[john]

I have only been stating what has worked for me. All masonry bits we stock at work are carbide tipped. "I" would use a hard metal bit (cobalt) instead of a concrete bit (masonry). Just my opinion. Stay OT.

If you are removing bits, you are headed in the right direction. Odds are that your die grinder spins quicker than you drill. You could try putting a bit on the die grinder if you want or a rotozip bit.