The piston was turned to just over width and the centre drilled and tapped for the piston rod.
It was then fitted on the end of the piston rod to have it taken to diameter, cut the slot for the packing and face the two sides of the piston so it ran true (I know fussy, fussy
)
The piston fit passes the drop test:
It glides slowly to the bottom of the cylinder:
Time to look at the valve face: I've fly cut the face..
Now I am checking the dimensions... the width is a bit tight (undersized by 0.1mm before skimming square) I also noted that the inlet port dimensions are not on the drawing
They are half the width of the exhaust port, which is the same dimension as the lands between the ports and we can also check with the pocket dimension on the valve
So 4.76mm by 12.7mm exhaust, 2.35mm land, 2.35mm by 12.7mm inlet ports. I note the dimensions of the studs for the steam chest are not on the drawing. More opportunities to drill through from a cover - the way things were
Jo