In chapter IV I called attention to the right and wrong way of holding the graver while using the extreme point, and also the correct manner of applying the graver in turning conical pivots. I also called attention to the fact that it was well to only use the point of the graver where positively necessary, as in the back slope of the pivot, etc. In turning the seat for the balance, as indicated at A, Fig. 15, the graver A, Fig. 1, or a similar one as shown at B, Fig. 15, should be used. The slope at C should now be turned. In turning the pivot and seat for the roller, you should leave them slightly larger than required, to allow for the grinding and polishing which is to follow. No definite amount can be left for this purpose, because the amount left for polishing depends entirely on how smoothly your turning has been done. If it has been done indifferently, you may have to allow considerable for grinding and polishing before all For grinding, bell-metal or soft iron slips are desirable, and the grinding is effected by means of oil stone powder and oil. Two slips of metal similar in shape to A and B, Fig. 16, are easily made, and will be found very useful. A is for square pivots, etc., while B is used for conical pivots. These slips should be dressed with a dead smooth file, the filing to be done crosswise, to hold the oil stone powder and oil. During the operation of grinding, the lathe should be run at a high speed and the slips applied to the work lightly, squarely and carefully. The polishing is effected by means of diamantine and alcohol. After the work is brought to a smooth gray surface, slips of boxwood of the shape shown in Fig. 16 should be substituted for the metal slips. Oil stone slips are sometimes used in lieu of metal ones, but they soon get out of shape and are troublesome to care for on this account. All things considered, there is nothing better for polishing than a slip or file made of agate, say one inch long, one-quarter inch wide and one-eighth inch thick. A slip of this kind can be obtained from any lapidary, and after grinding with emery and water until the surface has a very fine grain, it should be mounted by fastening with cement into a When the staff is finished from the lower pivot to the seat of the balance, the upper part should be roughed out nearly to size and then cut off preparatory to finishing the top part. Attention was previously called to the fact that the majority of watchmakers prefer to finish all the lower portion of the staff first, notwithstanding the fact that there are numerous advantages to be gained by proceeding to first finish up the upper portion. We have now reached the point where the wax chuck must be used, and perhaps these advantages may be now more clearly defined. In order that the two procedures may be more Before proceeding to set the staff in the wax, it is necessary to make some measurements to determine its full length. Remove both cap jewels and screw the balance cock in place. Examine the cock and see if it has at any time been bent up or down or punched to raise or lower it. If so, rectify the error by straightening it and then put it in place. Now with a degree gauge, or calipers, proceed to take the distance between the outer surfaces of the hole jewels and shorten the staff to the required A very handy tool for the purpose of making these length measurements can be constructed by adding a stop screw to the common double calipers as shown in Fig. 20 . The improvement consists in the fact that they can be opened to remove from the work and closed again at exactly the same place, so that an accurate measurement can be made. The all-important point in the use of wax chucks is to get a perfect center. If you are not careful you are liable to leave a small projection in the center as shown at A, Fig. 21. The ordinary wax chuck cannot be unscrewed from the spindle and restored to its proper place again with anything like a certainty of its being exactly true, and if you insist on doing this there is no remedy left but finding a new center each time. It will be found more satisfactory and economical in the long run to have a permanent chuck for a wax chuck and you will then have no necessity for removing the brass chuck. The center, or cone for the reception of the pivot, should be turned out with the graver at an angle of about 60° and such a graver as is shown at B, Fig. 1, will answer |