Stuart No 4 Steam Engine

[f350ca]

There's lots I should be doing but gave in and started machining my new toy.
This part houses the cross head (I think thats what its called) that restrains the piston rod. The top face has to be perpendicular to the bore or the piston rod would bind in the packing. The bottom of the legs has to be perpendicular or the connecting rod would bind as the crank rotated.
To get a reference surface I cleaned up the bore and made an expanding mandrel to hold it, then machined the top and bottom face. The mandrel seamed to work well but there was a hard spot on the edge of one of the legs. The interrupted cut on the legs must have shifted the raw bore on the mandrel, saw a couple thou runout on the top face after finishing the bottom. 





To bring the two faces back parallel I ground them.


With the faces parallel and the OD available to dial it in I mounted it on a tooling plate and cut the bore for the cross head. Have a slight chatter at the top but left a half thou to finish the bore with a lap.


Drilled the necessary holes while it was mounted.

Pleased with the powder coat finish, no chipping at the edges where I machined.