Y'think? That's 51.6% faster than your ideal. Why didn't you slow
down the lathe? Or did that speed work best with the density of the
larger diameter brush?

Jawohl, Herr Jaques! I slowed down the lathe to 550 for the 10" wheel, and everything works perfectly now. This wheel should last for years, so I will stop fretting about finding 3" wheels that are real brass.

Great. Glad I could help. It's amazing the simple things we can
overlook, or perhaps, are too lazy/hesitant at the moment to change
things.

I don't know why I didn't try to match the surface speed when I got the big wheel. I guess 550 just seemed so slow!