Simple Oscillating Steam Engine - Crank


The crank was made from a piece of bright mild steel bar. The off-set for the crank pin was drilled using some packing in the 3 jaw chuck of the lathe.

Click for larger Drawing

 

 

 

 

 

 

 

 

The end of the bar was turned to the required diameter. Although only 6mm of length would be needed for the crank disc, about 12mm was turned to the final diameter to allow room for the parting-off tool.

 

In the same setting the centre hole for the axle was centre drilled, drilled and reamed to final size

Centre drilling

Drilling

Reaming

 

 

The crank disc was parted form the steel bar with the parting tool and a slow feed and speed.

Part way through the tool was retracted and a file used to debur both external edges.

Then the tool was advanced again to separate the part.

 

 

 

 

 

 

 

 

To drill the crank pin hole a piece of packing was used in the 3 jaw chuck to give the required off-set. Then the hole was centre drilled, drilled and reamed in the usual way.

The pillar drill could have been used for this hole but the lathe ensured the hole was a square as possible.

 

 

 

 

 

 

 

 

The crank disc was assembled to the axle using 'Loctite'. If preferred a grub screw could be used but the Loctite made a very good permanent bond.

 

 

 

 

 

 

 

 

Finally the crank pin was turned from a piece of 3m silver Steel. Exact length was unimportant.

This was also glued into place with Loctite.

 

 

 

 

 

 

 

 

 

 

Finished Crankshaft

 

 

 

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