We had some cast-iron cylinder bushings to bore and turn for locomotives. As there were about twenty-five bushings in the lot to be machined, and we were in a big hurry to get the job out, we rigged up a special tool for the job. Fig. 152 shows the tool, and the way in which it was attached to a lathe. The Boring head A, which is keyed to the bar B, had six dovetailed slots cut across its periphery. These slots were used for holding hard-wood blocks, which fitted closely into the bore and guided the bar. A boring tool was clamped in the groove across the head, as shown at C. The split sleeve D, which was fastened to the lathe carriage, supported one end of the boring bar, and the sleeve was clamped to the bar when boring, as the feeding was done by the lathe carriage. The bar was also supported by a steady-rest, as shown at E. Before the boring bar was placed in position, the end of the cylinder was trued up, as the outer end of the cylinder had to be supported by a steady-rest F. In starting the cut, it was necessary to steady the bar by clamping the sleeve D close to the boring head; but when the head had entered the cylinder, the sleeve was moved out as far as the bar would permit, and again clamped to the bar. The hard-wood blocks referred to were used for the finishing cut. The cylinder bushings bored in this way were absolutely straight and true, and the work entirely satisfactory. After the bushings were bored, they had to be turned to suit the cylinders, and these centers were also made for the job. Fig. 153 shows the centers, and Fig. 154 shows how they were used. Center head G is cast with three arms 120 deg. apart. A slot H is cut in each arm, and lugs I are fitted in the slot, allowing for the required adjustment. The inner end of each lug is tapered off at 45 deg. angle, and the head of the stud L has the same taper as the lugs, and is screwed into the center head G, to adjust the lugs to suit the bushings. After the proper adjustment has been made, the lugs are locked with the bolts M, then the job is placed on the centers of the lathe and turned off to the required size.

Fig. 152 - Boring a locomotive cylinder bushing.

Fig. 153 - The adjustable centers.

Fig. 154 - The centers fitted into the cylinder.