Well, I looked for my osborn brush in the barn. It's in a real safe place, somewhere. Mine is an 80 grit, 4".
http://www.osborn.com/XTab.aspx?cat=ATB+Cup+Brush&grp=242TT04I had a friend make a threaded insert and weld it in, then chucked it up in the right angle drill. That's slower than optimum but works, too fast can burn.
I've used these on rugged hewing but they can carve and distort fast
http://www.osborn.com/XTab.aspx?cat=Abrasives&grp=462TT01This is the osborn and no finish
This is with an 80 grit flapwheel and water based poly.
The third log up is the old plate. The squirrely smaller logs were from an older building and added as basically framing to be furred and plastered over in an 1865 pop top addition. All the logs shown in both shots were very funky, they are much more "toucheable" now.