Ned Simmons wrote:
On Mon, 13 Jul 2015 16:59:44 +0000 (UTC), Cydrome Leader
wrote:



I suspect it has something to do with the angles they bits are cut. The
cobalt stuff from a good hardware store is usually 135 degrees. I seem to
wear the tips out real quick, large or small. Never really figured out
why.


Are you wearing the edges or chipping them? Common high speed steel
(M2) is tougher than cobalt high speed steel (M42). M42 is more wear
resistant and has higher heat tolerance. The edges on M42 drills will
chip much more easily than common HSS drills, so I don't personally
think they're a good choice for general use in hand drills.

It's wear. The tips go dull and seem worn as If I drilled into a brick or
something.