Crankshafts were turned from EN24t. The three blanks were first reduced to 16mm dia shafts then held in a collet block to mill away the surplus around the crankpin. This could of course be done on the lathe but I prefer to do it thus.
The embryo cranks.
The pins were roughed to .5mm plus and the rear face of the web cleaned up. The fixture, made many years back, is ideal for this op allowing, within it's limit on the face plate, an infinite crank throw.
Set in the soft jaws the shafts were reduced to plus .5mm on diameters. Roughing these En24 shafts is one of the rare occasions that the Myford sees a tipped tool.
Ready for the final ops.
With the shafts now ready for finish turning this was the time to machine those front bearing housings on the cases so that the shafts could be test fitted as finished. A new expanding mandrel was made for this op to ensure co axial alignment. The case is locating on the main bearing diameter and being clamped (by expansion) inside the shaft hole.
With these done it was time to set up to finish the shafts. First they were held in a collet and a centre put in the web face then this little drive plate was pressed into service yet again, the centre pin being skimmed at 30 degrees to ensure concentricity.
Part one here. Part two. Part three. Part four. Part five. Part six. Part seven
