- is ordinary, grey cast iron! This I will be able to machine with my small mill and lathe.
Since they were going to melt a batch of the right stuff, I went to the foundry again, and tamped eight molds in a few hours...
A pair of cope and drag frames are ready to be put together. Note the nails pushed into the sand between the spokes of the wheel - these prevented the sand breaking up when I removed the pattern. (And the yellow color in the photo is because they use sodium vapor lamps for illumination in the foundry!)
Fiery stuff! My frames, made of pine (quite resinous, actually) caught fire and smoked a lot... A moment after shooting this picture, I was busy covering the smoldering frames with foundry sand.
My castings in a bead-blasting chamber. After a few minutes of bombardment with zillions of high-velocity 1/32" steels beads, the castings were nice and clean.
What's this? Six deformed "Starship Enterprise" models?
The "Right Stuff", anyway!
Just a little footnote, after a day in the foundry...
Link work
The Walschaert links have kept me busy in the workshop the past two days. Instead of messing with marking fluid, and scribing the outline on the steel, I made a few photocopies of the original works drawing to the exact 1:8 size - easy with a computer! After spray glueing the drawing to a suitable piece of steel, I was ready to make chips!
The radius of the link is 109 mm (a little over 4"), but since my rotary table is only a 6" model, I used a sturdy piece of brass, 10 mm / 3/8" thick, as an extension. Taking light cuts, this worked well. (I had of course pre-drilled the slot so the milling work would be easier...)
Cutting out the link piece with a slitting saw in the lathe.
And here, after quite a few hours of fiddly work, is one of the links mated with the die block. The trunnion piece is still in the works...