While waiting for the infill finish to dry, I decided to work on the cap screw. Steel, brass, turn as one piece … ? I thought I’d try something that should be quick and easy, just Loctite a cap screw into a brass cap. So I turned the head of a 5/16” cap screw to just over 7/16” (to get down to bare metal) and trimmed the head length to about 1/4”. Then I drilled a hole in the end of a brass rod and used a end mill (as a drill bit) to get a 7/16” flat bottomed hole. Then a test fit. Which didn’t want to come apart, I guess I don’t need Loctite. Pressed it home and called it good. It is good enough that I was able to machine the brass by holding the screw.
I think next time, I’ll just trim the head length and leave the diameter alone and bore the brass for an interference fit. The drill chuck isn’t all that rigid and the end mill wiggled a bit on entry.
I knurled around the corners (the knurl is rounded, not flat) by holding the knurling tool at various angles to the edges and to flatten out the ridges that created. A little work with a brass brush cleaned things up quite nicely. Lots easier than making a custom knurling tool.
The top is shaped so as not to dig into my palm, wish I could think of something more stylish.