These heads were carved out of a 3-1/2 inch diameter cast iron bar. The ports will be attached to inside admission piston valves, inboard of the frame, controlled by Stephenson valve gear. They are angled at 50 degrees per the Brooks prototype.
The first operation was to turn the blanks on the lathe. The inside diameter is threaded 3/4-16 for the packing nut. A bearing was made from bronze for each head.
I used the above fixture to mill parallel flats, top and bottom and to rough out the profile between the flats by plunging with an end mill.
The roughed out profile is pretty ugly but it was a quick way to remove a lot of material.
I mounted a rotary table on an angle plate to finish mill the profiles between the flats where the crosshead guides will be attached. The last operation was drilling and tapping the mounting holes.
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