Hi there. So I tried extracting a brake boss bolt with a left handed drill bit. now I need to extract the left handed drill bit as it broke off inside the boss 😃😃
I can't think of anything else but to take it to a professional to maybe weld on a new stud.
Unfortunately this one doesn't seem to be removable as there are no flat sides.
Anyone got any ideas?
Cheers!
by maxii95
9 Comments
Possibly drill and retap.
Could you weld a nut on to the broken piece, the heat may help too, if your not confident take to a pro thou, only my opinion
Probably wouldn’t be a job to tackle if you hadn’t done it before,
The shaft you were attempting to remove the bolt from is often threaded on the frame side and screws out with normal left loose thread. They are always lock tighted. If the portion behind the horizontal stay is blocky or bigger then needed for a weld it should turn right out. Length was not standard until late 90s so they were made to be swapable.
Weld a hex wrench in it. if you can’t get a welder, drill a hole and use a file to get the tip of a hex wrench pointy and then hammer it inside the hole.
As far as I am concerned, you have two options – take it to a machinist or a take it to a frame builder.
People telling you to try and drill it out yourself, with respect, have no idea what they’re talking about. No home mechanic is going to be able to *drill out* a hardened steel drill bit without specialized equipment, and no one with this sort of expertise is asking a subreddit how to do this job.
Apply a lot of penetrating oil, heat with a torch (not too hot, just a bit), cool it off, more penetrating oul, more heat, cool it off, use a Dremel with a small cutoff wheel to carefully make a slot in the bolt, then an exactly fitting screw driver or a quality bit to remove the bolt piece.
Wow, you’ve got yourself a real doosie of a problem here. The cheapest option is a new frame, by a long shot.
You could buy some ball end carbide bits, and use a dremel to burn out the extractor, and the snapped bolt. But it’s a very slow job, and you’ll likely slip off the extractor, and burn through the threads in the fixed boss. A good carbide burr is ~$20, although you can potentially do it with one of the Amazon sets where you can see the brazing (the one colour ones are usually HSS despite what they say) this is going to take a while, and likely won’t work.
A machinist would use EDM to burn the extractor out, and likely do the snapped bolt at the same time, but it’s going to be expensive.
Having a new boss brazed on isn’t too expensive, but still more than replacing the frame.
I’ve never had any luck shattering broken taps or extractors.
Unless you are OK with the risk of trashing your frame this is not something you can sort out yourself.
To drill out a hardened drill bit you are looking at least a cobalt drill preferably in a drill press with the frame clamped in place in a suitable jig. If it was just a canti bolt these can be done but now you have a hardened drill bit snapped into a broken canti bolt.
If you have a local machine shop or fabrication engineer they can do it and if you don’t piss them off when you ask and excercise patience so they can do it in between other jobs they probably won’t charge you all that much either.