The Clock Jobber's Handybook

By Paul N. Hasluck

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Tick Tock Productions ™

The

CLOCK JOBBER'S HANDYBOOK.

CHAPTER VI

REPAIRING AN 8-DAY CLOCK

Tooth in Clock where the tooth is broken off, a dovetail-shaped wheel piece, similar to that shown in Fig. 45, taking care not to damage the wheel in doing so. The usual saw employed for this purpose is an adjustable bow saw or frame saw, Fig. 46, which takes the saw blades used for piercing metal and for fretwork. Saw blades, much wider mounted in a rigid bow frame, like Fig. 47, and miniature back saws are used more frequently for general work. The saw blade should always be mounted in its frame to cut when pulled, not when being pushed away, slant towards the handle, a little thicker than the wheel, into the dovetail, with enough projecting to form that is to say the teeth should Accurately fit a piece of brass, a new tooth. When this piece is well fitted, scrape off the sharp edges of the dovetail; put in the piece, and rivet it well, so as to make it firm, taking care not to spread or damage the wheel. If the wheel is thin, and liable to be injured by the hammering, it is advisable to put a little tinning fluid to the edges of the piece before putting it in its place ; rivet it slightly, and then neatly run in a little solder. Soldering, in this instance, is better than riveting, because an inexperienced person, and even an experienced one, will sometimes stretch the wheel and put it out of round in the riveting process. Soldering, if a moderate heat be used, does no harm ; and if care has been taken to fit the brass exactly to the dovetail, the solder will not show much when the sides of the wheel are polished. The tooth or teeth may now be formed in the new brass that has been inserted in the wheel, and if done agreeably to the above instructions, the wheel, for all practical purposes, will be equally good as when new. When the new piece is quite firm, file it flush with the wheel on both sides, and file up the tooth to the same shape and size as the perfect ones, midway between the adjoining teeth. Sometimes small holes are drilled in the edge of the wheel, and pins driven in to take the place of teeth. This plan is good as a temporary method, and may be practiced in temporarily repairing a clock which could not at the time be removed to a workshop. But, although proper under such circumstances, it is not to be commended as an example to follow when a clock is being put in thorough repair.

It occasionally happens that more than one tooth is broken out—it may be four or five consecutively—and then considerable difficulty is found in making a good job. The following plan will give a most satisfactory result if carefully followed: Commence by fitting in a suitable piece of brass, as already described. Then procure a slip of zinc, drill a hole through it, and fit it tightly on the pinion or arbor upon which the wheel is mounted. Secure it at a part where the teeth are sound, and cut it to the curve of the wheel; then, with a slitting file or saw, cut out a pattern of several teeth, a few more than you require in the new piece. When the zinc pattern is an exact copy of that part, bring it round to the new piece, allowing two or three of the zinc teeth to coincide with the wheel teeth at both ends of the new piece. Fix it in this position, and the new teeth may be then carefully cut with ease and accuracy. Another method of putting in a new tooth is to drill a hole radially into the rim of the wheel, and tap in a steel wire, which is then filed to the shape of a tooth. This is not such a good plan as the other, and does not look so well, but might be adopted in some peculiar cases as explained above.

For most ordinary clocks, wheels can be purchased in sets ; but better ones are made to order by a wheel-cutter. The teeth will be finished, and require no further attention, unless, perhaps, to remove an occasional burr; but the " crossings " or arms must be carefully filed out to the proper shape, and the side faces of the wheel finished up smooth and fiat. They can be most conveniently " crossed out" before mounting them on their pinions, and the faces best finished after mounting. When the wheels are sufficiently rigid they may be polished by holding rather a wide rubber against them as they revolve in the lathe or " throw." The rubber, which may be either of soft steel or of bell-metal, must be filed crosswise with a medium-coarse file, and then charged with oil-stone dust and oil. When all the file marks are out, clean the rubber thoroughly, file it again, and charge with crocus and oil to finish. When the wheels are thin, it is better to rest them upon a large cork, cut flat and square, in the vice, and polish with a rubber, turning round the wheel slowly with the left hand.

Small brass wheels may be cut on an ordinary lathe, a good division plate with a good index peg being quite sufficiently accurate for wheels of, say, 3 or 3^ in. diameter. The cutter frame should be fitted with a single tooth fly cutter, for finishing. If the teeth are large, as for large turret clocks, previously remove the bulk of the material with an ordinary circular saw used in the cutter frame. For small teeth a fly cutter alone will do very well if sharp. Clock-wheel cutters drive their single tooth cutters at an enormous velocity, but where time is not a serious object a moderate velocity accomplishes the work as well.

Strictly speaking, every wheel ought to have a cutter adapted to its particular number of teeth, but practically there is so little difference in the shape of the spaces between the teeth of the large wheels that about four or five cutters are enough for anything from 12 teeth up to a wheel of 500 teeth, or a rack which may be looked upon as a wheel of an infinitely larger number of teeth. There is actually as much difference between the cutter for 12 teeth and that for 14 teeth as there is between the 100 and the 500, or rack cutter. A set of accurate template gauges, 10 in number, and 2 in. pitch, the first of them being for 12 teeth only; the second suitable for 13, 14 or 15; the sixth from 27 to 34; and the ninth from 7 5 to 300; the tenth for any greater number, will show that difference between the successive plates is very nearly even throughout the set.

To chuck a wheel ready for cutting : if it is a thick wheel or has a boss, it may be driven on to an arbor and held between the lathe centers; or if it has no boss, it may be put on to a spindle like that of a circular saw, with a flange and nut. If it is a wheel with arms or " crosses " like an ordinary clock wheel, it will want support sideways to stand against the cut. To secure this, face off a boxwood chuck whose diameter is a trifle less than that of the wheel to be cut, and drive into its centre a brass peg, which afterwards turn exactly to fit the hole in the wheel, and then fix the latter with some small clamps held by ordinary wood screws, which are screwed into holes in the face of the wooden chuck. The clamps may be made of any odd pieces of stout brass or iron plate that may come first to hand, their shape being of little or no consequence.

The shape of cutters to suit pinion-wire may be got by calculating the diameter of the conical grinders that are used for sharpening the quarter hollows of the single tooth cutters, working from a drawing done to a very large scale by simple rule-of-three sum.

All clock-wheels have their teeth points " rounded" to their proper shape when they are cut originally; but, in the event of one tooth having to be " topped," a file has to be used called a topping file, which is made with a flat-filing face, and a " rounded off" back ; that is, it should be curved and quite plain, so that the back of the file rubbing against a tooth while the point of the next is being re-shaped, no damage will occur. The same shaped files are used for forming pinion leaves. Clock-wheels are rigid, and supposing that they are mounted on their respective arbors and fixed in the lathe or "throw," and continuous motion produced, water of Ayr stone and also blue-stone referred to before may be used to advantage, but the fine finish has to be produced by means of "redstuff," probably by some workmen considered to be a crocus, though not really so. Tool-dealers sell it, and the kind necessary for the purpose is in lumps, in colour light claret, and mottled, resembling mildew. Such redstuff, mixed to the consistency of cream, is to be used after the dirt and grease have been removed with bread. Procure a piece of boxwood, 6 in. long, 1 in. broad, \ in. thick, file it very flat and smooth, then apply some of the mixed red stuff to the boxwood by dabbing it on for two inches or three inches in length with the end of clean finger; this polisher, pressed against and across the whole diameter of the wheel while in motion in the " throw," and drawn gradually backwards and forwards, will produce a flat and smooth surface, having circular lines. By cleaning off the dirty mixture with bread—having the bread quite clean, and mixed with a little very clean oil—a second application of the polisher will produce greater luster upon the wheel, and by successive polishings and cleanings a bright polish may be obtained. Don't use rouge with the mixture, because it soon dries and causes the polisher to adhere when it should be free, and for such work the burnisher must never be used. All that has been stated concerning cleanliness must be strictly adhered to be successful.

For American clocks the wheel is first stamped out in a circular form; then it is "gutted"—that is, the spaces are made between the arms or spokes; the blank is then passed through a machine which makes it perfectly flat, and it is sent to a machine where the teeth are cut. Fifty or sixty of these wheels are placed together upon a steel spindle and run under a small circular saw, which makes the teeth. The cutter makes the required number of slits or grooves upon the circumference of the brass wheels, and in two or three minutes the teeth are all made. These wheels are again run under another machine, which rounds the corners of the teeth and finishes them up. They are then polished, dipped in acid to brighten them, and then plunged in lacquer to keep them from tarnishing. It is a mistake to suppose that the teeth of these American wheels are stamped out; they are cut in the same manner as the teeth in English clock-wheels.

The first thing to be done before taking out the wearings, or altering the shape of the pallets, is to let down the temper of the steel. This is done by heating to a cherry red, and allowing the pallets to gradually cool again. Having thus softened them, file the wearings nearly out with a rather fine file, and bend to proper shape. Then smooth-file them, and lastly, with a bell-metal or soft steel rubber and oil-stone dust, finish the acting faces of the pallets very smooth and free from file marks. Then close the pallets by bending them till they closely embrace the number of teeth they originally did. This is done with the greatest safety by placing the pallets between the jaws of a bench-vice and closing the vice gently. It will be noticed that by this method of closing pallets, the part nearest the movable jaw of the vice will bend first; so, after closing them a little, it will be well to reverse the pallets in the vice that each arm may be closed equally. This method of bending is better than that of using a hammer; the strain does not come on the steel so suddenly, and pallets very seldom break when closed in this manner. After the pallets have been filed and closed, they are placed in the frames along with the escape wheel.

If, upon trial, there is found to be too much "drop" off the outside pallet on to the inside one, the pallets need " closing," or bringing closer together, which may be effected by placing them upon the jaws of the bench-vice, opened to a suitable distance, and giving them a tap with a small hammer, so as to bend them nearer together. Take great care in doing this, and see that the pallet arms have first been softened by heating as before directed, or they will break. If there is too much "drop" off the inside pallet on to the outside one, the pallets require bringing nearer the wheel. If the excess is not very great, it may be conveniently adjusted by lowering the bridge or cock a little. To do this, remove the steady pins from the cock, and move it down so that the "drop" is corrected; file the screw-holes in the cock upwards, then plug the old steady-pin holes, and drill new holes in the plate for the steady-pins, so that the cock will be kept in its new place. When the drop is very excessive, a new hole must be put in the front plate nearer to the escape wheel, and the cock lowered as much as is necessary to make the drop equal and correct. Fig. 48 shows the escape-wheel and pallets. The arrow indicates the direction in which the escape-wheel revolves; A is the outside pallet, B the inside pallet. The pallets can now be hardened by heating to cherry redness and plunging into cold water, and afterwards tempered by warming till a part, previously brightened with emery, turns to a straw color.

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Hasluck, Paul N. The Clock Jobber’s Handybook. London: Crosby Lockwood and Son, 1889.

This and the following pages are excerpts from the book.