Disc Rotor Refurb?

A new 6" rotor is only about twenty bucks, but I've accumulated a
few rotors that *look* ok, but pulse badly.

Tried boiling in water for awhile on the latest one, but no
change.

I thought sand blasting for a moment, and then it seemed like
that would be asking for irregularities in thickness.

Anybody got a tried-and-true method of refurbishing a rotor that
doesn't require a machine shop?
--
PeteCresswell