I have a Record BDS150 belt/disc sander and have been using toolstation 150mm adhesive discs 120 grit and they seem to not last very long before they become a polisher instead of a sander so is this the nature of the beast or can you get better sanding discs which last longer. I use the sander mainly for squaring pen blanks and taking them down to the brass tubes maybe I should use 80 grit.?