Fig. 1314.
When a number of small pieces of duplicate form are to be turned by hand, a great deal of measuring may be saved and the work very much expedited by means of the device shown in [Fig. 1313]. It consists of a tool stock or holder, the middle of which, denoted by a, is square, and contains three or four square slots, with a set-screw to each slot to hold different turning tools. Each end of the stock is turned parallel, as denoted by b, c. In [Figs. 1313] and [1314], d, e, and f are the tools, and g, h, are the set-screws.
[Fig. 1315] represents top and side view of a plate, of which there must be two, one to fasten on the headstock and one on the tailstock of the lathe, as shown in [Fig. 1316]. In [Fig. 1317] the manner of using the tool is shown, similar letters of reference denoting similar parts in all the figures.
Fig. 1315.
Fig. 1316.
The plates p p are bolted by screws to the headblock h and the tailstock t of the lathe. The tool holder is placed so that the cylindrical ends b, c, rest on the ends of these plates, and in the angles p′ p′. The cutting tool d is sustained, as shown, upon the lathe rest r. In use the operator holds the stock a in his hands in the most convenient manner, using the tool e as a handle when there is a tool in the position of e. The cutting point of the tool is pressed up to the work w, and the feed is carried along by hand. It is obvious, however, that when the perimeters of a b meet the shoulders o o, [Fig. 1315], of the plates p p, the tool cannot approach any nearer to the diametrical centre of the work; hence the diameter to which the tool will turn is determined by the distance of the shoulder o of the plate p from the centre of the lathe centres, as shown in [Fig. 1316] by the line l. In carrying the cut along it is also obvious that the lateral travel of the stock or holder must end when the end of the square part a comes against the side face of either of the plates. In the engraving we have shown the tool d cutting a groove in the work w, while the shoulder of the holder is against the plate fastened to the lathe tailstock t; and so long as the operator, in each case, keeps the shoulder against that plate, the grooves upon each piece of work will be cut in the same position, for it will be observed that the position in the length of the work performed by each tool is determined by the distance of the cutting part of each tool from the end of the square part a of the tool holder. All that is necessary, then, is to adjust each tool so that it projects the proper distance to turn the requisite diameter and stands the required distance from the shoulders of the square to cut to the desired length, and when once set error cannot occur.