Fig. 6. Lathe Side-tool for Facing Ends of Shafts, etc.
Facing the Ends Square with a Side-tool.—Everything is now ready for the turning operation. The ends of the piece should be faced square before turning the body to size, and the tool for this squaring operation is shown in [Fig. 6]; this is known as a side-tool. It has a cutting edge e which shaves off the metal as indicated in the end view by the dotted lines. The side f is ground to an angle so that when the tool is moved in the direction shown by the arrow, the cutting edge will come in contact with the part to be turned; in other words, side f is ground so as to provide clearance for the cutting edge. In addition, the top surface against which the chip bears, is beveled to give the tool keenness so that it will cut easily. As the principles of tool grinding are treated separately in [Chapter II] we shall for the present consider the tool's use rather than its form.
Fig. 7. Facing End with Side-tool and Turning Work Cylindrical
For facing the end, the side tool is clamped in the toolpost by tightening the screw u, [Fig. 5], and it should be set with the cutting edge slightly inclined from a right-angled position, the point being in advance so that it will first come into contact with the work. The cutting edge should also be about the same height as the center of the work. When the tool is set, the lathe (if belt-driven) is started by shifting an overhead belt and the tool is then moved in until the point is in the position shown at A, [Fig. 7]. The tool-point is then fed against the end by handle d, [Fig. 5], until a light chip is being turned off, and then it is moved outward by handle e (as indicated by the arrow at B, [Fig. 7]), the carriage remaining stationary. As the movement of the tool-point is guided by the cross-slide D, which is at right angles with the axis of the work, the end will be faced square. For short turning operations of this kind, the power feeds ordinarily are not used as they are intended for comparatively long cuts. If it were necessary to remove much metal from the end, a number of cuts would be taken across it; in this case, however, the rough stock is only 1/8 inch too long so that this end need only be made true.
After taking a cut as described, the surface, if left rough by the tool-point, should be made smooth by a second or finishing cut. If the tool is ground slightly round at the point and the cutting edge is set almost square, as at C, [Fig. 7], a smooth finish can be obtained; the cut, however, should be light and the outward feed uniform. The work is next reversed in the centers and the driving dog is placed on the end just finished; the other end is then faced, enough metal being removed to make the piece 141/2 inches long, as required in this particular case. This completes the facing operation. If the end of the work does not need to be perfectly square, the facing operation can be performed by setting the tool in a right-angled position and then feeding it sidewise, thus removing a chip equal to the width of one side. Evidently this method is confined to comparatively small diameters and the squareness of the turned end will be determined by the position of the tool's cutting edge.
