Machining a large single cylinder crankshaft - GIF

[Altair]

Machining a large single cylinder crankshaft.




Previously:

Drop forging crankshafts - video
turning a giant crankshaft
Crankshaft hardening machine - GIF
Casting crankshafts - GIF
Crankshaft grinding machine - GIF

[uv8452]

As the operator I would be scared.

[Ralphxyz]

The cutting tool is only occasionally cutting?

[tonyfoale]

The cutting tool is only occasionally cutting?

The finished journal is offset from the main rotational axis so the workpiece is mounted eccentrically and the tool has to cut away more material on one side at the beginning, when it is close to size it will be cutting evenly all around.
This example is for a single cylinder but depending on the number of cylinders and the angular spacing it may be necessary to do several workpiece setups. For example a 120 deg 3 cylinder will need 4 setups, one for each crank pin and another for the main bearings.
The modern way uses CNC, then you do it all in one setting and move the tool in and out as the crank rotates to get the offset journals. However, just as in the example here at the beginning only part of of the workpiece will be touched by the tool.