I quickly cut out drilled and rounded 4 arms for the piston head. A this point, my plan was to carefully band-saw then file them down to the right length and curvature. They felt very rigid though, so I decided to take a chance and cut them with the lathe.

This setup is kind of scary.

I was seriously gritting my teeth as I creeped the tool into the path of the spinning arms. It worked great though! It didn’t stall or explode or anything at all. It cut off nice chips with a steady tak-tak-tak-tak-tak.

I turned the arms down until the outer diameter was 3.74 like the other pieces. The fit was a bit tight though, so I put it back in the lathe and took off another .02, now it has a little wiggle room, which is good.

And, the finished part. Not my prettiest, but very cool.

I spent a relatively short evening making the piston shaft. I cut the threads using the treading mode on the lathe.

I apprehensive about it but it turned out to be pretty easy. Let it be known that the threading on the lathe is not as difficult as it seams.

One unanticipated benefit was that I was able to creep up on the right minor diameter and try the fit for the last few passes until it was just perfect.

Here’s the complete piston. Pretty spiffy eh?