PUTTING IN A NEW CYLINDER.
Putting in a new cylinder is something most watchmakers fancy they can do, and do well; but still it is a job very few workmen can do and fulfill all the requirements a job of this kind demands under the ever-varying conditions and circumstances presented in repairs of this kind. It is well to explain somewhat at this point: Suppose we have five watches taken in with broken cylinders. Out of this number probably two could be pivoted to advantage and make the watches as good as ever. As to the pivoting of a cylinder, we will deal with this later on. The first thing to do is to make an examination of the cylinder, not only to see if it is broken, but also to determine if pivoting is going to bring it out all right. Let us imagine that some workman has, at some previous time, put in a new cylinder, and instead of putting in one of the proper size he has put one in too large or too small. Now, in either case he would have to remove a portion of the escape-wheel tooth, that is, shorten the tooth: because, if the cylinder was too large it would not go in between the teeth, and consequently the teeth would have to be cut or stoned away. If the cylinder was too small, again the teeth would have to be cut away to allow them to enter the cylinder. All workmen have traditions, rules some call them, that they go by in relation to the right way to dress a cylinder tooth; some insisting that the toe or point of the tooth is the only place which should be tampered with. Other workmen insist that the heel of the tooth is the proper place. Now, with all due consideration, we would say that in ninety-nine cases out of a hundred the proper thing to do is to let the escape-wheel teeth entirely alone. As we can understand, after a moment's thought, that it is impossible to have the teeth of the escape wheel too long and have the watch run at all; hence, the idea of stoning a cylinder escape-wheel tooth should not be tolerated.
ESCAPE-WHEEL TEETH vs. CYLINDER.
It will not do, however, to accept, and take it for granted that the escape-wheel teeth are all right, because in many instances they have been stoned away and made too short; but if we accept this condition as being the case, that is, that the escape-wheel teeth are too short, what is the workman going to do about it? The owner of the watch will not pay for a new escape wheel as well as a new cylinder. The situation can be summed up about in this way, that we will have to make the best we can out of a bad job, and pick out and fit a cylinder on a compromise idea.
In regard to picking out a new cylinder, it may not do to select one of the same size as the old one, from the fact that the old one may not have been of the proper size for the escape wheel, because, even in new, cheap watches, the workmen who "run in" the escapement knew very well the cylinder and escape wheel were not adapted for each other, but they were the best he had. Chapter II, on the cylinder escapement, will enable our readers to master the subject and hence be better able to judge of allowances to be made in order to permit imperfect material to be used.
In illustration, let us imagine that we have to put in a new cylinder, and we have none of precisely the proper size, but we have them both a mere trifle too large and too small, and the question is which to use. Our advice is to use the smaller one if it does not require the escape-wheel teeth to be "dressed," that is, made smaller. Why we make this choice is based on the fact that the smaller cylinder shell gives less friction, and the loss from "drop"—that is, side play between the escape-wheel teeth and the cylinder—will be the same in both instances except to change the lost motion from inside to outside drop.
In devising a system to be applied to selecting a new cylinder, we meet the same troubles encountered throughout all watchmakers' repair work, and chief among these are good and convenient measuring tools. But even with perfect measuring tools we would have to exercise good judgment, as just explained. In Chapter II we gave a rule for determining the outside diameter of a cylinder from the diameter of the escape wheel; but such rules and tables will, in nine instances out of ten, have to be modified by attendant circumstances—as, for instance, the thickness of the shell of the cylinder, which should be one-tenth of the outer diameter of the shell, but the shell is usually thicker. A tolerably safe practical rule and one also depending very much on the workman's good judgment is, when the escape-wheel teeth have been shortened, to select a cylinder giving ample clearance inside the shell to the tooth, but by no means large enough to fill the space between the teeth. After studying carefully the instructions just given we think the workman will have no difficulty in selecting a cylinder of the right diameter.
MEASURING THE HEIGHTS.
The next thing is to get the proper heights. This is much more easily arrived at: the main measurement being to have the teeth of the escape wheel clear the upper face of the lower plug. In order to talk intelligently we will make a drawing of a cylinder and agree on the proper names for the several parts to be used in this chapter. Such drawing is shown at Fig. 171. The names are: The hollow cylinder, made up of the parts A A' A'' A''', called the shell—A is the great shell, A' the half shell, A'' the banking slot, and A''' the small shell. The brass part D is called the collet and consists of three parts—the hairspring seat D, the balance seat D' and the shoulder D'', against which the balance is riveted.
The first measurement for fitting a new cylinder is to determine the height of the lower plug face, which corresponds to the line x x, Fig. 171. The height of this face is such as to permit the escape wheel to pass freely over it. In selecting a new cylinder it is well to choose one which is as wide at the banking slot A'' as is consistent with safety. The width of the banking slot is represented by the dotted lines x u. The dotted line v represents the length to which the lower pivot y is to be cut.
There are several little tools on the market used for making the necessary measurements, but we will describe a very simple one which can readily be made. To do so, take about a No. 5 sewing needle and, after annealing, cut a screw thread on it, as shown at Fig, 172, where E represents the needle and t t the screw cut upon it. After the screw is cut, the needle is again hardened and tempered to a spring temper and a long, thin pivot turned upon it. The needle is now shaped as shown at Fig. 173. The pivot at s should be small enough to go easily through the smallest hole jewel to be found in cylinder watches, and should be about 1/16" long. The part at r should be about 3/16" long and only reduced in size enough to fully remove the screw threads shown at t.
We next provide a sleeve or guard for our gage. To do this we take a piece of hard brass bushing wire about 1/2" long and, placing it in a wire chuck, center and drill it nearly the entire length, leaving, say, 1/10" at one end to be carried through with a small drill. We show at F, Fig. 174, a magnified longitudinal section of such a sleeve. The piece F is drilled from the end l up to the line q with a drill of such a size that a female screw can be cut in it to fit the screw on the needle, and F is tapped out to fit such a screw from l up to the dotted line p. The sleeve F is run on the screw t and now appears as shown at Fig. 175, with the addition of a handle shown at G G'. It is evident that we can allow the pivot s to protrude from the sleeve F any portion of its length, and regulate such protrusion by the screw t. To employ this tool for getting the proper length to which to cut the pivot y, Fig. 171, we remove the lower cap jewel to the cylinder pivot and, holding, the movement in the left hand, pass the pivot s, Fig. 175, up through the hole jewel, regulate the length by turning the sleeve F until the arm of the escape wheel I, Fig. 176, will just turn free over it. Now the length of the pivot s, which protrudes beyond the sleeve F, coincides with the length to which we must cut the pivot y, Fig. 171. To hold a cylinder for reducing the length of the pivot y, we hold said pivot in a pair of thin-edged cutting pliers, as shown at Fig. 177, where N N' represent the jaws of a pair of cutting pliers and y the pivot to be cut. The measurement is made by putting the pivot s between the jaws N N' as they hold the pivot. The cutting is done by simply filing back the pivot until of the right length.
TURNING THE PIVOTS.
We have now the pivot y of the proper length, and what remains to be done is to turn it to the right size. We do not think it advisable to try to use a split chuck, although we have seen workmen drive the shell A A''' out of the collet D and then turn up the pivots y z in said wire chuck. To our judgment there is but one chuck for turning pivots, and this is the cement chuck provided with all American lathes. Many workmen object to a cement chuck, but we think no man should lay claim to the name of watchmaker until he masters the mystery of the cement chuck. It is not such a very difficult matter, and the skill once acquired would not be parted with cheaply. One thing has served to put the wax or cement chuck into disfavor, and that is the abominable stuff sold by some material houses for lathe cement. The original cement, made and patented by James Bottum for his cement chuck, was made up of a rather complicated mixture; but all the substances really demanded in such cement are ultramarine blue and a good quality of shellac. These ingredients are compounded in the proportion of 8 parts of shellac and 1 part of ultramarine—all by weight.
HOW TO USE A CEMENT CHUCK.
The shellac is melted in an iron vessel, and the ultramarine added and stirred to incorporate the parts. Care should be observed not to burn the shellac. While warm, the melted mass is poured on to a cold slab of iron or stone, and while plastic made into sticks about 1/2" in diameter.
We show at Fig. 178 a side view of the outer end of a cement chuck with a cylinder in position. We commence to turn the lower pivot of a cylinder, allowing the pivot z to rest at the apex of the hollow cone a, as shown. There is something of a trick in turning such a hollow cone and leaving no "tit" or protuberance in the center, but it is important it should be done. A little practice will soon enable one to master the job. A graver for this purpose should be cut to rather an oblique point, as shown at L, Fig. 179. The slope of the sides to the recess a, Fig. 178, should be to about forty-five degrees, making the angle at a about ninety degrees. The only way to insure perfect accuracy of centering of a cylinder in a cement chuck is center by the shell, which is done by cutting a piece of pegwood to a wedge shape and letting it rest on the T-rest; then hold the edge of the pegwood to the cylinder as the lathe revolves and the cement soft and plastic. A cylinder so centered will be absolutely true. The outline curve at c, Fig. 178, represents the surface of the cement.
The next operation is turning the pivot to the proper size to fit the jewel. This is usually done by trial, that is, trying the pivot into the hole in the jewel. A quicker way is to gage the hole jewel and then turn the pivot to the right size, as measured by micrometer calipers. In some cylinder watches the end stone stands at some distance from the outer surface of the hole jewel; consequently, if the measurement for the length of the pivot is taken by the tool shown at Fig. 175, the pivot will apparently be too short. When the lower end stone is removed we should take note if any allowance is to be made for such extra space. The trouble which would ensue from not providing for such extra end shake would be that the lower edge of the half shell, shown at e, Fig. 171, would strike the projection on which the "stalk" of the tooth is planted. After the lower pivot is turned to fit the jewel the cylinder is to be removed from the cement chuck and the upper part turned. The measurements to be looked to now are, first, the entire length of the cylinder, which is understood to be the entire distance between the inner faces of the two end stones, and corresponds to the distance between the lines v d, Fig. 171. This measurement can be got by removing both end stones and taking the distance with a Boley gage or a douzieme caliper.
A CONVENIENT TOOL FOR LENGTH MEASUREMENT.
A pair of common pinion calipers slightly modified makes as good a pair of calipers for length measurement as one can desire. This instrument is made by inserting a small screw in one of the blades—the head on the inner side, as shown at f, Fig. 180. The idea of the tool is, the screw head f rests in the sink of the cap jewel or end stone, while the other blade rests on the cock over the balance. After the adjusting screw to the caliper is set, the spring of the blades allows of their removal. The top pivot z of the cylinder is next cut to the proper length, as indicated by the space between the screwhead f and the other blade of the pinion caliper. The upper pinion z is held in the jaws of the cutting pliers, as shown in Fig. 177, the same as the lower one was held, until the proper length between the lines d v, Fig. 171, is secured, after which the cylinder is put back into the cement chuck, as shown at Fig. 178, except this time the top portion of the cylinder is allowed to protrude so that we can turn the top pivot and the balance collet D, Fig. 171.
The sizes we have now to look to is to fit the pivot z to the top hole jewel in the cock, also the hairspring seat D and balance seat D'. These are turned to diameters, and are the most readily secured by the use of the micrometer calipers to be had of any large watchmakers' tool and supply house. In addition to the diameters named, we must get the proper height for the balance, which is represented by the dotted line b. The measurement for this can usually be obtained from the old cylinder by simply comparing it with the new one as it rests in the cement chuck. The true tool for such measurements is a height gage. We have made no mention of finishing and polishing the pivots, as these points are generally well understood by the trade.
REMOVING THE LATHE CEMENT.
One point perhaps we might well say a few words on, and this is in regard to removing the lathe cement. Such cement is usually removed by boiling in a copper dish with alcohol. But there are several objections to the practice. In the first place, it wastes a good deal of alcohol, and also leaves the work stained. We can accomplish this operation quicker, and save alcohol, by putting the cylinder with the wax on it in a very small homeopathic bottle and corking it tight. The bottle is then boiled in water, and in a few seconds the shellac is dissolved away. The balance to most cylinder watches is of red brass, and in some instances of low karat gold; in either case the balance should be repolished. To do this dip in a strong solution of cyanide of potassium dissolved in water; one-fourth ounce of cyanide in half pint of water is about the proper strength. Dip and rinse, then polish with a chamois buff and rouge.
In staking on the balance, care should be observed to set the banking pin in the rim so it will come right; this is usually secured by setting said pin so it stands opposite to the opening in the half shell. The seat of the balance on the collet D should be undercut so that there is only an edge to rivet down on the balance. This will be better understood by inspecting Fig. 181, where we show a vertical section of the collet D and cylinder A. At g g is shown the undercut edge of the balance seat, which is folded over as the balance is rivetted fast.
About all that remains now to be done is to true up the balance and bring it to poise. The practice frequently adopted to poise a plain balance is to file it with a half-round file on the inside, in order not to show any detraction when looking at the outer edge of the rim. A better and quicker plan is to place the balance in a split chuck, and with a diamond or round-pointed tool scoop out a little piece of metal as the balance revolves. In doing this, the spindle of the lathe is turned by the hand grasping the pulley between the finger and thumb. The so-called diamond and round-pointed tools are shown at o o', Fig. 182. The idea of this plan of reducing the weight of a balance is, one of the tools o is rested on the T-rest and pressed forward until a chip is started and allowed to enter until sufficient metal is engaged, then, by swinging down on the handle of the tool, the chip is taken out.
In placing a balance in a step chuck, the banking pin is caused to enter one of the three slots in the chuck, so as not to be bent down on to the rim of the balance. It is seldom the depth between the cylinder and escape wheel will need be changed after putting in a new cylinder; if such is the case, however, move the chariot—we mean the cock attached to the lower plate. Do not attempt to change the depth by manipulating the balance cock. Fig. 183 shows, at h h, the form of chip taken out by the tool o o', Fig. 182.