Re: OT where to buy a reverse drill bit locally?
A few quick hints for extraction:
1. 500 rpm or less---don't be fooled by "high speed drill bits". Drill bits are designed to cut, and too much heat will dull them quickly. So, use a quality electric drill with a progressive trigger, or (much mo betta) a quality air drill with an air regulator, so you can just mash the trigger for slow rpm goodness [img]images/icons/wink.gif[/img]
2. Drilling a small pilot hole is great for control and cutting effectiveness, especially when using left-hand bits. Some quality bits have pilot tips, but these aren't as effective.
3. Centering the bit in the object (stud, bolt, etc.) is paramount, especially for extraction, since the primary goal is to maintain thread integrity. Sometimes very difficult, since stuff never breaks off flush [img]images/icons/wink.gif[/img]
4. You get what you pay for, so a set of quality bits to go along with a quality drill is important. Regular high speed, Cobalt, Carbide, etc. -- can cost several hundred dollars for a set; make sure to take good care of them. I know, a set of $40 dollar B&D's is all you need, but try cutting into something really hard, like a broken off carbide bit---good luck [img]images/icons/wink.gif[/img]
4. For said emergencies, a set of Carbide Burr bits (or better) is a good investment, especially for chewing through metal quickly, as well as blasting through that $10 Cobalt LH bit that just broke off, 'cause your arm got tired and couldn't keep the drill straight [img]images/icons/laugh.gif[/img]
5. Be patient!! The slower and more careful you are, the more succesful you'll probably be---let's face it, ya prolly got into this mess because of impatience, now let's get out of it w/o costing a fortune!
6. Extractors come in all flavors---but be careful; alot of them exert pressure towards the theads, and are generally working against your goal, providing expansion inside when contraction is really what you want. Use the largest extractor possible, since they have less chance of breaking in the hole (been there, done that -- burr bit to the rescue [img]images/icons/laugh.gif[/img] )
6. If you do screw up again, its time for a Heli-coil [img]images/icons/smile.gif[/img]
Good luck [img]images/icons/laugh.gif[/img]