The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

May, 1921 18, where several partly finished pis- tons are seen in the foreground. The first operation on these pistons is to locate the casting in a chuck where a seat is turned at the lower end which is used in locating the part in subsequent finishing operations. The piston then is located as shown in Fig. 18, where it is carefully turned, leaving a liberal allowance for grind- ing. Next the grooves for the rings are machined. The hole for the pis- ton pin is bored and reamed in a horizontal boring mill, after which the piston is ready for finishing by grind- ing. Grinds Piston Rings Piston rings cast iron, accue rately finished on the sides to fit: the grooves in the piston. are The rites are bored and turned and cut off in the lathe from a. pot casting. Next the joint is milled and fitted. The joint is held 'together by means of a small dowel pin, while the sides of the rings are accurately ground as shown in Fig. 16. This method assures the sides being parallel within close limits. The: ext operation 'consists "ofan ishing the outside of the ring to an accurate fit with the cylinder. In this operation several rings are located on oue fixture.and ground at one 'setting. Piston rods for 2-cycle engines are hammered steel forgings, roughed out in the lathe and finished by grinding. This is a simple operation followed by methods known to every mechanic. Care must be_ exercised, however, FIG. 34--LARGE PLAIN GRINDING MACHINES ARE MARINE REVIEW FIG. 35--BORING CYLINDERS in machining these parts to make sure that the head of the piston rod that belts to the <piston «is. accurately. machined square with the body of the rod and that the part that fits the crosshead also is machined accurately USED FOR ACCURATELY ON VERTICAL BORING MILLS Connecting rods are hammered forg- ings with marine type crosshead and crank ends. The rods are turned and the ends "squared in* the lathe, while the inside of the forks are usually finished' on the slotter. Care is exer- FINISHING CYLINDRICAL PARTS