Going by the drawings and the steps they suggest and what parts could be bought in I would make a ball one now. The yellow South Bend drawing I posted yesterday makes the mechanism pretty clear, here’s a photo, also from practicalmachinist.com, https://www.practicalmachinist.com/v...9/#post1859229

I’m curious if there are problems with them, though, I wonder why they aren’t more common compared to the finger ones.