Cylinder valves for triple, and a neat method for cutting thin grooves.
The triple expansion steam engine now has a valve in each cylinder head. They are manually controlled, not automatic, and I guess that is the reason they are called “false” valves.
The body of each valve was shaped in the CNC lathe, using software called “Ezilathe”. There is a lot of good software for CNC milling machines, particularly Mach 3, but not much for lathes, at least for the non professional user. “Ezilathe” is a free program (currently), works brilliantly, and was written by my friend Stuart. It has an inbuilt simple CAD program, automatically generates G codes, and has a G code editor. It also has a terrific, easy to use threading facility. It has an accurate simulator, and a tool editor. Do a search on CNC Zone to download a copy.
One problem which I experienced with these valves was that the thread which secures the valves to the heads, stopped short of the expanded hexagon part by about 1mm, and I needed to turn a very narrow groove in the stem to allow the hexagon to screw down hard on the head. I do not have a lathe narrow grooving tool with enough reach to do this, so the following photo shows how it was done…