Broken bolt drilling problems

[hella 325]

The alternator bracket bolt on my car broke off in the block and seized in ther...Im tyring to drill it out but every bit i get melts, what are the best bits to drill into hardend steel?

[Jordan]

Titanium coated bits. Buy good bits, not dollar store sets.

[hella 325]

where should i get these titanium bits? i got cobalt bits a lowes....are those crap?

[cthulu703]

Cobalt bits are the best bit for hard materials IMHO. It is the drill-bit of choice for stainless. I doubt the bits from Lowes are worth much, I bought mine from a machine tool store. I paid about $5 per 1/8th inch drill bit. I would dimple where you want to drill, start with a 1/16th inch drill bit and follow up with a 1/8th. Drill the biggest hole you can in it without going into the threads and use plenty of cutting fluid.

[hella 325]

yea.... roasted 8 cobalt and 4 tiatium bits =( what kinda shop would sell the good ones. i paid 3 bucks a peice for DeWalt cobalt bits

[Brew]

Get a left handed drill bit if you can. Chances are that it will unthread the broken bolt for you.

Also, if you are "roasting" bits, you are drilling too quickly. Slow it down a bit and use some cutting oil.

[hella 325]

well... teh small ones raost the big ones just dull....and they all shred. im goin to norther hydraulics tomarrow and getting some from there and some cutting oil

[cthulu703]

Also, remember that it is possible that you are destroying the small diameter bits because you are not turning them fast enough. Spindle rpm should be inversely proportional to bit size. There are charts for spindle speed versus bit diameter in books such as the Machnery's handbook. On material that work hardens it is important not to stop drilling after the you have started cutting. When you remove the bolt, be sure to chase the threads with a tap and using something like devcon threadlock on the next bolt. It helps stop the electrolytic reaction that seizes bolts in their threads and is a very mild threadlock. Usually used just to keep bolts from loosening under vibration.

[hella 325]

yea....i got more bits, taps and some high strength cutting hweels for the dremel and osme cutting oil....its time to attack it....

[hella 325]

OMG! my easy out broke off in the hole i drilled so now im back to where i was...only with a harder bolt......this is horrible.... :evil: :evil: :evil: anyoen have any bright ideas?

[hella 325]

the easy out is not drilling at all....im so pissed off....anyone ever have this happen? what should i do?

[AndrewBird]

If you killed a cobalt bit, something is wrong. The only thing I can think of that would do that is either too much pressure, not the right speed or maybe you had the drill going the wrong way. A sharp cobalt bit should have gone through that like it was butter.

Did you get the easy out that you broke off out of the hole and are no using another? If so and are having problems, make sure you first drilled the correct size hole. Then, put the easy out in the hole and tap it in a little with a hammer. Just enough to seat it intot eh bolt well. If it doesn't seat, then you need to drill the hole deeper. I would then either use a ratchet with a sqaure socket that is the right size or a tap holder. This will pevent you from twisting it at an agle and just poping it out of the hole. Go slow and don't reef on it. Keep constant pressure and it should come out.

[cthulu703]

Since you have just broken off an EZ out in the hole, you are now royally screwed. It is quite a bit harder than the bolt you were trying to get out. Hopefully, if it is a cheap EZ out you may still be able to drill it. If not, you need to get it to a machine shop. In the future avoid using the EZ out sets you find in chain stores. They are usually very surface hard, but weak in torsion. I had a similar experience with a motor cycle I had. I had to remove the head and have the machine shop get the bolt and EZout out. It destroyed the threads and I had to helicoil it. If there are any irregularities on the surface of the snapped off bolt, one other thing you can try is putting a torch on it and hitting it tangentially with a punch, like you are trying to unscrew it. If it starts turning, eureka, if not, I am very very sorry.

[hella 325]

well....yea the bolt is still in there...but i made a custom bracket and got the exisitng bracket to seat and stay right....should work fine. If i can find a buddy to do get it out i will...if not my custom bracket will hold fine

[Sean]

I've broken 2-3 easy outs trying to get some stripped bolts out. My dad broke one too. They snap like twigs, it's quite aggrivating!! :shock: