Re: Broken studs
Cobalt drills are very tough but can be on the brittle side. That drill should have no problem cutting the stud material. Keep the RPMs on the low side and keep the preasure up to actually sheer the material and not burnish. Given that you drill is cobalt check the tip and inspect for a chipped or damaged drill point. If you have damaged the cutting edges the battle is lost. As a side note any metal cutting drill bit should make mince meat out of these studs with proper speeds and feeds. Using a left handed drill is of course the best bet as mentioned because it will help back the stud out as it drills.