broken bit in bolt

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Nissinator1996

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i was drilling into a broken bolt(in the crankshaft) and i broke the drill bit all the way down into the bolt any idea on how to get it out or what to do
 

Jake.B

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Is it flush or can you grip it? If not i would either try an EZ out, left hand drill bit, or drill some more with a different bit.
 

Doc Sprocket

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Ooohh. That's a tough one. You'd need a pretty dang hard drill bit to drill out a drill.

It may be risky, but if you have a plumbing torch, you might be able to kill the temper of the broken bit by getting it really hot and letting it cool slowly before drilling.

Another major problem is trying to centre the "rescue" bit on the broken bit...
 

Nissinator1996

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i cant grip it in anyway and i dont have a torch....but let me ask this does a chain driven clutch use a bolt to keep it on???
 

Doc Sprocket

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Usually. You could try a clutch with setscrews (most have them) and do the following-

Position the clutch in good alignment on the shaft, and snug up the setscrews. Then- remove the setscrews and pull the clutch off again. Using a centrepunch, mark the centers of where the setscrews made marks on the shaft (and often, the key). Chuck a 1/16" bit into your favourite drill, and drill a shallow divot on the spot. (maybe 1/32" deep). Reinstall clutch, and apply blue #242 Loctite threadlocker to the setscrews and reinstall.

If you're quite careful about it, you could also try cutting a narrow groove around the circumference of the shaft, and using a circlip or snap ring as a retainer in addition to the above.
 

Doc Sprocket

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Another "last-ditch" idea might be to carefully hacksaw the end off the the PTO shaft, leaving the bit sticking out for rescue with vise-grips. I say "last-ditch" because if everything else fails, you're into a new crankshaft, anyway.
 

Rustydog2010

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depends on what bit he used to start with. Some of those realy **** chinese bits are pretty soft, i reckon a decent/harder bit might get through one

I dont no, I have my suspicions. Sure they are poor quality, but they will be far from easily 'drillable'.

Drills are pretty brittle, what if you got a punch and just went at it? Try and break it up. I have done that to a broken tap. Used the other piece of the tap and ground it to a point. Just went at it, slowly broke it all up.
 

fowler

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why are u drilling the hole
how big is the drill bit

u will need a cobolt drill bit
they power though most things
a standard HSS bit will not drill a crap HSS bit

a tap is alot brittler than a drill bit
they bend first

the bigest isue is getting the bit to drill the broken bit and not vere off into the bolt

it will want to take the path of least resistance
 
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