It is best to use a low RPM, high torque drill to not dull the bit or overheat it. I use a Snap On 1/2 inch air drill that turns 800 RPM. My Blair bits last a long time. I also have used many Wurth 8mm bits that worked well.
Brad
Dorn Autocraft

Check out the Dorn's 69 Barracuda "Switchblade" in the Nov.2010 MCG
Check out the Dorn's refurbished 36 Ford in the Feb.2011 Street Rodder