Plate 13.
[Plate 13] contains several specimens of eccentric turning. The temple may be made either of wood or ivory, and be left open, as in the plate, or have a coloured card-board case made to fit inside it. The upper and lower parts of the pillars, six in number, are fluted with a round-ended drill, but the middle parts are worked with the eccentric chuck, and are curious specimens of its powers. They much resemble a spiral staircase, and though at first sight they may appear difficult, yet they are not so when properly explained. Begin by turning the wood or ivory perfectly cylindrical with the slide-rest tool. This done, screw your eccentric chuck one turn downwards, and turn the screw of your rest one turn forwards, moving 12 numbers on the eccentric chuck wheel for every step. As this requires great nicety, delicacy, and care, (the cuts being very deep,) you must no longer depend upon the lever to approach the tool (which is No. 1, of the slide-rest tools) to the work; instead of using it, screw one of the screws, L, at the end of the tool slider, to the deepest cut, and leave it so; then, as you push the tool against the wood, gently unscrew the other screw, L, till the first one prevents its cutting any deeper. For every step, move exactly the breadth of the tool. If the piece you are working is thin and long, it will be necessary to use the back puppet; in which case remember to draw it away from the wood at every change of movement; for, of course, when the eccentric chuck is altered, the centre of the work becomes altered also. Nos. 1 and 2 of [plate 13] are different patterns for pillars, both worked without the eccentric chuck. The depth of the cuts, it will immediately be seen, form the steps. The rings now demand our attention; the tool used for forming them is No. 6 of the slide-rest tools, [plate 5]; one side of the tool cuts the outer; the other, the inner part of the rings. Put the tool into a handle, where it must be held firm by a screw; the same handle will be very useful to hold the slide-rest tools for making mouldings and delicate ornaments. The end of the ring tool, No. 6, being very sharp, cuts a road for itself into the wood or ivory, then press it gently to the left, till you find one half of the ring is formed, which will be seen by its filling up the half circle of the tool; then remove the tool to the outside of the work, and press the other side against it till the ring falls off. It is a good way to turn a small cup and line it with velvet, or some soft article, into which to allow the rings to fall, as the delicate ones would be apt to split by striking against the steel bed of the lathe. To form the chain, cut the rings carefully through on one side with a sharp penknife, and slip them one through the other. The handles of the temple are large rings, the pins they hang upon are of wood. Flatten the knob either with a file or a small saw, and drill a hole through it to receive the ring; the pin is then glued into the moulding.
The ball at the top is turned quite round, and may be ornamented with the circular rest. The ball pendant from the chain is circular, except on one side, where a small pin is left, through which drill a hole and slip the ring through it. All the ornaments, pillars, and flutings may be made of separate small pieces of ivory, which, when worked, are easily fastened together by a strong cement made of isinglass melted in gin. The top of the temple may be worked with the universal cutter, or the drill, and the feet are turned quite round, and then ornamented with the eccentric cutter, as directed for the stopper of the bottle, B, [plate 9]. The needle-case, E, in [plate 13], is also a specimen of curious turning; the whole thing should be of ivory, or else the twists of ivory, and the pillar in the middle of cocoa, or some dark wood. Turn the ivory perfectly cylindrical, and hollow it very carefully; this done, throw your eccentric chuck four times outwards, the screw of the sliding rest one turn downwards, and the eccentric chuck wheel four numbers for each plate. The other twists are each worked exactly the same, and they must have a small pin left at either end, which is glued into the moulding. When your centre pillar is hollowed, fit the twists to it.
Another method for working this pattern is with the aid of the drill, and by this means the twists are in the same piece of ivory as the pillar. Having formed a smooth cylinder, hollowed it out, and made the screws, take your largest flat-ended drill, and drill fifteen holes round the pillar, or one at every eighth number of the eccentric chuck wheel. Your ivory must be very thick, to enable the tool to cut very deep. Having cut one row of holes, slowly and carefully, you must move the sliding rest forward two turns, then cut another hole every eighth number again; do a third circle the same, moving the chuck and slide the same every time. Now examine your work, and see whether the twists begin to appear. They should, as in the plate, be quite separate from the ivory tube in the middle, being only joined at the top and bottom. For this no exact rule can be given, as it depends on the circumference of the work: if very large, the tool must cut very deep to detach it: but, after trying two or three times by these directions, it will be found quite easy. As the ivory twists are, of course, very delicate, and the least jar in working is apt to break, do not use the lever, but employ the screw guides, as directed for the spiral turning. Line the ivory before beginning the twists, and leave about half an inch at each end, which you can ornament with the cutter: this gives strength to the work. For the same reason, it is advisable to cut one piece of your ivory longer than the other: on the shorter one make the outside screw, and below it about half an inch of ornament; on the other, make the inside screw, and work it with the cutter to correspond with the other part, quite beyond where the screw extends. When screwed together, it will not be perceived that the two pieces are not even; and as the part where the inner screw is worked is, of course, thin, you would have no thickness for the spiral pattern. When one end is finished, put a fine double angular tool into your cutter, and very carefully cut some circles at regular distances between the twists: this adds much to the curious effect of the patterns: to do it, work backwards, counting the same numbers on the chuck wheel and on the sliding rest as for the twists.
Patterns that are not cut deep can have the impression taken off on paper, either by slightly rubbing the wood over with printers’ ink, and laying upon it silver paper, which must be pressed down upon it; or by laying the paper on the wood, and rubbing it well with a piece of lead melted into the shape of a pencil. Patterns on ivory also look very well by rubbing a little printers’ ink well over them till the lines are full of it, then wipe off the superfluous ink from the surface, and the design will be black on a white ground.
An immense variety of most beautiful and intricate patterns are worked with the eccentric cutter, in conjunction with the eccentric chuck; indeed, many of those formerly supposed to be only done with the double eccentric chuck, invented by Mr. Ibbetson, can be worked by these two when used together, but they require much patience, and knowledge of the powers of the eccentric chuck, to enable the learner to use them properly. When the eccentric cutter is used, always set the tool exactly in the centre of the work, at its lowest degree, before you begin any pattern, or you will never be quite sure that your work is done straight; when once you have settled the centre, the patterns will diverge regularly and evenly from it. In the patterns we are going to describe, the slide rest fixes the position of the tool; the chuck must be screwed down to the proper situation to meet it, and the cutter tool must then be screwed out to cut the circle required.
PATTERN 1, [PLATE 14.]
This pattern is formed of four groups of circles, containing seven in each. Your wood being perfectly smoothed and lined, set the cutter tool (a double angular one) at its lowest degree, exactly in the centre of the work, so that if moved it would only cut a dot. Unscrew it eight or ten turns to make a large circle, then by impelling the cutter box forwards with the slide-rest screw, fix it so that the tool cuts the circle a little over the centre: arrange your screw guides: having cut one circle, count 30 on the eccentric chuck wheel, and the same for the other two. It will be observed that these four groups go in straight lines, each towards the edge of the work; to perform this, in the six following rows of circles, move the slide rest forwards half a turn, and the small wheel of the eccentric chuck half a turn upwards for each row of four circles, counting 30, as before, till the twenty-eight are all done.