Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

As has been pointed out, it is the glass fiber content that does the damage. HSS drill bits get dull pretty quickly. As far as shearing boards, I wonder if there is a somewhat different cutting action taking place i.e. the shearing (at a microscopic level) breaks the fibers by tensioning them past failure. My guess is that any cutting action that results in lots of "rubbing" is a problem. The other concern with cutting any plastic (such as the epoxy content) is that there can be local heating at the cutting edge that can compromise the tool. Somewhat paradoxically, cutting holes in brass has less dulling effect on the tool than cutting a softer plastic.