Fig. 21.
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 admirably for this purpose. After you have carefully centered your wax chuck, place a small alcohol lamp under the chuck and heat it until the wax will just become fluid and yet not be hot enough to burn the wax. Revolve the lathe slowly and insert the staff so that the pivot rests squarely and firmly in the center. Now re-heat the chuck carefully in order that the wax may adhere firmly to the staff, keeping the lathe revolving meanwhile, but not so fast that the wax will be drawn from the center, and at the same time apply the forefinger to the end of the staff, as shown in [Fig. 18 and 19], and gently press it squarely into place in the wax chuck. The lines in [Fig. 18 and 19] designate about the right amount of wax after the work is ready, but it is well to add a little more than is shown in those figures, and you should be careful to keep the wax of equal bulk all around, or when it cools it will have a tendency to draw the staff to one side. Now remove the lamp and keep the lathe revolving until the wax is quite cool, when it should be removed, by means of a graver, down to the dimensions designated by the lines in [Fig. 18 and 19]. When this is accomplished re-heat a little, but only enough to make it soft, but not liquid, and placing a sharpened peg-wood on the tool rest proceed to the final truing up, by resting the pointed end against the hub.
CHAPTER VI.
I have described above one of the methods in vogue for holding a staff by means of wax. It is the common method employed by most watch repairers, the popular method so to speak. The method which I am now about to describe may seem awkward at first to those who have not practiced it, but once you have fairly tried it, you will never be contented to work in any other way.
The first requisite is a true taper chuck; and it is well to purchase an extra one to be used solely for this purpose, so that you will be prepared at all times for staff work. Select a good steel taper, and having placed your chuck in the lathe, see if your taper fits well by inserting it in the chuck while running slowly. If it fits well, it will be marked almost throughout its length. Insert again in the chuck, and with a few light taps of the hammer set it firmly in place, so that you know that there is no danger of its working loose. The taper will then project about three-quarters of an inch from the face of the chuck. By means of a sharp graver, make the face of the taper smooth and straight, and cut off the taper end. Now mark a point on the taper about one-fourth of an inch from the end, and proceed to turn down the diameter from this point to the end, leaving that portion of the taper about two-thirds of its original diameter, and finish with a nice square shoulder. Now with a long-pointed sharp graver proceed to cut a nice V-shaped center with an angle of about 60°. When you have proceeded thus far you will find that you have an implement resembling that shown in [Fig. 22].
