Connecting Rod
10.03.2004
The connecting rods are also made of GGG using sand casting. As always with a cast part, it is not that easy to mentally place the part to be created in the cast part in such a way that it does not stick out of the casting later :-) . I first pre-milled the straight surfaces of the pin bearing on the milling machine in order to determine the axis of the connecting rod.
The connecting rod was then put on the lathe. At first I just clamped it into the four-jaw chuck. A connection had been cast onto the upper end of the fork. After precise alignment, a centering hole could be made here for the rotating tip. All radii and the curvature of the fork head were turned freehand.
Back on the milling machine, the connection on the fork head could now be cut. All of the inner surfaces of the fork were finished using a milling cutter of the appropriate length.
The holes for the crank pin and crosshead bearings were then turned out on the milling machine. Machining in a clamping position ensures precise alignment. The fork ends were given the final touch (milling) on the rotary table. Centering is very easy here using the pin hole.