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Watch Repair - Cases

( Originally Published 1918 )



WATCH cases may be made of gold, silver, German silver, brass, or oxidized steel. Gold keeps the cleanest and, on the whole, wears best. But the material of the case is not of much importance as regards the timekeeping of the watch. The essential is that the case must be sound enough to resist outside pressure, and the covers and bezel must snap tight and fit well. Dust and dirt will find their way through an astonishingly small space, and very accurate fitting is required to keep a watch clean if the wearer is engaged in a dusty business. The various parts of a case are : (Fig. 166) A, the " band," or middle, B, the " dome," C, the " bottom," D, the bezel " that holds the glass, E, the "pendant," F, the "bow." A hunting or demi-hunting case also has a " cover" over the glass.

In many full-plate English watches the dome is a fixture and does not open. In other watches the dome is absent altogether ; such cases are called " single bottom" cases, and are not to be recommended for wear. Bottoms and bezels are sometimes jointed to the case band and sometimes are loose, being merely snapped on tight. These circular snaps, as they are called, are much more dust tight than a joint can be. Some bottoms have fly-up springs and a lock spring, and are opened by pressing a "push piece" in the case pendant. These are convenient, but let the dirt in very much. After a little wear there is seldom any fit at all. Dirt also reaches the watch through the holes made for the push piece and the fly springs.

Many modern American watch cases have the bezel and bottom screwed on by a fine thread cut in a lathe. This is, perhaps, the best possible way of making a case. The edges of these are generally slightly milled to give a hold to the fingers in unscrewing them.

The Americans also bave introduced the practice of making "gold filled" cases. In the making of these a plate of brass is sandwiched between two thin plates of gold and all brazed together. This plate is then rolled into sheet, pressed into shape, and finally worked up into the various parts of a watch' case. The result is a case the bulk of which is brass, but which has all its surfaces, outside and inside, covered with a thin but sound layer of gold. These cases wear many years.

Snaps.—With wear the snaps of a case are apt to loosen. To tighten them, burnish the edge of the bezel or bottom inwards with a wetted oval burnisher and heavy pressure, as in Fig. z 67. Or the snap on the case band, in the case of a bezel, can be burnished outwards, as in Fig. z68. A snap that is too tight can be eased by scraping the edge off the snap a little all round with a sharp square-edged steel scraper and afterwards burnishing smooth.

Glasses.—Bruises in a bezel on the edges of the glass groove can be pushed out from inside the groove with a watch screwdriver, and afterwards cut smooth inside by a graver point. A very badly bruised and damaged groove must be re-turned by a case-maker before it will hold a glass again.

Fig. 169 shows sections of the various kinds of glasses in use. A is a common " lunette," B a "double lunette," C a common "crystal," and D a " flat crystal." E is an old-fashioned " bull's eye " glass, and F a " patent hollow crystal."

Glasses are sized in a series of numbers subdivided into quarters and eighths. These numbers are based on the Paris "line" and the " millimetre." Lunette and double lunette glasses are generally sized in quarters ; crystals and thin flat lunettes for hunters in eighths. Hunter glasses are also sized in " heights " as well ; thus a 16* size may be had in 5, 6, q, or 8 height. Each make of glass seems to differ a little, therefore it is best to stock one make only throughout, and fill up with the same to keep a good running series for fitting.

There is a knack in snapping in a good-fitting glass, only acquired by long practice. Never try to fit a glass with the bezel closed. A glass a trifle too loose may be fixed by running a drop of gum round the groove with a peg point, and turning the glass round to work it in; then leave an hour to dry. Do not attempt to tighten a glass by burnishing the groove, as the bezel will be ruined thereby. Similarly, do not try to cut a bezel groove out deeper to take a glass that will not quite go in. Instead, trim the edge of the glass with a No. 0 emery buff by hand, working gently round and round to keep it even ; smooth off with a 3/0 to finish.

Bruises.—A bruise in a dome or bottom may be knocked out by resting the inside on a boxwood case stake, like Fig. 170, and using a wood mallet. To prevent marking, cover the stake with tissue paper. Badly scratched cases are smoothed with rottenstone and oil on a leather buff or rag mop in a lathe, and polished with rouge and water on a mop, or by rouge on the hand. Bruises in the case band can be pushed or burnished out from inside and the remains smoothed off outside by filing, followed by smoothing with rottenstone and polishing with rouge.

Joints, etc.—The joints of cases are fitted with steel joint pins sunk in at each end. The end spaces are then filled in with silver or gold plugs and smoothed off neatly. To take off a jointed bezel or bottom, the silver or gold plugs can be picked or drawn out by inserting a graver point into them deeply and drawing them, as in Fig. 171. The steel joint pin can then be driven out. A joint that is "sprung," and will not allow the case to shut, can sometimes be sprung back by laying a thin wire along it inside and shutting.

Fly springs and lock springs are filed up from turned rings of steel, hardened and tempered. They are difficult to make, and, like new joints, are best left to case-makers.

A new push piece is a common repair. Push pieces are bought in the rough with a small piece of gold or silver soldered an the end. Hold by the thin end in a pin vice and reduce the head by filing until it passes into the pendant. Then reduce the thin end until it will go down and push the lock spring. Reduce it in length, and file out the hole through which the bow screw passes.

Bows.—Bow screws are always breaking or wearing out. . They are bought by the gross and are easily fitted. Sometimes there is difficulty in getting the old one out. If anything at all projects, cutting nippers will generally turn the stump out. If nothing projects and it is tight, it must be drilled through. Pass the drill through the other hole in the bow as a guide to keep it straight. When drilled through (with a small drill), broach it out, and it will finally come out on the broach as a thin tube.

The bow of a keyless watch requires pivoting in carefully, as in Fig. 172. A special tool is made for this purpose, but the operation can be done very passably by hand with a file, resting the bow on the filing block.

A case pendant in which the bow holes have worn very large requires plugging and soldering up by a casemaker, to make a good job, but a makeshift may be made by turning two washers or flanges to fit on the bow ends and lie in the worn hollows in the pendant.

The bow of a keyless watch can be sprung on or off by a pair of round-nosed pliers, as in Fig. 173, by screwing one side of the pliers in the vice and using the ends as a lever to open the bow.

Silver and gold are very soft metals, and burr when drilled. Therefore, in making a new keyhole in a case, use a very sharp drill and make only a small hole. Enlarge this by filing with a new sharp file, drawing it as required. Chamfer off the sharp edges with a rose cutter or a circular chamfering tool.

The dome and bottom often cause a watch to stop by pressing on the set-hand square, the fusee winding square, or the balance-cock jewelling. In these cases it is best to shorten the squares to free the case. But if it touches the balance jewel-ling the dome must be raised. Evidence of such contact is generally seen in the impression of the jewel screws or jewelling in the dome. Raise it by hammering with a mallet over a stake as in taking bruises out. When the dome has been raised it is generally necessary to raise the bottom also to free the dome.

The cover of a hunting watch is made to fly up by the push piece and fly springs. Sometimes the joint is stiff, preventing the cover from flying up properly. Run a little oil into the joint and work the cover vigorously for about five minutes. This generally effects a cure.

Cases with monograms, if not under 3 douzièmes thick, can have them erased by filing (save the filings) and re-polished. If not thick enough for this, a case-maker can fill the letters in by running gold into them and smoothing off. Worn engine turned cases can be polished plain or re-engine-turned. A full hunter may be cut and enamelled as a demi-hunter. But at lunette bezel cannot be respectably made into a crystal. The case is always a bad shape afterwards.



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