What's the best drill bit to use for broken stud?

they can turn the stud out, once you have drilled it sufficiently to remove the pressure, they won't generally though, stud extractors will only work, if you can get a good purchase on and you can heat the stud up to a cherry red, but if you could do that, then you should have before the stud snapped,

on Gs'ers I normally just end up drilling progressively bigger, until I can either pick the remaining threads out and re Tap, or if it's slightly off centre, drilled out to helicoil size and re Tapped,

a good centre punch is an essential start, get it in the centre of the stud and keeping it straight and true is much easier,

had to drill out 6 studs this morning on a boxster, not fun!

Not much point in doing that. The stud is stuck fast due to corrosion, which in turn has effectively increased the stud diameter, the very reason it won't move. What's the point in applying heat when all it will do is increase the size further?

Heat should be applied around the local area to the stud to create expansion of the female thread, not the male (stud) thread.
 
Ref post #21

I didn't realise you couldn't edit a post in this section! I wanted to remove my post on the grounds I think I may have misunderstood what Ian was suggesting.
 
Apologies to all.
I should heed my own post and ... stop posting :blush:
As i see the 'rules' are different in The Font Of All....
Sorry for that.
Delete my 'contribution' Mods.
 
My apologies for not making it clear, the heat is to both expand the stud and boil off any thread lock, which is used when manufactured, once cooled, forced or otherwise, to warm, stud should wind out without snapping!
 
Seriously:

One with a left hand thread. Yes, and, of course, the drill running backwards.
You have a good chance the broken bolt will self extract.
Myke
 
If you are asking this question, you should not be attempting the job, but leave it to a pro, who would find it easier to do if you haven't already made a rat's-ringpiece of the job by following 'advice' from a few non-pros on a forum....... :D
i completely agree with the above:thumby:
i have lost count of the number of threads on this forum where chaps have dived in to drill bolts/studs out and have bollixxed the job completely:blast
you are not going to succeed in drilling a high tensile or forged bolt with cheap shit chinese drill bits.
still,looking on the brighter side of things ,it keeps me in a job:D
 
With due respect what a croc of shit.

I sell high end cutting tools to the engineering industry.
Cobalt is the way to go but 9 times out of 10 you will fcuk it up as you will almost certainly not be able to drill dead center.

My success rate on mates bikes is 6 out of 10.

Then you will get a carbon steel left hand stud extractor which will break and you will be in double shit.

Take it to somebody who knows what they are doing Steptoe for instance
 
If you are asking this question, you should not be attempting the job, but leave it to a pro, who would find it easier to do if you haven't already made a rat's-ringpiece of the job by following 'advice' from a few non-pros on a forum....... :D

Absolutely, especially when the advise isn't to resharpen the drill but to chuck it :D
 
With due respect what a croc of shit.

I sell high end cutting tools to the engineering industry.
Cobalt is the way to go but 9 times out of 10 you will fcuk it up as you will almost certainly not be able to drill dead center.

My success rate on mates bikes is 6 out of 10.

Then you will get a carbon steel left hand stud extractor which will break and you will be in double shit.

Take it to somebody who knows what they are doing Steptoe for instance


You sure your not getting a stud extractor and an easy out mixed up?

You know, a stud extractor that grips around a stud, instead of an easy out, that screws anti clockwise into a drilled hole, then snaps, what kind of high end tools do you sell like :D
 
I've had success in the past by drilling a hole the best I can (usually off centre) and then hammering something slightly tapered into the hole like a Torx bit then using an impact driver (manual type) and hammer.
 
Ive had success arc welding a nut onto a broken stud. Before welding there was no way it was coming out. But the extreme heat of arc weld broke the corrosion presumably because the steel expanded enough to make some scar for it to unscrew. Anything snapped off flush has to be drilled. Good luck, if its a stainless stud. That stuff is a nightmare to drill.
 
Do not use easy outs....they are the fingers of the devil...I also would not drill a small hole and then go up in 1mm increments..good chance of the drill snatching and trying to screw itself into the hole and then breaking, same with left handed drills.Also the same when you drill through the bolt, if there is a gap at the end.

If the bolt was tight enough to snap off, the chance are it will not just unwind.

I have drilled hundreds of snapped bolts out in the last 25 years or so, most success with carbide drills. If you can make a jig to help, so much the better.
 
nope

Not much point in doing that. The stud is stuck fast due to corrosion, which in turn has effectively increased the stud diameter, the very reason it won't move. What's the point in applying heat when all it will do is increase the size further?

Heat should be applied around the local area to the stud to create expansion of the female thread, not the male (stud) thread.

thats not how it works ,,, it may not work in this case , but in general , you heat the stud ,,, it expands yes , all metals expand as they are heated ,,, but as its constrained by the surrounding metal , it actually forces its self tight against the hole ,,, then as it cools it shrinks again , but back to a size that is now smaller than it was to start with. then lube it , and have a go , when its cold ,,, also the heating action and its related expansion crushes the rust , and it frees as its cooling too ,,, or thats my understanding
 
thats not how it works ,,, it may not work in this case , but in general , you heat the stud ,,, it expands yes , all metals expand as they are heated ,,, but as its constrained by the surrounding metal , it actually forces its self tight against the hole ,,, then as it cools it shrinks again , but back to a size that is now smaller than it was to start with. then lube it , and have a go , when its cold ,,, also the heating action and its related expansion crushes the rust , and it frees as its cooling too ,,, or thats my understanding
Yes, more chance of removing a stud or any other fitting when it's been heated :thumb
 


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