other, that end of the roll that passes over the thick board can raise up without taking the pressure off the thin one at the other end of the roll. This raising mechanism is shown in [Fig. 3179]. The bevel gear c works over a ball joint q′. The shoulder b′ on the screw a′ works on the under side of the ball q′. The shaft a passes through the tubular shell b to the opposite end of the roll. The cross tie j is bolted to the roll box k′′.

c, [Fig. 3178], shows matcher hanger in position. It is gibbed to the bed plate z by the gib f, which is so constructed as to be free from dirt. The sliding gib f is adjustable for wear. One matcher hanger is moved by the screw e, the other by e′. The left hand matcher hanger is moved by the shaft l′ ([Fig. 3177]), which passes along the side of the machine until it reaches the shaft e, where its motion is imparted to the screw by means of a pair of spiral gears. An index at the rear of the machine enables the operator to set the matcher heads to any desired width. The right hand matcher hanger, together with the guide, can be moved across the machine by turning the screw e′ at the side of the machine ([Fig. 3176]).

The upright d which carries the pulley which drives the top cutter head, or cylinder as it is sometimes termed, is set at an angle so that the cylinder belt will always be of the same tension.

The top cylinder is raised by the shaft d ([Fig. 3176]) and screw b. It is held in place by the nut m ([Fig. 3177]). The bar i ties the cylinder boxes together. k is held down by the weight i, and yields with the pressure bar l.

The spindle of the matcher c′ ([Fig. 3177]) is driven by a belt which comes from the pulley h and passes over the guide pulley k, and then to the pulley b′.

The lower end of the matcher is held in place by being gibbed to the cross tie p′, [Fig. 3177], which is adjusted and kept in position by the screw o′.

s′ sustains the matcher spindle by means of an adjustable step.

y′, [Fig. 3176], is the feed shaft which drives the gearing that operates the rolls. The pulley that drives the feed shaft is shown at l′ ([Fig. 3176]). The belt passes over this pulley and under and over the tightener pulleys w′, w′, then to the pulley u′ which is on the feed shaft y′.

The apron m′ in front of the under cutter s ([Fig. 3180]) is easily dropped to m′′ by loosening the nut r′ and releasing the bolt t′ so as to allow the apron m′ to drop.

This enables the operator to have free access to the under cutter for sharpening knives, etc. z′ is the bed plate over which the lumber passes before it reaches the under cutter.

Fig. 3181.

A planing and matching machine designed and constructed by Messrs. London, Berry and Orton is represented in [Fig. 3181]. In this machine the upper surface of the board is surfaced first, and the matching second, the under surface being operated upon the last. The method of suspending the upper feed rolls of this machine is shown in [Fig. 3182], in which a is an upper and b a lower feed roll. The upper roll a is suspended by the link c, which is supported by the link d, and also by link e, these three links forming a parallel motion which guides a in a vertical line.

Fig. 3182.

At f (which is fast to e) is a bearing for the screw g, and the pair of bevel gears g that drives it. This screw threads into the nut h on the rod i, which receives the pressure of the bar j and weight k.

The lower feed rolls being larger in diameter gives them increased grip on the work, and gives it a better base, and also makes it enter and leave the rolls easier.

Each matcher bracket is fitted with a screw by which it can be moved at will across the machine, and by turning one other screw with the same wrench that moves the others, both brackets are firmly set to the slide and all screws held firmly. There are three changes of feed. The top cutter head is provided with improved pressure bars, which are set to or from the head by means of a double eccentric, which, while they can be set at any desired distance from the knives, limits their movement when moved towards them, rendering it impossible to get them into the cutters.

TIMBER PLANER.

The term timber planer implies that plain knives only are used in the machine, which is therefore intended for producing plane surfaces. It also implies that the machine is designed for heavy or large work, such as is found in ship yards, bridge construction or car works, etc., etc.

In such work the cuts taken by the machine are sometimes very heavy, and as a result the feed works of the machine require to be very powerful and positive.

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Fig. 3183.

[Fig. 3183] represents a timber planer designed and constructed by J. S. Graham & Co., to plane all four sides of the timber at one passage through the machine.

The timber passes through three pairs of feed rolls before reaching the first cutter head, which planes the bottom surface.

It then passes to the side heads, which dress both sides simultaneously, and then passes beneath the cutter head that finishes the upper surface, and is finally delivered from the machine by a pair of delivery rolls.

The work is passed over roller b, the fence or gauge being shown at b′. 1 and 2 are the first pair of feed rollers, a and b being merely adjustable intermediate wheels, which by means of the pieces c′, b′, may be set so as to connect rollers 1 and 2 together, whatever their distance apart may be, or in other words whatever the thickness of the work may be.

From 1 and 2 the work passes to the second pair of feed rolls 3 and 4, c and d being the intermediates.

Similarly 5, 6, 7 and 8 are feed rolls, and e, f, g, h intermediates. The first head is shown at k′, the side heads at h, and the last head at i′, the latter being carried on a sliding head j, which is secured in its adjusted position by nuts i. On the side of the frame d on which j slides is a graduated index to denote the adjustment of the head i′.

Fig. 3184.

The construction of the parts in immediate connection with the front cutter head is shown in [Fig. 3184]. n is the frame corresponding to n in [Fig. 3183], the rolls 5 and 6 also corresponding in the two figures.

Upon n is a slide s having an arm g, carrying the roll g′, which holds the timber down to the cut of the cutter head k′. The pressure of roll g′ to the work is given through the medium of the rod a′, which receives the pressure of the equalizing bar x, [Fig. 3183].

Fig. 3185.

The bottom surface of the timber passes over the bed plate u, [Fig. 3185], which raises and lowers with the lower feed rolls, being connected by the screw i, [Fig. 3184], to the bearing box of feed roll 6.

All the lower feed rolls are operated simultaneously by means of the rod l, having for each lower feed roll a worm, driving a worm wheel l′ on a screw threaded into a hub m in each feed roll bearing; the crank for operating l is seen at p, [Fig. 3183].

The passage of the timber through the machine is continued in [Fig. 3185], in which it is seen that after the lower surface of the timber has been planed it passes from the cutter head k′ to a bed plate v and is thus supported by a flat and true surface while the side cutter heads plane the two sides, one of these side heads being shown at h. The side heads are carried in hangers, one of which is shown at p′. It is gibbed to the under cutter frame u′ by the sliding gib x, the left hand head h being moved across the frame by the screw f′. The hanger is held at the bottom by the gib t and the cross tie t′. p is the pulley for the side head h, the end wear of whose shaft is taken up by the adjusting screw s′, r′ being a leather washer, and r the end of the shaft.

Fig. 3186.

The top box h′ moves across the machine in the slideway b′′, [Fig. 3186], a′′ being a part of the box h′.

Upon leaving the side heads the timber will have been planed on three sides and the side surfaces dressed to a right angle with the bottom surface.

It is then guided to the upper cylinder as follows:

The friction rolls k, k are to relieve the bed a′′ from the pressure due to the feed roll z′ and the roll j′, which holds the timber after it has left the cutter i′, and thus prevents it from vibrating. After leaving the pressure roll j′, the timber passes under the scraper d′, [Fig. 3183], and thence to the delivery roll 7, which is held down by the weight l, in connection with the lever l′.

By means of this construction all the cutter heads act upon the timber within the short distance of 221⁄2 inches, while the side heads act within 81⁄2 inches of the under cutter. This is desirable, being conducive to the production of true work, which it is more difficult to produce in proportion as the cutter heads are wider apart. This machine will joint as narrow as 2 inches, and plane as thin as 3⁄4 inch.

The upper cylinder i′, [Fig. 3183], is adjusted for height or thickness of cut by means of the screw f, and is locked in its adjusted position on d by the nut i.

The feed is started or stopped by operating the hand wheel o′.

The upper rolls are raised or lowered simultaneously by power, by means of the shaft s, and the bevel gears r, which operate the screw a′.

The upper cylinder is driven by belt from the pulley q, the under cylinder from q′ (both these cylinders being driven from both ends). p′ is the driving pulley for the feed belt, which passes to n′, which, through k′′ and y′, drives y, which drives the feed rolls.

The machine will feed from 25 to 60 feet per minute.

PANEL PLANING AND TRYING-UP MACHINE.

This class of machine is employed for the production of true surfaces, and is now used upon much of the work that was formerly assigned to the Daniels class of planing machine. In this machine, as in the case of the Daniels planing machine, the work is secured to the table, which travels to carry the work to the feed.

[Fig. 3187] represents a machine by J. Richards, in which a cutter head with skew cutters is employed, and a pressure roll is placed in front and at the back of the cutter head, the construction being as follows:

VOL. II.TRYING‑UP MACHINE.PLATE XXVI.
Fig. 3187.

Upon the main frame are the slideways t, t′, upon which the cross-head or cutter head frame z is carried, the elevating screw s raising or lowering the frame z, to suit the thickness of the work. The cutter head c, whose driving pulleys are shown at p, p, is carried in frame z, which also carries the pressure roll in front of the cutter (the bearing for this roll being shown at r), and a similar roll behind the cutter. To the frame z are pivoted the pressure bars b, b′, weighted with weights w. These bars rest on the cross-heads y, whose pins p act on the bearing boxes of the pressure rolls.

Fig. 3188.

The cutter head frame may be raised or lowered, for varying thicknesses of work, either by hand or by power. The hand movement is obtained from the hand wheel w, [Fig. 3188], which operates bevel gears b′′ and b′, the latter being threaded to receive the elevating screw.

The power or belt motion for raising or lowering the cutter head frame is obtained from rope wheel w′, which receives motion from the guide pulleys shown in [Fig. 3187]. The wheel w′ drives its shaft by the friction cone of its bore, which is forced against the corresponding cone on the shaft by the hand nut l. The handle v, [Fig. 3187], is for operating the upper guide pulley q, which acts as a belt-tightening pulley as well as a guide pulley, and the hand wheel t holds v in its adjusted position. When v is pushed downwards the rope (e) is loosened upon the pulleys, and both rope and pulleys remain idle.

The pulley that drives rope e is shown in [Fig. 3189] at r.

Fig. 3189.

The feed motions for the work table are shown in [Fig. 3189], and the construction is such that for ordinary work the table has a quick return motion, while for heavy work the feed and return motions of the table are speeded alike.

The driving pulley b, [Fig. 3189], for operating the feed mechanism, receives motion by belt connection from the countershaft, and drives the shaft on which are the bevel gears b and d, and from these gears the feed motion and quick return are derived, while from gear e and pulley r the cutter head may be raised and lowered by belt power as occasion may require. Beginning with the feed motion, the gear d drives gears e and f, which are a working fit on the shaft s. Between these two gears is the clutch r, r, which is operated by the handle shown in the perspective view, [Fig. 3187], at v.

To operate the feed, clutch r is operated to engage gear e with the shaft s, upon which is the friction wheel m, which engages with the internal surface of the wheel or drum g, which drives the rope wheel a, which drives the rope for the work table traverse—wheel a and the rope being seen in the perspective view, [Fig. 3187]. The shaft n has bearing in a piece that is virtually a sleeve eccentric, because its bore is eccentric to its circumference; to this sleeve is attached a lug h′ to which the handle h, [Fig. 3187], is bolted. Now suppose that handle h is depressed, and then g will partly revolve wheel g and cause it to engage with the friction wheel m, which will drive g, and therefore a.

Diametrally opposite to m is a friction wheel n, which is driven by the bevel gear c, and which is brought into or out of action with g by the eccentric action of sleeve g, it being obvious that when the sleeve g moves g in the direction of n, m is engaged and n disengaged from contact with g. Raising the handle h therefore places n in gear with g, which revolves it in the direction necessary to draw the work table on the back or return stroke.

The return motion of the table is more rapid than the feed motion because gear c is of smaller diameter than b, and n is larger than c and than m.

In the case of heavy work, however, the return motion may be made to have the same speed as the feed motion by simply moving the clutch r so as to engage wheel f with the shaft s.

The rope groove in the pulley a is waved as denoted by the dotted lines, and this prevents the rope from slipping, notwithstanding that the rope envelops but half the circumference of a. The wire rope from a operates a drum, in which are waved grooves for the table traversing rope which winds around this drum, and attaches to pins (k, [Fig. 3187]) carried in brackets at the ends of the table, and one of which is shown in [Fig. 3187], at z.

The slack of the rope is readily taken up (as occasion may require) as follows:

The pin k, to which the rope is fastened, has at one end a squared head to receive a wrench to revolve the pin and wind up the rope, set screw l locking the pin after the rope tension is adjusted.

We have now to explain the method of holding the work, which is as follows:

The side frames forming the bed are bolted to the main frame and form the ways on which the work table travels. The table frame j, [Fig. 3187], is provided with rollers, which rest on the upper surface of the bed and reduce the friction.

Fig. 3190.

The table is made in convenient sections bolted to the table frame j, and at their points of junction the work-holding dogs are placed, the construction being shown in [Fig. 3190], in which t′ is the end of one, and t′′ the end of another section of the table. Referring now to [Figs. 3187] and [3190], upon the edge of the table are the abutment pieces a′, a′′, against which the work is pulled by the dog, which is operated by the screw, which is squared at its outer end to receive the handle m, [Fig. 3187].

The rate of work feed is 30 feet per minute and the quick return motion is 60 feet per minute.

MOULDING MACHINES.

In moulding machines for light work the feed rolls and cutter head overhang the frame, such machines being designated as outside moulding machines.

[Fig. 3191] represents a machine of this class constructed by J. A. Fay & Company.

Fig. 3191.

The table t slides on vertical ways on the main frame, being adjusted for height by the hand wheel w.

The work while fed over table t is pressed against the vertical face a by the four springs shown, whose pins swing to suit the width of the work.

The two feed rolls are made up in sections or discs and the pressure bar is pivoted and has the weight shown to adjust its pressure to suit the work, and is combined with the bonnet whose shape throws the shavings outwards from the side of the machine. The particular machine here shown is constructed substantially enough to permit of its being used for light planing or work not exceeding 6 inches in width, a head with planing knives being shown in place on the machine. In a machine of this kind it is essential that the cutter head spindle and its bearings be rigid, and with ample journal bearings and free lubrication to prevent wear, and for these reasons the arbor is of steel running in self-oiling bearings of large diameter. The arbor frame is capable of lateral movement to enable an accurate adjustment of the cutters to the work.

The term sticker, as applied to a machine of this class, means that it is suitable for light work such as window sash and door stiles, blind slats, etc., etc.

Fig. 3192.

[Fig. 3192] represents a machine termed by its manufactures (the Egan Company) a “double head panel raiser and double sticker combined.” The term panel raiser means that the edges of the work may be dressed down so as to leave a raised panel. To fit the machine for such work the bed or table t is made wide.

The upper feed rolls are in sections, and the lower one extends nearly across the bed. The upper feed rolls are held down by a spring, whose tension may be regulated by a hand wheel with an adjustment at the back end to give a lead to both rolls. By this is meant that the plane of revolution of the feed rolls inclines toward the cutter head so that as the rolls feed they exert a pressure on the work, holding it securely against the face a.

A long spring extends from the front of the feed rolls past the back or bottom cutter head, passing as shown beneath the pressure bar, and is adjustable for height from the bed or table face t by having its ends pass through two studs in which they may be secured by set screws. This serves to keep the work down to the surface of t.

The cutter heads for panelling have three cutters set askew or at an angle to their plane of revolution so as to give a more continuous and a shearing cut, which is conducive to smooth work.

The bed above the lower cylinder is adjustable for height by means of the screw at h.

MOULDING CUTTERS.

In the ordinary or common form of moulding cutter, the front face is flat and the lower end is bevelled off and filed to shape so as to give the required shape and keenness to the cutting edges, [Fig. 3193] giving examples of such cutters.

Fig. 3193.

Cutters of this class must be sharpened by filing the bevelled edge, which requires considerable skill in order to preserve the exact shape of the moulding.

SOLID MILLED CUTTERS.

Fig. 3194. Fig. 3195.

In the solid milled cutter the bevelled surface at the cutting end of the cutter is a plane, and a curved, stepped or other shape is given to the cutting edge by cutting or milling suitably shaped recesses on the front face of the cutter as shown in [Figs. 3194] and [3195], the former being a tongue cutter for cutting a groove, and the latter a grooved cutter for cutting a tongue.

Fig. 3196. Fig. 3197.

Other examples for such cutters are given as follows:

[Fig. 3196] represents a cove cutter and [Fig. 3197] an ogee. [Fig. 3198], a double beading, and [Fig. 3199] a bevel cutter, and it is obvious that by a suitable arrangement and shape of groove cutting edges of any of the ordinary forms may be produced.

Fig. 3198. Fig. 3199.

The advantages of such cutters are that the plain bevelled face or facet of the cutter may be ground (to sharpen the cutter) on an ordinary emery wheel or grindstone, and the shape of the cutting edge will remain unaltered, providing that the cutter is always held to the grinding wheel or stone at the same angle, so that the length of the bevel remains the same.

A common practice is when making the cutter to so regulate the depth of the grooves or recesses in its face that the cutting edge will be of the required shape when the length of the bevelled facet is equal to three times the thickness of the cutter.

The method of finding the shape of cutter necessary to produce a given shape of moulding has been fully explained on [pages 80] to [85], Vol. II.

Various forms of side heads are shown in the figures from 3200, to 3207. [Fig. 3200] is a two-sided plain head, or in other words two diametrally opposite sides of the head are provided with bolt holes, for cutter fastening bolts. [Fig. 3201] represents a four-sided slotted head, each side having T grooves, so that the cutter may be adjusted endways on the head. This enables the use of four narrow cutters, thus taking the cut in detail as it were.

Fig. 3200. Fig. 3201. Fig. 3202. Fig. 3203.

The two-sided head shown in [Fig. 3202] is provided with a set screw, by means of which a delicate adjustment of the height of the cutter may be made. [Fig. 3203] represents a three-sided slotted head, or in other words T-shaped grooves, and not bolt holes are used.

CUTTER HEADS WITH CIRCULAR CUTTERS.

Fig. 3204.

This form of cutter head was invented by S. J. Shimer, and are generally known as Shimer cutter heads. The principle of construction is shown in [Fig. 3204], which is for an ogee door pattern.

The cutters are circular in form and are seated at an angle to the flange to which they are bolted, this angle giving side clearance to the cutting edges.

Fig. 3205.

Fig. 3206.

The full amount of cut is taken in successive stages or increments; thus in the figure, the two upper cutters would produce one half the moulding, and the two lower ones the lower half. As the cutters are sharpened by grinding the front face, therefore they will maintain correct shape until they are worn out. [Fig. 3205] represents a Shimer head for producing the tongue, and [Fig. 3206] a similar head for producing the groove of matched boards.

Fig. 3207.

[Fig. 3207] shows the action of the groove head, the cutter or bit d being shown in full lines and the second cutter being shown in dotted lines. Cutter d, it will be seen, operates on one half of the groove, and cutter c on the other half, each cutter having side clearance, because of being seated on a seat whose plane is not at a right angle to the axis of revolution of the head.

By thus taking the cut in detail, the head works steadily, while the side clearance makes the cutters cut clean and clear.

JOINTING MACHINE.

“Jointing” a piece of wood or timber, means producing a surface, so that the joint between two pieces that are to come together or be glued shall be close. In order to produce surfaces that shall be true enough for this purpose, it is necessary that the work be held in such a way that it is not sprung or deflected by the holding devices or feeding apparatus.

Fig. 3208.

[Fig. 3208], for example, represents a jointing machine, in which the work abuts against an inclined plate p at one end, while the other end is clamped down to the table, which is traversed past the revolving head h, to which are secured two gouge-shaped cutting tools, one of which is seen at t. By using tools of this class, the amount of cutting edge in action is small, and will not therefore spring the work, and if the cutter spindle is adjusted to have no end motion, the work will be true, notwithstanding any slight vibration of the head, because its plane of revolution coincides with the plane of the surface being surfaced or jointed.

Fig. 3209.

In some jointing machines, knives are set on the face of a revolving disc, an example of this class of machine being shown in [Fig. 3209], which is for facing the spokes of wheels and for finishing the mitre joint on them.

Three cutters are used, each being set at an angle to a radial line, so that the inner edge of the knife will meet the work first. This gives the knives a shearing cut, and prevents the whole of the cutting edge from striking the work at once. The spokes are placed against a stop on the table, and brought into contact with the cutters by the foot treadle.

The table has beneath it a spiral spring at each end, which returns the table as soon as the foot pressure is released from the treadle. The cutter head or disc is 10 inches in diameter, and should make 2,000 revolutions per minute.

Fig. 3210.

Stroke jointers are machines (such as shown in [Fig. 3210]) in which a long plane e of the ordinary hand plane type is worked along a slide by a connecting rod c, operated by a crank motion. A machine of this class will do very accurate work, but is obviously suitable for thin work only.

Fig. 3211.

A machine constructed by J. J. Spilker, for cutting mitre joints by hand, is shown in [Fig. 3211]. The frame a carries a slideway for the slide to which the mitre cutting knife k is secured. The handle g operates a pinion gearing into a rack, which gives vertical motion to the slide and knife. At c is a fence or gauge against which the work is rested, and which is capable of a horizontal motion, so as to bring the work more or less under the knife. For heavy work, the fence c is set back, so that the first cut of the knife will leave the moulding, as shown at h, partly severed, and a second cut is necessary to sever it; for very fine work, a fine shaving may be taken off by a cut taken on the end of each piece separately, after the piece is severed. At d is a graduated scale or rule for cutting the work to exact dimensions, and as its lines are ruled parallel to the right hand edge of the knife k, the inside measurements of a mitre joint may be taken at the outer edge, and outside measurements at the inner end of each line, a set stop at e serving to gauge the pieces for length.

MOULDING OR FRIEZING MACHINES.

These are machines that cut mouldings on the edges of the work. The term friezing is applied by some, when the machine has but one cutter spindle, while by others these machines, whether having one or two spindles, are termed edge moulding machines. Still another term applied to this class of machine is that of variety moulders or variety moulding machines.

In machines of this class, it is of primary importance that lost motion or play in the bearings be avoided, because the cutter end of the spindle overhangs its bearings, and any side play of the spindle in its bearings is multiplied at the cutting edges of the cutters. Perfect lubrication of the spindle bearings, and ample bearing surface on the journals and bearings, are therefore of the first importance.

The work is rested on the upper surface of the table, and is fed to the cutters by hand.

Fig. 3212.

Fig. 3213.

[Figs. 3212] to [3215] represent a machine by J. S. Graham. The frame b, b, [Fig. 3213], of this machine is cast in one piece cored out, and the base is wide, so as to give necessary solidity. The hollow column is fitted with a door w, and shelves v, v, forming a very complete case for the reception of tools, cutters, etc. The spindle boxes and slides c are one casting. They are planed on centres and held in the frame b′, [Fig. 3215], by large gibs l, and sliding surfaces shown in c′, [Fig. 3214]. They are adjustable vertically by hand wheels k, in front of frame in connection with nut o, as shown in [Fig. 3214], and require no lock to hold them at the proper height.

Fig. 3214.

Fig. 3215.

The cap o′ ([Fig. 3213]) has an oil chamber j and wick which feeds the oil to the upper bearing. The lower box is fitted with a patent self-oiling and adjustable step shown at a, b, c. The cap a, upon which the spindle d rests, has a small opening in the centre. The circular block b, under it, also has a hole in the centre. The bolt d has two holes in it, one horizontal and the other vertical.

The chamber surrounding this step and cup is filled with oil. The motion of the spindle d on the cap a causes the oil to flow from the chamber through the openings to the spindle. Thus the oil is kept in constant circulation. The end of this spindle d is by this arrangement kept always lubricated.

The spindles d are of 17⁄8 hammered tool steel accurately turned and fitted in the boxes, which are of extra length, and lined with the best genuine Babbitt metal. They are 30′′ from centre to centre, and have independent screw tops, as shown at s, enabling the operator to use various sizes for large or small work, or clear the table of either spindle for special work.

h is the threaded part of the screw top, g is the nut, and f the fill-up collars.

The iron table a, a is 5 feet by 4 feet, planed and fitted with concentric rings e, e around the spindle, to suit the various sizes of heads and cutters. A heavy wooden table, made of narrow glued-up strips of hard wood, can be used if preferred.

This machine has been run up to 6,000 revolutions per minute, without perceptible jar, and cutter heads as large as 8′′ diameter may be used on it for heavy work.

Fig. 3216.

[Fig. 3216] represents an edge moulding machine by J. H. Blaisdell. In this machine the table is raised or lowered by the hand wheel upon the central column. The construction of the spindle and its bearings is shown in the [sectional view], which also shows the square threaded screw by means of which the table is raised. The spindle has a coned hole for receiving the cutter sockets, which are therefore readily removable.

Fig. 3217.

[Figs. 3217] to [3220] represent examples of the shapes of cutters for use on edge moulding or friezing machines. [Fig. 3217] represents a cutter for bevelling the edge of the work, the cutting edges being at a, b, or at c, d, according to the direction in which the cutter is revolved.

Fig. 3218.

[Fig. 3218] represents an ogee cutter, in position on the cutter spindle. As these cutters are made solid and accurately turned in the lathe, they are balanced so long as the cutting edges are kept diametrally opposite. The front faces only being ground to sharpen the cutting edges, the cutter always produces work of the same shape.

Fig. 3219.

[Fig. 3219] represents a cutter (in a chuck) for cutting a dove-tailed groove, and [Fig. 3220] one for rounding an edge, it being obvious that a wide range of shapes may be given to such cutters, and that, as they may be sharpened on an emery wheel, they may be left comparatively hard, thus enhancing their durability.

Fig. 3220.

To regulate the depth to which a cutter such as shown in [Fig. 3220] will cut, a collar or washer is placed beneath it to act as a guide to the edge of the work.

Fig. 3221.

[Fig. 3221] represents a machine in which rotary cutters are used to produce all kinds of panel work, as well as edge moulding or friezing. In this case the cutter is above the table, the latter being adjustable for height to suit the thickness of the work. Examples of some of the work are shown at the foot of the machine.

WOOD BORING MACHINES.

The rapidity with which holes may be bored in wood enables the feed to be most expeditiously performed by hand or by foot motion. A foot motion leaves both the workman’s hands free to adjust and change the work, and is therefore suitable for light work or work having holes of a moderate depth.

The work tables of wood boring machines are provided with suitable fences for adjusting the work in position, and in some cases with stops to adjust the depth of hole.

Any of the augers or bits that are used in boring by hand may be used in a boring machine, but it is obvious that, as the bit or auger is forced to its feed by hand or foot, and as its revolution is very rapid, the screw point, which is intended as an aid in feeding when the bit is used by hand, is not necessary. On this account most augers for use in machines are provided with triangular points instead of screw points.

Fig. 3222.

In [Fig. 3222] is shown a wood boring machine by J. A. Fay & Co. The table is gibbed to a vertical slide on the face of the column, and is adjustable for height by the hand wheel a, which, through the medium of its shaft and a pair of bevel gears, operates the elevating screw b. The spindle c feeds through its bearings, the supporting rod d being pivoted at its lower end to permit c to feed in a straight line vertically. The feeding is done by the treadle f, which operates the rod e.

The table may be set at an angle of 30 degrees from the horizontal position.

The weight w counterbalances the treadle and brings it to its highest position when the workman’s foot pressure is removed.

The holes may all be gauged to an equal depth (when they are not to pass through the work) by so adjusting the height of the table that the hole is of the required depth when the treadle is depressed to its lowest point, or limit.

Fig. 3223.

[Fig. 3223] represents a horizontal boring machine such as used in furniture and piano factories. The spindle feeds through the driving cone, being operated by the treadle shown. The work table is adjustable for height by the hand wheel and elevating screw. The usual fences, stops, and clamping devices may be applied to the table, which is on compound slides to facilitate the adjustment of the work.

Fig. 3223a.

[Fig. 3223a] shows a double spindle horizontal boring machine, in which the table and work are fed up to the boring tools by hand. The spindles are adjustable in their widths apart, and may also be set at an angle. The work table is adjustable for height, and the spindle carrying head is adjustable across the machine.

Fig. 3224.

[Fig. 3224] represents a machine by J. A. Fay & Co., for heavy work, rollers taking the place of the work table. The drill spindles are fed by hand from the stirrup handles shown, which are weighted to raise up the spindles as soon as they are released.

MORTISING MACHINES.

The mortising machine for wood work consists essentially of an ordinary auger, which bores the holes, and a chisel for cutting the corners so as to produce the square or rectangular mortise that is usually employed in wood work.

The chisel is reciprocated and its driving spindle is provided with means whereby the chisel may be reversed so as to cut on either the sides or the ends of the mortise. The chisel is fed gradually to its cut.

Fig. 3225.

[Fig. 3225] represents a mortising machine for the hubs of wheels.

The auger spindle is here fed vertically by a hand lever, the depth bored being regulated by a rod against which the hand lever comes when the hole is bored to the required depth.

Fig. 3226.

[Fig. 3226] represents a mortising machine in which the mortising tool consists of a hollow square chisel containing an auger, and having at its sides openings through which the cuttings escape.

The chisel is rectangular in cross section, but its cutting edges are highest at the corners, as may be clearly seen in the figure.

The work is firmly clamped to the work table and simultaneously to the fence, the upper hand wheel being operated to bring the work-holding clamp down to the work, and the lower one to clamp it so as to press it to both the table and the fence at the same time.

The chisel bar is mounted horizontally in a slide way on a substantial bed that is mounted on a vertical slideway, which enables the chisel bar to be set for height from the work table. It has a horizontal traverse motion or feed, the amount of this motion being governed by the horizontal rod with its nuts and check nuts as shown.

The auger runs continuously, and works slightly in advance of the cutting edge of the chisel, which is passive except when making the mortise.

The chisel bar and auger have a slow, reciprocating motion, and will complete a hole the size of the chisel used. An inch chisel will cut an inch-square hole, consequently a mortise 1′′ × 4′′ would only require four strokes forward to complete it. It has a capacity to work mortises from 3⁄4′′ to 3′′ square, and 5′′ in depth, and any length desired. The boring spindle is driven by an idler pulley, direct from the countershaft.

The bed upon which the timber is placed to be mortised is gibbed to a sliding frame, which allows it to be set to any position, with the chisel straight or at an angle. It is adjustable to and from the chisel bar, to suit the size of material, the under side of which always remains at one height. Adjustments are provided for moving the carriage forward, for regulating the depth of the mortise, the position of the chisel from the face of the material, and the adjustment of the chisel bar, controlling the mortises to be made in the timber.

Two treadles are used upon the side of the machine; the pressure upon one carrying the chisel bar attachment forward, completing the mortise, while the other will instantly force it back when it is desired to withdraw it from the wood, without allowing it to cut its full depth. Provision is made by stops for regulating the length of the stroke as well as the depth of the mortise.

TENONING MACHINES.

In tenoning machines, the lengths of the pieces usually operated upon render it necessary that the work should lie horizontally upon the table, while the shortness of the tenon makes an automatic feed unnecessary.

The revolving heads carrying the cutters in tenoning machines are so constructed that the cutting edges of the cutters are askew to the sides of the heads, but so set as to produce work parallel to the axis of the cutter shaft.

This causes the cutting action to begin at one end of the cutter edge, and pass along it to the other, which enables a steady hand feed, and reduces the amount of power required to feed the work.

Fig. 3227.

[Fig. 3227] represents a cutter head for a tenoning machine, a, a and b, b being the cutters and c, c, d, d spurs which stand a little farther out than the cutter edges, so as to sever the fibre of the wood in advance of the cutter edges coming into action, and thus preserve a sharp shoulder to the tenon, and prevent the splitting out at the shoulder that would otherwise occur.

Fig. 3228.

To bring the outer edge of the shoulder in very close contact with the mortised timber, the cutters are for some work followed by what is termed a cope head, which is a head carrying two cutters bent forward as in [Fig. 3228], to make them cut very keenly, as is necessary in cutting the end grain of wood.

Fig. 3229.

The cope head undercuts the shoulder, as shown at a, a, in [Fig. 3229], which is a sectional view of a mortise and tenon.

[Large
image
(263 kB).]

Fig. 3230.

[Fig. 3230] represents a tenoning machine for heavy work, constructed by J. A. Fay & Co., adjusted for cutting a double tenon, the upper and lower heads revolving in a vertical plane, and the middle head in a horizontal plane.

a is a vertical slideway for the heads c, d, carrying the shafts for the cutter heads a, b. At b is the hand wheel for adjusting d, and at e that for adjusting c. The pulley d is for driving the cope heads, one of whose cutters is seen at c. The work carriage h is provided with rollers which run on the slide on k, and is supported by the arm i, which rises and falls to suit the cross motion of h. The fence g, for the work, is adjustable by means of the thumb nuts.

SAND-PAPERING MACHINES.

Sand-papering machines are of comparatively recent introduction in wood working establishments, but are found very efficient in finishing surfaces that were formerly finished by hand labor.

Fig. 3231.

[Fig. 3231] represents a sand-papering machine, by P. Pryibil, in which a spindle has three stepped cones on one end, and a parallel roller or cylinder at the other. The steps on the spindle are covered with a rubber sleeve, and the sand paper is cut to a template, and the edges brought together and joined by gluing a strip of tough paper under them. When this has become dry the paper is slightly dampened everywhere except at the joint, and is then slipped on the taper drums. In drying it shrinks and becomes tight and smooth upon the rubber covering with which the drums are provided. These are of different sizes to fit different curves in the work.

Flat work is done upon the table, which is hinged and provided with an adjusting screw to regulate its height, and it can be raised to give access to the drum.

When sand paper is applied in this way, every grain is brought into contact with the work, whereas at first only the larger grains cut when it is used on the faces of revolving discs, as in some machines of this class. Furthermore, when used on drums it is offered ample opportunity to clear itself of dust; it therefore does not become clogged, and, as a consequence, it lasts longer and does more and better work than when used on discs.

Fig. 3232.

[Fig. 3232] represents a similar machine, but having a spindle vertical also, so that one face of the work can be laid on the table, which acts as a guide to keep the work square, the table surface being at a right angle to the vertical spindle.

The vertical cylinder or drum is split on one side, and provided with internal cones, so, that by screwing down the nut shown the drum can be expanded to tightly grip the sand paper, which is glued and put on as already described.

Besides these rotary motions, these drums receive a slow vertical motion, the amount of which is variable at the operator’s pleasure. This provides for using the full face of the drum on narrow work, while it prevents the formation of ridges or grooves in the work.

For sand-papering true flat surfaces the flat table is provided, there being beneath it a parallel revolving drum, whose perimeter just protrudes through the upper surface of the table. The surface of the table thus serves as a guide to steady the work while the sand-papering is proceeding.

By using sand paper in this manner, every grain of the sand is brought into contact with the work; furthermore, a small area of sand paper is brought into contact with the work, and the wood fibre can fly off and not lodge in the sand paper; while at the same time the angles of the grains of sand or glass are presented more acutely to the work, and therefore cut more freely and easily. Hence the sand paper lasts much longer, because a given pressure is less liable to detach the sand from the paper.

The machine is constructed entirely of iron, and the drum is intended to revolve at about 800 revolutions per minute.

Fig. 3233.

[Fig. 3233] represents a sand-papering machine in which a long parallel cylinder is employed, the work resting on the surface of the table and being fed by hand. In using a machine of this class the work should be distributed as evenly as possible along all parts of cylinder, or one end of the cylinder may become worn out while the other is yet sharp; this would incapacitate the machine for wide work unless a new covering of sand paper were applied.

Fig. 3234.

[Fig. 3234] represents a sand-papering machine constructed by J. A. Fay & Co., for finishing doors and similar work. The frame constitutes a universal joint enabling the sand paper disc to be moved anywhere about the door by hand. An exhaust fan on the top of the main column removes the dust from the work surface. The head carrying the disc is moved vertically in a slideway to suit different thicknesses of work.

VOL. II.SANDING MACHINES.Plate XXVII.
Fig. 3235.
Fig. 3236.

[Fig. 3235] represents a self-feeding sand-papering machine constructed by J. A. Fay & Co. It is made in three sizes, to work material either 24′′, 30′′, or 36′′ wide by 4′′ thick and under; it has a powerful and continuous feed, and gives to the lumber a perfect surface by once passing it through the machine.

The feeding mechanism consists of six rollers, in three pairs, driven by a strong train of gearing. The upper feeding rollers, with the pressure rollers over the drum are lifted together in a perfect plane by the movement of four raising screws, operated by a chain and hand wheel. The lower feeding rollers always remain in perfect line with the drums.

It is supplied with two polishing cylinders, placed in the body of the machine, on which the upper frame rests, both having a vibratory lateral motion for removing lines made by irregularities in the sand paper. The finishing cylinder is placed so that the discharging rollers carry the lumber from it, thus running through and finishing one board, if desired, without another following, and these rollers are arranged for a vertical adjustment to suit the dressed reduction on the material to be worked. The roughing cylinder carries a coarse grade of sand paper, and the finishing one a finer grade. They may be driven in opposite or in the same direction, as may be necessary. The lower frame is hinged at each end to the upper frame, so that by removing a pin, either cylinder can be reached by raising the frame with the screw and worm gear, operated by a hand wheel at the end of the machine.

A brush attachment (not shown in the cut) is now placed at the end of the machine just beyond the finishing cylinder, which is a most complete device for brushing the material clean after it leaves the sand-papering cylinders.

[Fig. 3236] represents a double wheel sanding machine by J. A. Fay & Co.

This machine is intended for accurately finishing the tread of the wheel ready for the tire, and is one of the most useful and labor-saving machines that can be placed in a wheel shop.

The frame is built entirely of iron, and has a heavy steel arbor running in long bearings, with tight and loose pulleys in the centre. On each end of the arbor is a large sand paper disc for polishing the tread of the rim.

The wheel to be finished is laid on a rotating carrying frame, having two upright drivers. These are attached to a jointed swinging frame, with flexible connections, adjustable to suit wheels of varying diameters.

The first section of the jointed frame is driven by a shaft and bevel gears, and swings upon it. The second one has the wheel-carrying frame, and swings upon the extreme end of the first one, and is driven from it by a chain connection.

A roller wheel is secured at the bottom of the leg, affording a floor support; also a chain to regulate the proper distance of the wheel from the discs.

A wrought iron supporting frame is attached upon each side of the sand paper discs, adjustable for different sizes.

The wheel when placed in the machine is carried by the gearing against the sand paper discs, which finishes the tread in the most accurate and perfect manner.

Machines are made both single and double. The latter are the most desirable, as the operator has only to place a wheel in position on one side, when it feeds and takes care of itself.

By the time this is done, the wheel on the opposite side will be finished and ready to be removed, when a fresh one is put in, and the operation continued, the only care required being to put in and remove them. Its capacity is 150 set of wheels per day, and it will do the work better than can be done by hand.