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Materials Used In Construction And Repair Of Watches

( Originally Published 1918 )


STEEL is used for all the hard-wearing parts of watches, and for parts where strength and rigidity are required—winding squares, barrel arbors, pinions, balance staffs, levers, keyless winding wheels, clicks, and for all screws. It is also used for mainsprings, hairsprings, clicksprings, and innumerable other small springs found in the various parts of keyless and other watches.

The steel used in watches must be of a high quality, and watchmakers generally obtain it in 12-inch lengths from the firms who especially lay themselves out to supply their wants of all kinds. This steel is obtained in the form of wire, rod, flat strips, or sheet. The wire and rod can be had in any size, from that required for the smallest balance staff to about 1/4 in. in diameter, from which a large barrel arbor can be made. The flat strips and square rods are used for making levers, keyless work, small springs, etc. Steel drawn in lengths of a special section can also be obtained for making particular parts, such as "hooking-in" steel for making blocks for hooking mainsprings, "click-steel" for making fusee winding clicks, "pinion-wire" for making pinions, "lever-steel" for making levers, etc. A specially hard steel, "silver-steel," can also be obtained. It is used by some watchmakers to make turning cutters, drills, etc.

Softening Steel.—Steel as bought is "soft," but, being drawn or rolled, is not so soft as it can be made, or as it is desirable to make it for some purposes. In the making of a screw, for instance, it is desirable that the steel be first made as soft as possible, so as to take a good "thread," and not injure the screw plate. To soften it, it is heated to a full red and allowed to cool slowly ; or it can be made a little softer still by heating to a red, allowing it to cool slowly until, when held in the shade, the red has completely disappeared, and then dipping it in water. This process is called annealing.

Hardening Steel.—In this soft condition it is shaped up by filing, turning, bending, etc., roughly to the required form and size. Before it can be used as a going part of a watch it must be hardened. This is done by heating to a full red and plunging into cold water or oil. Many special mixtures for hardening steel are used by some; also plunging into lead, mercury, etc., is sometimes advocated when great hardness is desired; but there does not appear to be any necessity for the use of any-thing else but water o1 oil. When steel is heated to a dull red and hardened in oil, it is tougher, though not so glass-hard as when made hotter and plunged into cold water.

Each method has its uses. For a spring, where toughness and elasticity are required, oil-hardening is best; while for a pinion or for a cutting tool, where extreme hardness of surface is wanted to resist wear and tear, water-hardening should be practised.

Tempering Steel.—Steel just hardened, even by the oil method, is far too brittle for most purposes, and it requires tempering. The application of heat tempers it, that is, it reduces its hardness somewhat, but gives less brittleness and more elasticity. This is only true up to a certain point, at about 57o Fahr. it reaches its maximum elasticity; when heated beyond this point, it rapidly loses both hardness and elasticity, until at about 1200 degrees (dull red heat) it becomes quite soft again.

As bright steel is gradually heated the surface becomes first of a pale straw colour; this deepens into a pale brown, turns to a red, purple, dark blue, pale blue, and then white again. These colours are extremely useful, as showing the temperature, and consequently the temper, to which the steel has been drawn.

Thus, to temper a piece of steel, it is first brightened, to show the colours well, then heated gradually over a spirit lamp flame or upon a slip of brass held in the flame. Blue, that is, the first dark blue that succeeds the red, is the temper to which ail springs, screws, pinions, keyless wheels, and other working parts of watches are brought to. The moment this colour appears the steel is removed from the flame, or the blueing slip, and allowed to cool. If a pinion or other part is required to be specially hard, it may be tempered to a red or a purple only.

A drill or a cutter for use on brass or soft steel only is tempered to a pale straw colour; but those for use on tempered steel are made as hard as possible, and not tempered at all.

Good steel may be many times rehardened and softened again without spoiling it, provided it is never overheated. A full red is quite hot enough for all purposes, and, small parts especially, should not be allowed to remain red long.

When hardening extremely fine pieces of steel, such as the drills used for making fine pivot holes, water or oil for dipping need not be used. Indeed, it would be quite impossible to use them, for the steel would be cold before it could touch the liquid. In such a case air-hardening is employed. The drill is heated in the flame, and, when red, withdrawn with a sudden jerk, and the air cools and hardens it. This is termed "flirting." Similarly, it is nearly impossible to soften such a drill or any other piece of fine steel. It could not be cooled slowly enough to prevent rehardening, mere removal from the flame being quite sufficient to harden it again. If such a piece is required to be softened, it must be laid upon a slip of brass upon which is also laid a small piece of brightened steel to indicate the colour. It is then heated, while the piece of " index" steel passes through the series of colours from straw to blue and on to white again. It will then be soft enough to be operated upon or bent as desired.


Brass is an alloy of copper and zinc, a common proportion for good quality brass being two of copper to one of zinc. Common cheap brass has less copper, and is not so strong or so hard. It is distinguished by its very white appearance when broken or filed.

Brass is used very largely in watches. The plates and framework, the wheels, and many other parts being in most watches made of it. Like steel, brass is capable of being softened, hardened, and, to some extent, tempered. Brass rods of all diameters and brass sheet can be obtained ready for the watchmaker. Brass rods, being drawn, are rather hard, but for ordinary purposes of filing and turning, etc., this condition is to be preferred, as it works cleaner than when quite soft. But if it is required to bend or hammer the brass out, it should be softened first.

Softening Brass.—This is done by heating it nearly to a dull red, and allowing it to cool, or, if time is an object, it may be cooled by plunging in water. The result is the same in either case.

Hardening Brass.—Brass is hardened by compression. Any process that tends to compress its particles against one another will harden it. Hammer hardening consists of hammering it with a smooth-faced hammer all over equally until it is sufficiently hard. Unskilful hammering, if long continued, is very liable to crack the metal. Drawing brass wire through a draw plate, decreasing its diameter, will harden it. Twisting a rod also has the same effect. Rolling, as in reducing the thickness of a plate or rod, will harden it. It must not be supposed that any hardening process applied to brass will render it as hard as steel, even in its soft state. But brass can be stiffened very much, and made so elastic that very serviceable springs may be made of it. It is often used for some of the smaller springs in watches.

Very thin brass can be conveniently hardened by simply burnishing it with a polished steel burnisher.

Tempering Brass.—If hammered too brittle, brass can be tempered and made of a more even hardness throughout by warming it, as in tempering steel ; but the heat must not be nearly so great. Brass, heated to the blue heat of steel, is almost soft again.

Gold is a useful metal in watches, for small special parts. Hard, polished and burnished gold, when working in connection with hardened steel or jewels, causes very little friction indeed. It seems to take a very slippery surface, which is useful in certain cases. Its incorrodibility is also a recommendation. It has been used for hairsprings, but for this purpose its weight is against it. For the screws used to weight compensation balances, for small contact pieces such as curb pins, etc., it is invaluable. Its weight makes it useful for balances, and its extreme ductility is useful in the collets of small wheels, etc., where a good rivet can be formed upon it without undue pressure. As a protective covering for brass, in the form of electro-gilding, it is used in nearly all watches. Also for dial plates and for hands it is much used.

Gold is hardened, tempered, and softened in the same way as brass, but is capable of much more in the way of hammering than that metal, being more ductile.


Silver is not nearly such a useful metal for watchwork as gold. Not being easily corroded, it is used for small engraved index plates for regulators, and sometimes for dial plates.

It is worked in the same way as gold. Both gold and silver, being very ductile, can be readily worked up for use in watches. Almost any scrap of metal, such as a jump ring, or a broken brooch pin, can be softened, straightened out, hammered flat, or drawn into convenient sized wire with ease, and serves to make such small articles as screws, pins, or small springs as are required in watches of these metals.


This metal is really a kind of white brass. It is an alloy of copper, nickel, and zinc, in which copper is the predominating metal. It is used in watchwork mainly for the frames and plates of so-called " nickel" movements, of which so many are made in America and in Switzerland. It is worked exactly as brass, but is a little harder than that metal. It is white, and takes a good polish. Movements made of it are not gilt to preserve their surface, but are generally ornamented by "spotting" or etching patterns upon them. They do not readily tarnish.


This metal is only used in watches for balance screws. Here its weight is sometimes an advantage, and often enables a watchmaker to overcome difficulties in timing a watch. It is a very soft metal, and screws made of it are easily damaged by handling.


The only use to which this metal is put in watches is for balances and balance springs for non-magnetic watches, where it takes the place of steel. It is not used pure, but is alloyed with other metals to harden it. Even so, it is but an indifferent substitute for steel, balances made of it being soft and easily put out of truth, and balance springs made of it are heavy and soft, easily distorted and damaged, and unsteady in pocket wear. Still, as it answers the purpose of making the watch incapable of being magnetized in its most vital parts, it is used in spite of its softness. In marine chronometers it is often used for the balance springs, and, it is claimed, has advantages in enabling a more perfect adjustment to be obtained. Here, on account of the thickness of the spring wire, its softness does not matter so much.


This is an alloy of aluminium and copper, in which the copper largely predominates. It is hard, takes a high polish, and has a beautiful golden colour. It is a hard-wearing alloy, and is very light. It is largely used for the train wheels of watches, more especially Swiss and American, and for levers and scape wheels, where its wear-resisting qualities and its lightness render it extremely useful. It can be worked much as brass as regards hardening, etc.


Invar is a nickel-steel alloy having the peculiar property of hardly expanding or contracting at all with changes of temperature. For this reason it is used for clock pendulum rods and in watches has been used in the construction of compensation balances. It resembles steel in colour and hardness but is rather tougher, and difficult to drill, file, or turn, on that account.


Rouge, red-stuff; and crocus are all one and the same thing, but differ in fineness in the order named, rouge being the finest and the slowest in cutting. They are metallic oxides, and are fine red powders used for polishing metals. The most generally useful in watchwork is the grade known as fine red-stuff,, in lumps that are easily pounded up into a paste with oil upon a polishing stake. This should be a dark purple-red in colour.


This is a polishing powder much used by some, and for some purposes to be preferred to red-stuff. It is white, and sold in small bottles. It has nothing to do with diamond powder, but is only a fancy name given by its makers.


As its name indicates, is the fine dust produced by crushing diamonds. It is not used in watchwork for polishing metals, but only for the materials so hard that no other polishing powder will cut, such as ruby pallet stones, jewel holes, ruby pins, etc. Used on an iron lap wheel, it is very useful for just trimming the corner off a pallet stone and similar purposes. Though used largely by watch jewellers in the manufacture of jewel holes and ruby pallets, etc., the repairer does not need much of it, except as stated above.


This is oilstone reduced to powder, and is useful made into a paste with oil, for smoothing steelwork preparatory to polishing. It leaves a fine, even, grey surface. It can be also used for " spotting " and " snailing."


Emery, in the form of emery sticks, is very useful. The usual kind of emery stick used by watchmakers is made by glueing fine emery paper upon wood. These soon cut through, but, being very cheap, this does not much matter. Their flatness and general handiness outweigh any disadvantages they may possess. They are obtainable in various degrees of fineness, from the finest, No. (4/0, to about a No. 4. The coarser ones will rapidly cut a brass plate and keep it fairly flat. They will also cut steel that is too hard to file. The finest produce a passable substitute for a polish upon both brass and steel, especially when they have worn fairly smooth and got the new " cut " taken off them.


This is a mottled, slaty-coloured stone, used in a block with- water for stoning brasswork smooth for gilding or for polishing. A slate pencil, flat on the end, can also be used for the same purpose, and in a confined space has advantages.


Prepared chalk is used dry on watch brushes for cleaning watches and to keep the brush clean. Billiard chalks are a very convenient form in which to buy and use it.


For cleaning the old oil and dirt from watches and for cleaning off various polishing pastes from parts, etc., benzine is used. It is kept in a glass pot with a ground-in glass cover to prevent evaporation, the vapour being highly inflammable. It can generally be purchased at a chemist's.


Petrol, as used for motor-cars, can be used instead of benzine for cleaning watches. It evaporates quickly and leaves no stain, being fully equal to the best benzine and far cheaper. Like benzine, it is highly inflammable.


The oil used for watches is best bought in small bottles, specially prepared by makers of good repute. Attempts to refine oil for watchwork generally end in failure, and experiments in this direction are too dangerous. That prepared for French clocks is useful for mixing the polishing pastes with, for lubricating drills and such purposes, being a pure and rather thin oil. It is also useful for the heavier parts of watches, such as main-springs and barrel arbors, etc. For train-wheel pivots and escapements, only the best watch oil should be used,


This is used for the watchmaker's lamp. It burns with a clean, smokeless flame. Articles heated in a spirit-lamp flame are not made dirty and blacked. Spirit is also used to dissolve shellac. When an article has been cemented with shellao for turning, the shellac is removed by boiling in a little spirit in a spoon.


For lubricating hard steel drills, when drilling glass or tempered steel, turps can be used with advantage; also for lubricating a file used upon glass, or on an enamelled watch dial. It cuts more quickly, and lessens the chance of chipping the edges.


Of the acids, probably the only one useful in watchwork is hydrochloric acid or spirits of salt. It does not act quickly upon brass, but dissolves steel. It is used principally to remove blue oxide from steel by dipping. It is' also useful in making soldering fluid. Needless to say, it should be kept far away from the watch board.


This metal is mentioned, not that it has any use in watches, but that it is a metal that often finds its way into watchmakers' workshops in the form of beads from a broken barometer or thermometer. When it does so, it is extremely difficult to get rid of. It will find its way on to gilt watch plates in an astonishing way, and spoil them by amalgamating with the gilding and spreading all over them. Therefore keep mercury far away from the workshop. It is true it was used in some marine chronometer compensation balances by Loseby, but they are not likely to get into the hands of watch repairers. It may therefore be said to have no use in watchwork. Mercury can only be removed from a watch plate or case by heating over a spirit lamp and evaporating it. The parts then will require polishing again or gilding, as the case may be.


Sticks of dogwood, known as "pegwood," are used for cleaning out the pivot holes of watches and for various small operations. They are bought in bundles ready for use.


Elder pith, well dried, is useful for cleaning pivots and other parts. It can be obtained by peeling the sticks themselves and drying, or it may be bought in bundles ready for use.


The tissue paper used for holding parts of watches while cleaning, and for wrapping up movements, etc., should be sun-bleached. Such paper is known as silver-paper, and does not tarnish metals like the common sulphur-bleached paper.


For cementing pallet stones, ruby pins, etc., in their places, shellac is used. Shellac is a gum, which, when cold, is brittle and hard. It can be melted by gentle heat, at about the heat of boiling water; or it can be dissolved in spirit of wine to remove it. It is conveniently purchased in flakes.

All the materials mentioned in this chapter, and all tools and watch parts mentioned in this book, can be bought from watch material dealers, of whom there are many in Clerkenwell, Coventry, Birmingham, and other large centres.

Watchmakers of today find it hard to realize the difficulties under which their predecessors worked. To go no further back than a century, the assortment of tools which they could purchase was very limited. Watch materials were more limited still. They had to make nearly all their small tools, and if a new part were required in a watch, they had to make it outright from the rough brass or steel. Now we buy drills in sets numbered in tenths of a millimetre, broaches, files, and punches in assorted sizes and of every imaginable form. If we require a wheel, a pinion, or a cylinder, we have only to write for it, and obtain it for a few pence with all the difficult work done.

But if the modern watchmaker is spared much of this work, it is well to remember that the great variety of watch movements and the quantity of cheap rubbish now met with, possessing every fault that such things can have, renders the task of repairing watches and keeping them in good order as difficult, and perhaps more difficult, than ever. The introduction of machinery into watchmaking has resulted in the production of watches having some parts that, while turned out by a special machine for less than one penny, will take a good workman the best part of a day to make by hand. In such cases it is well indeed that duplicate parts can be bought, or these watches would not be worth repairing at all.

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