removal of a fubar-ed crank bolt head

bluechair84

I've spent the last hour trying to mangle off a knackered crank arm (left) and a rounded out allen bolt. The bolt is up too tight to get off, I've tried knocking in a flathead but I couldn't get enough purchase. So, as the crank arm is no good now, I tried cutting through the crank arm to cut some recess into the bolt to use a flathead in. Still no good as the BB axle is reached before I can get deep enough into the bolt. So I've tried cutting the bolt in half through sideways, but again I'm hitting the axle before I'm all the way through. I've tried knocking in a 6mm and that won't go in enough to turn it out.
I've pulled out the drill as well but I haven't the right bits to drill it out. Are crank bolts hardened steel? Is my only remaining option to go buy some metal drill bits?

bluechair84

Got it, only took about 70mins of hacksawing, hammering and shouting.

andrewjoseph

it was the hammer that did the trick, best tool in the box.

bluechair84

If in doubt, bigger hammer...

jfry94

use a slightly bigger torx bang it into the rounded hex usally does the job

bluechair84

Yeah I tried that, couldn't get a 6 into the 5. Had to file in some grooves and use a flat head to get it out. Massive damage to the crank done in doing so, but it was shagged at the splines anyway.

The Rookie

Next time use an easy out!

bluechair84

What's this? I thought the easy way out never existed...

The Rookie

An easy out is a hardened left hand screwthread tool, you drill a hole in the centre of the 'problem' bolt and screw the easy out into it, eventually it's tapered thread won't go in any further and it turns and undoes the bolt.........or snaps (the problem with it being hardened) if you are not a little careful.

First yahoo hit as a description
http://www.brokentap.com/easy-outs.html

stubs

Easy Outs are not a good idea I have never known them to work unless you have a pillar drill and get the hole dead centre. If the Easy Out breaks you have to burn it out with a spark eroder nothing will drill an Easy Out.

If the crank is going to be knackered anyway then use a Dremel to cut grooves in the Aluminium as many as you can radially round the offending bolt hole. Then pick up big lump hammer wrap a towel round the frame and WHACK the pedal end the crank should break and you will be able to remove it with a couple more blows.

The Rookie

Larger easy out's I've always found to be OK, its the smaller ones where the surface hardening forms more of the material that snap easily, the answer is to be gentle, never had anything over a 4mm snap on me....if the crank is scrap anyway, then yes, destroy it, if it's not it's an expensive way to remove a bolt!