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Watchmakers' Hand Book

Part II,
MATERIALS EMPLOYED IN HOROLOGY
Page 14

SMOOTHING.

      170. If a surface is smoothed well, the labor of polishing will be diminished by at least one-half, and it is an essential preliminary if a good gilding on brass is required.

      The materials most frequently used are emery and oilstone dust for steel, pumice and water of Ayr stone for brass. The stones should not be traversed by veins, nor exhibit hard grains. Powders should be freed from large or hard grains by decantation, and it is advisable to repeat this operation several times in order to have several degrees of fineness.

SMOOTHING OF BRASS.

      171. Every watchmaker knows that after finishing the object with a smooth file, it is smoothed, first with a blue stone or rather coarse water of Ayr stone, and then with one of finer grain. If the brass is to be gilt, the operation is concluded with a series of circular strokes, so as not to leave any striae or bright spots; if the surface is to be spotted or watered the final strokes should all be parallel.

      A soft piece of charcoal applied with water may also be used on objects intended for gilding; in other cases it is used with oil.

      172. Wavy or watered smoothing. This is done with water of Ayr stone and oil carefully prepared, or with a piece of wood charged with oilstone dust, etc. The oiled corner of an emery buffstick can occasionally be used.

Part II Fig 41

      To obtain wavy undulations on a smooth piece of metal, the finger should first be placed at the point of commencement of the undulations. Resting the wood or stone against the finger, it is moved a little in a straight line, and then in a series of semi-circular waved lines, from right to left or left to right. The finger is advanced through a definite distance and the operation repeated, and so on.

      A very good watered surface can be produced with soft charcoal. With a view to increasing the regularity in the marks, a rule may be laid on the object, against which the charcoal is brought.

      Parallel watering is usually done mechanically, but any watchmaker can secure regularity by the following simple device.

      Fix a graduated rule t g across the cork (fig. 41) and two pins A A, to form stops for preventing the stick or stone from traveling too far. A division of the rule is made to correspond with the line v v; and, when the first line has been traced, advance the object by one, two or three graduations of t g, according to the interval that is to be left between successive undulations. Then trace the second wave, and so on.

      173. Wavy and curvilinear smoothing. These are of two kinds; some are entire circles, which we shall proceed to consider; others radiate in curves from the circumference to some other point of the circle as, for example, many of those that are met with on keyless ratchet wheels. The latter will be discussed farther on, when discussing the smoothing of steel, for the process is identical for both steel and brass, except that with the latter named metal and nickel the stick may be replaced by a strip of zinc or tin, and coarse rouge is used.

      174. Circular snailing or spotting. This is produced on a special tool by which several motions can be given to the object, but watchmakers as a rule, so seldom have occasion to trace this class of ornament, that it will suffice to explain how it can be produced by the appliances that everyone has at hand.

Part I Fig 42

      The universal mandrel may be employed for the purpose, but, in that case, the operation is a very slow one, whereas, with the ordinary lathe, it can be done both rapidly and well.

      Adjust a rest of the form shown at s (fig. 42), taking care that the height of the center is sufficient; the small rectangular bed a a has a projecting edge, divided by equidistant graduations. To the headstock of the lathe is attached, at b, a piece of bluestone or wood. Having set the rest at a convenient height, and holding the object to be spotted, P, on the rest, bring it in contact with b when in rotation. When the mark is made, lean the object from b, slide it along a a so that its edge coincides with the next division and make another mark, and so on until an entire row is completed. Then raise or lower the rest and repeat the process for a second row, and so on.

      Instead of applying oil to the acting face of b, which would have to be renewed at each operation, it is usual to cover the object P with oil, if b is a stone, or with oil mixed with the substance used for smoothing, if b is of wood. It this precaution is taken, the work will progress much more rapidly.

      When the object operated upon is of irregular shape it must first be attached to a rectangular plate and then proceed as already stated.

      A still more simple method, but one that is, in certain cases quite sufficient, consists in passing through the poppet-head a center of the form f d (H, fig. 42) which is caused to rotate by the fingers or any other means.

Part II Fig 43

      To make spottings that, instead of being parallel, radiate from the centre to the circumference, the rest a a must carry a disc that can rotate on a clamping screw, and is maintained in position by a finger, with an even number of equidistant divisions on the circumference of the disc. The object to be operated upon is then fixed to the disc, and a stick used, the diameter of which is equal to the distance between two radii that pass through a pair of graduations on the disc; for example, the small circle s (fig. 43). A series of circular spots is then made by gradually rotating the disc. Now replace the rod s by one of the diameter n; advance the support until it corresponds with the position n, and make the second range of circular spots, and so on. The figure renders any further explanation necessary.

      The watchmaker who has clearly followed what precedes will be able, should occasion require it, to construct a special tool acting with certainty; but it will be well to remember that there is a great advantage in driving the spotting stick by the foot, and bringing it down on the object by a small hand lever, after the manner of the drilling machines used in factories.

SMOOTHING OF STEEL.

      175. The smoothing of a steel object is commonly done on a piece of cork, with a large iron polisher charged with oilstone dust and oil. If a flat surface, it can be finished with a copper polisher or on a sheet of glass. In the case of staffs, arbors, etc., that are not intended to be polished subsequently, a certain degree of brilliancy is given to the surface by rubbing with wood, usually peg-wood, or with a stick covered with the finest emery paper and oil.

      A surface that will not be subjected to friction--as, for example, the head of a screw--can be smoothed rapidly and well with a dry emery buffstick if little metal has to be removed, and the polishing can then be at once proceeded with. Only one cleaning is in this case necessary, for after the emery it will suffice to rub with pith and pass a brush over the surface.

      For ordinary work, smoothing a staff or head of a screw with dry, fine emery and finishing by the friction of rather hard pith backwards and forwards, will give a fairly satisfactory surface.

      176. White and dead smoothing. To produce a graining, the piece of steel must be previously smoothed in the ordinary way, perfectly flat and free from scratches. The graining is produced by rubbing the object on a sheet of ground glass with the finger, taking very small circular strokes, especially towards the end of the operation. The degree of success depends on the quality of the oilstone-dust employed. It must be very fine, and it will be a prudent precaution to decant the powder in water, or preferably in oil, and not to use the earlier deposits (168).

      When the oilstone dust is not very good, it may be washed in hydrochloric acid, which dissolves most of the hard grains, but it will require to be thoroughly washed in water afterwards, on account of the difficulty there is in removing the last traces of the acid. Of course such a method is only to be resorted to on an emergency.

      Perhaps the most difficult piece to grain is a keyless barrel ratchet, because if the operation is at all prolonged the edge of the ratchet may become white before the center and it may even polish. If this happens, the ratchet should be held in the hand and rubbed with a piece of pith cut to a blunt point with a flat end. By this means it is easy to act on the center, avoiding the edges.

      177. Dead white or frosted surface. After having grained the steel in the manner above indicated, if it is required to obtain a dead white frosted surface, employ a mud formed of Arkansas stone dust, or the sticky deposit on a whetstone, which is more easily obtained. It should not be too yellow, as the result is all the better according as a greater number of steel particles are mixed with the oil; at least, so we are informed by some very good workmen. A large piece of elder-pith having been divided into two equal parts lengthwise, is smoothed with a new, clean file; the mud is spread upon it, and the piece of steel is moved over it with circular strokes as in producing the graining. In this case the movement can be rapid. If the operation be well done, and if the oilstone dust used be of good quality, the object will, after being cleaned, present a beautiful uniform white surface in which the graining is still visible. Experience and knack are everything in the proper conduct of such an operation, especially in its concluding stage.

      The surface may be cleaned in pure benzine mixed with a little sulfuric acid, followed by a very clean buffstick, which will impart a brilliancy to the metal.

      M. Bean recommends fine Turkey oilstone powder mixed with turpentine as the best preparation for rapidly producing a dead smooth surface on steel-work.

      Workmen that are constantly engaged in graining employ a foot-wheel for the purpose. The ground glass is fixed so that, although not rotating, a small circular motion is communicated to it. The steel is then simply held against it; indeed, several pieces can be grained in this manner at once.

      To the methods above described we would add the following, which is successfully practiced by several English workmen:

      They lightly fix the ratchet, for example, by its edge, and finish the smoothing with a piece of pith, more or less charged with pure charcoal powder and fine oilstone dust. Here also knack is mainly instrumental in insuring success.

      178. Snailing. To produce the snailing on a fusee or on keyless wheel-work, the device shown in fig. 44 can be used. The ratchet or fusee is mounted between one pair of centers and driven by a cord from a foot or hand-wheel. The copper or iron lap, having a diameter equal to about three times that of the surface to be snailed, is charged with fine emery powder and oil, or oilstone dust, etc., and set in contact with the face of the steel, which thus causes it also to rotate. The direction of the snailing will be the same, whether the rotation is to the right or left. If it be required to change the direction, the relative positions of the two pieces must be reversed.

Part II Fig 44

      It has been already observed that brass and nickel can be snailed in the same way, employing a zinc or tin lap and coarse rouge (173). In some cases, hard wood laps can be used for these softer metals.

      In keyless steel wheels a beautiful snailing can be obtained with Arkansas stone mud (or, in its absence, the greasy mass from an oilstone) mixed with polishing rouge.

      With reference to the little tool shown in fig. 44, it may be observed that, if the axes of both the steel piece and lap were driven by bow or otherwise, the surface would be polished and not snailed.

      In the absence of the tool here referred to, any one can easily construct one for the purpose which will adapt to the mandrel of a foot-lathe: in order to help him in doing so we will describe one designed by M. Cadot, of Paris.

Part II Fig 45

      179. Tool for snailing. This is shown in fig. 45, and we would at the outset observe that it can be used equally well for polishing. To a shoulder at the extremity, A, of a piece of steel rod, B (which takes the place of the slide-rest cutter) is riveted an L-shaped piece c c d, and to the point d is firmly fixed by a screw or rivet, the upright piece d h parallel to c c; this piece is enlarged at h so as to give a bearing to a hardened steel screw, with a hollow point, in the axis of B: the lap is supported between this screw and a hole in the center of A. The figure will suffice to indicate the form of this lap which is dished internally as shown by the dotted line. It is made of iron or copper if intended for use with hardened steel.

      The piece to be snailed is fixed to a chuck of the foot-lathe, and, having fixed the rod B in place of the cutter, the lap is brought, by means of the slide-rest screws, in contact with the steel, taking care not to set it up to the center, as snailing that starts from the center is not so good. Having charged the lap with fine emery and oil, the object is rotated and it sets the lap also in motion.

      It was mentioned above that this tool can be employed for polishing: for such a purpose use fine rouge, replace the lap by one of bronze or bell metal, fix a ferrule at i, and, while the object turns in the lathe, rotate the lap with a bow.

      By fixing a rod at I, instead of at B, the tool is at once adapted to be used in an ordinary pair of turns, as it can be fixed in place of the T-rest; but it is not so easy to secure parallelism of the two surfaces.

Part II Fig 46

      180. To restore the watered surface in nickel movements, etc. Although the following is employed for nickel (or rather German silver) it may be well to observe that it is equally applicable to all other metals.

      As these nickel movements are not gilt subsequent to being repaired, it frequently happens that the water marks on the surfaces do not correspond. By the aid of the following device watchmakers can correct this fault, but we must warn them that, as in all operations involving dexterity, they must first make experiments in order to acquire the requisite manual skill.

      On a small open frame C C, fig. 46, fix several parallel bars f l, e d, etc., and on two of these adjust a slide p o n m, with two strips glued underneath so that it can travel up and down between a and b. On p o n m, fix a guide of convenient form, as G: and, after cementing the piece, say A, that is to be watered on a board resting on the bench, place the frame C C above it and trace the figure of the guide with a pegwood stick charged with polishing material. The same figure can be reproduced in parallel rows as the guide can be moved up or down.

      By varying the shape and position of the guides, the water lines can take the form of waves, festoons, circles or ovals. In the two latter cases the guide has apertures of the requisite form. and the board that carries A, not being more than half the size of the aperture, can be moved about by hand or by a tool.

      If preferred, one of the bars, as e d, can be graduated and arrangements can be made for clamping the slide by screws in any position.

      These explanations will suffice to enable any intelligent watchmaker, after a few trials, to imitate successfully any of the beautiful watered surfaces that are, on a manufacturing scale, produced by machinery.

      As regards the material to be used, first mix medium rouge and putty powder in equal proportions. It will be possible to decide from the shade obtained whether more putty powder should be added, because when there is too much rouge, the surface does not acquire a good white color.

Submitted by: Samuel Kirk (##)

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