[Radio Wrangler]

Bakelite isn't as inert as you might think. I'd go for mechanical methods over chemical unless I'd checked the chemistry didn't spoil bakelite.

I'd wrap the outer with something like sticky copper tape and then chuck it up and centre it in a 4 jaw chuck in a small lathe. If necessary, machine-up a small nest to match the draft taper of the knob outer, with a stub for your chuck to grip, or just chuck the outer of the nest.Grind the end of the shaft flattish to make drilling easier, then use a centre drill and drill a fine pilot hole, then a drill to remove the rest of the shaft. A tailstock chuck will make it easy to feed very gently and to limit the depth of drilling. You'll hear the grub screw as you try to cut the end off it (another reason for going slowly and gently with the drill feed.

David