The 2-cylinder Shay has a bore and stroke of 2″ x 2-1/4″.

I started by face milling one end and then flipping the casting to make sure both surfaces were perpendicular. Once the cylinder ends were “square”, the casting was bored.

 

Then the steam chest faces were machined flat.

 

The 2 steam ports and single exhaust port were then machined. The center exhaust was milled slightly larger which means the D-valve dimensions will need to widened to accommodate.

 

Drilling and tapping the holes for mounting the cylinder heads.

 

To machine the angled steam passages on both ends of the cylinders,  I fabricated an aluminum block fixture to which each cylinder was mounted and clamped in the mill vise at 22°.

 

Machining the steam port passages.

 

Turning the lower cylinder head.

 

Boring the lower cylinder head for the piston rod.

 

Tapping the bore for the piston rod packing nut.

 

Test fitting the lower cylinder head with the piston rod in place before the head bolt holes were drilled.

 

Turning, tapping, drilling, and parting off the packing nuts.

 

Completed piston rod packing nuts.

 

Packing nuts installed in the bottom of the lower heads.

 

Quick test fit of the upper heads.

 

The upper cylinder heads after drilling all the bolt holes. I also turned the tops of the cylinders to match the diameter of the heads.

 

I ordered four small brass cylinder petcock valves and machined the bosses onto which they will be mounted.

 

Then I tapped threads for the valves and drilled the tiny steam relief ports.

 

I also drilled and tapped two mounting holes (one in each cylinder) for linkage standoffs which will eventually connect and control all four petcocks.

 

The four petcocks temporarily fitted. Use of thin copper or brass shim washers will ensure the valves are positioned correctly when tightened.