[Illustration: Fig. 26. Fourth Operation--Finishing the Bore and Outside]
After the thread is finished, the turret is turned to the third station as shown in Fig. 25, and tool _K_ for the inner recess _B_, Fig. 22, is brought into position and fed to the proper depth, as determined by another cross-stop. The turret is also locked in position for this operation. The finishing cuts for the bore and the outside are next taken by a box-tool which is shown near the end of its cut in Fig. 26. This box-tool is similar to the one used for roughing, but it is equipped with differently shaped cutters to obtain the required finish. The outside turning tool has a straight cutting edge set tangent to the cylindrical surface and at an angle, while the boring tool has a cutting edge of large radius. An end view of this box-tool is shown in Fig. 27. A reduced feed is employed for the finishing cut, and the speed is increased to 130 feet per minute, which is the same as that used for roughing.
[Illustration: Fig. 27. Fifth Operation--Rounding Ends, Scoring Large End, and Cutting Off]
During the next and final operation, the turret, after being indexed to the position shown in Fig. 27, is first located by a stop of the "A" group so that the cutting-off tool _R_ in front can be used for rounding the corner _b_, Fig. 22. The stop lever _L_ is then shifted and the turret is moved to a second stop of the "B" group. The corner _c_ is then rounded and the shell is scored at _d_ by two inverted tools _S_ and _T_ at the rear, after which the finished work is severed by the cut-off tool at the front. The cross-movement of these three tools is controlled by positive stops on the cross-slide, and the latter is moved to and fro by hand lever _O_. After the shell is cut off, the stop _M_, mounted on the turret, Fig. 26, is swung into position, and the tube is automatically fed forward to the swinging stop by the roll feed, as soon as the chuck is released by operating lever _Q_. This completes the cycle of operations. A copious supply of lubricant is, of course, furnished to the tools during these operations, and the two boring-tool shanks are hollow so that lubricant can be forced through them and be made to play directly upon the cutters.