I had problems with getting rid of burn marks from the rounded inset corners of a ceramic sink cutout. I just could not get in with a profile sander or by hand.
Just by luck I stumbled on a set of small drum sanders for use in an ordinary drill. The smallest fitting perfectly in the 12mm profile of the cut. 2 minutes later the job was done and the drum sander set had paid for itself. (about £8)
Cheers,
Raymond.
