I found a Proto 3/8 ratchet the other day, and after getting it working (Froze up), I decided I'd do a regrip.
I found some green Stanley screwdrivers at Lowes to use as the handle. I clamped the blade of one of the 'drivers in a vice with the handle facing down. I wrapped the top of the handle with a rag, and put some channel locks around the blade so it sat on the top of the handle. Then simply tap the handle off by hitting the pliers with a hammer.
I then took a caliper and measured the knurled handle on the ratchet. It came out to be about .635". So I found a 5/8" drill bit, chucked the handle in the lathe using the three jaw chuck, and bored the handle out.
Next I lined the logo on the handle up straight with the head of the ratchet, and using a mallet, I tapped it on. No more knurled crappy handle!