Christopher Tidy wrote:

So is there a consensus about how many RPM the barrel that holds the
stones (or in my case, old bolts from a project car) should be turning?


30 rpm was just my guess while I was thinking about a design this
morning. Having done a little more searching online I've found two
commercial models which run at 45 and 52 rpm, so this gives a rough
idea.


RPM must depend on size.

There is probably an ideal FPM range, just like metal removal.
Might depend on the type of rock, so variable speed might be desirable.