Originally Posted by
StadiumRC
Best advice I know of is to invest in quality tools. I started stripping Allen heads a lot a while back and then finally decided to buy some MIP Thorp wrenches. Best move I ever made. They are the best hex wrenches I have ever owned, and I have not stripped a screw since. You will pay around $11-13 per wrench, but they are worth every penny. They come in metric and standard. Seriously, don't underestimate the difference a top quality tool can make. The MIP wrenches are American made, and they will last forever.
+1 on the tools, MIP is really good stuff, but there are many good options out there. They are worth the extra you have to pay over the cheap forged tools you get from the big chain stores. A precision machined tip will get a much better bite, and may even be able to grab what is left at the bottom of that "stripped" screw and remove it anyway.
Failing that, stripped screw extractors can be an option on all but the smallest of screws. You can find them online or in these chain stores. Your mileage will vary with them though. The dremel idea to put a slot in works well too, but will also tend to leave a small cut on either side of the screw in whatever part you are trying to remove. And once you get enough of the screw backed out to grab it with vice grips you have won the battle.