Set up on a lathe for drilling out broken bolts

[Paul Alciatore]

I have four words for you and your friend:

Left hand drill bit

They are my first "go to" tool for broken screws and bolts. The great thing is you almost never have to actually drill through the stub. They usually just back out from the torque and vibration before the drilling proceeds even one thread pitch into it.

When I said the first tool, that does not mean that I do not give it a good soak with penetrating oil. My favorite is Kroil and I like to give it hours or even over night to soak in. On really stubborn ones, striking it with the center punch while soaking can also help. You need to make a dimple in the stub anyway so using it to help the penetrating oil to wick in is a bonus.