A client who is building a 'Schools' class locomotive asked me to make the regulator for it, using a proprietery casting he had purchased. The first step was to face the casting in the lathe, then drill passages and two valve ports, followed by tapping various points on the body. The valve disc and operating links were cut and filed from 1/8" brass sheet ..
The linkage is connected via 7BA phosphor-bronze screws, and is actuated from the cab via a squared-off 1/8" diameter 316 stainless rod ..
Mating faces of the casting and valve disc were polished to ensure steam-proof closure …
and were lubricated with a light smear of silicon grease before final assembly. Prior to that though, the mounting projection on the valve body had to be filed to match the 4 3/16" I.D. of the boiler shell, and the casting trimmed to clear the rim of the steam dome aperture. The final step was to fit a spring and nut to the valve spindle. The spring is currently stainless steel, though a beryllium copper replacement will be used once one is located ….