A Treatise on Staff Making and Pivoting | Page 2

workmanlike manner, is never certain of having exactly what is needed, and cannot hope to long retain the confidence of his customers. In fact, he is not a watchmaker at all, but simply an apprentice or student, even though he be working for a salary or be his own master. There are undoubtedly many worthy members of the trade, who are not familiar with the making of a balance staff, who will take exceptions to this statement; but it is nevertheless true. They may be good workmen as far as they go; they may be painstaking; but they cannot be classed as watchmakers.
This article is intended for the benefit of that large class whose opportunities for obtaining instruction are limited, and who are ready and willing to learn, and for that still larger class of practical workmen who can make a new staff in a creditable manner, but who are always glad to read others people's ideas on any subject connected with the trade and who are not yet too old to learn new tricks should they find any such.
[Illustration: Fig. 1.]
Good tools, in good condition, are the most essential requisites in making a new staff. I would not advise any particular make of lathe, as the most expensive lathe in the world will not produce a true staff if the workman cannot center his work accurately and does not know how to handle his graver, while on the other hand fine work can be done on the simplest and cheapest lathe by a workman possessing the requisite skill. I will take it for granted that you use an American-made lathe of some kind, or a foreign-made lathe manufactured on American lines. It is advisable, though not absolutely necessary, to have three gravers similar to those illustrated in Fig. 1, A being used for turning the staff down in the rough; B for the conical pivots and square shoulders and C for the under-cutting. The other tools and attachments needed will be described as I come to them in use.
The balance staff should be made of the best steel, tempered to such a degree as to give the longest service and yet not so hard as to endanger the breakage of the pivots. Select a piece of Stubb's steel wire, say No. 46, or a little larger than the largest part of the finished staff is to be, and center it in a split chuck of your lathe. Be careful in selecting your chuck that you pick one that fits the wire fairly close. The chuck holds the work truest that comes the nearest to fitting it. If you try to use a chuck that is too large or too small for the work, you will only ruin the chuck for truth. Turn the wire to the form of a rough staff, as shown in Fig. 2, leaving on a small part of the original wire, as shown at A. After the wire is roughed out to this general form, remove from the chuck and get ready to harden and temper it. The hardening and tempering may be effected in various ways, and I am scarcely prepared to say which method is the best, as there are several which give about the same general results. One method of hardening is to smear the blank with common yellow soap, heat it to a cherry red, and drop endwise into linseed oil. Petroleum is preferred by some to linseed oil, but, to tell the truth, I can see no difference in the action of linseed, petroleum or olive oil. Be sure and have enough oil to thoroughly cool the blank, and a deep vessel, such as a large-mouthed vial, is preferable to a saucer. The blank will now be found too hard to work easily with the graver, and we must therefore draw the temper down to that of fine spring steel. Before doing this the blank should be brightened, in order that we may see to just what color we are drawing it. The main object in using the soap in hardening is that it may form a scale upon the blank, and if the heating is effected gradually the soap will melt and form a practically air-tight case around the blank. This scale, if the hardening is carefully and properly done, will generally chip and fall off when the blank is plunged in the oil, particularly if the oil is cool, and if it does not fall off of its own accord, it can easily be removed by rolling the blank upon the bench. If it does not come out clean, or if soap is not used, it may be brightened by again inserting in the lathe and bringing it in contact with a piece of fine emery paper or