yeah so replacing my exhaust manifolds is turning into one of those projects. I managed to bust off not one, but count 'em 2 high speed steel drills in one of the busted manifold studs. (they were both broken off inside the block, go figure) Should I go to a Titanium Nitride drill or is there something better?

I'm going to hog out the hole and weld / drill / tap a new one, but I gotta get those old drills out, and can't get around them enough to drill all the way around.

ideas are appreciated! Thanks folks.

 

Find out what is the next larger drill size recommended for a suitable helicoil then buy a solid carbide drill bit or end-mill bit of that size. After drilling, tap for that hecoil size. It'll be very slow. I've done that before. By the way, drilling at slower speed would get better result, let's say about 350-500rpm range.

 

Any chance of grabbing onto the broken drill bits with needle nose pliers or something similar and backing the stud out?

 

no - they broke of flush with the face of the bolt. I couldn't get that lucky! I am going to pick up a helicoil in the correct (new) size as well and see if that will work instead, since I'm going to be at ace hardware anyway. I might actually just tack the helicoil in with my TIG rather than filling & drilling. Amd I didn't think of an end - mill. that might be the ticket since I've already got part of the hole drilled out, I just need to finish it. I will check and see if i can get a small enough one and do it that way.

it wasn't a speed issue per-say, but more of the angle I was working at and having an unsteady, heat soaked afternoon. I never start these projects on cool days.

At least FORD was nice enough to drill the manifold holes to 10mm in the first place, so those two holes are going to be different than the other 6 are. Oh well. The excitement.

 

If room permits to clamp a drilling jig, make a drilling jig out of aluminum or wood would help steady the hand.

 

i went through that about 9 months ago 3 broke off no way toremove it with a reout had to get a guy who can laser it out its a bout 2-300 bucks without removing the heads