Mangled crank bolt removal

[markoc]

I picked up a P7 with some nice bits.

Previous owner appears to have been somewhat heavy handed trying to remove a crank bolt. It’s completely rounded and looks to have something stuck in it



Any ideas on how to get this bugger out.

 

[Lucidone]

Don't think there's any easy answers to that one.

Either drilling (if nothing super hard already embedded) or possibly welding something in/on you can turn/get a tool on (guessing it's going to be pretty solid though!)

Spark erosion if you're feeling posh.

 

[royaloaker]

start with a 1/16" carbide drill bit and work your way larger with lots of lube on the tip.looks very doable with the right drill bits.

 

[markoc]

start with a 1/16" carbide drill bit and work your way larger with lots of lube on the tip.looks very doable with the right drill bits.

Thanks - What am I trying to achieve, drill the whole bolt out or get a purchase?

Cranks are Middleburn RS1 and the BB is a shimano so the BB can be sacrificed

 

[ishaw]

I'm suffering the same challenge with an xtr crank. BB I'd not sacrificial. My goal is to get a hole drilled in the bolt, and use an easy out to unscrew it (left threaded tool). The bolt in mine is a very hard metal and choosing to be stubborn, but I will win the battle.

 

[bikeworkshop]

If it's hardened steel, you might be able to weld a nut on the end without zapping the crank.
Possibly fitting an m10 nut and welding it on around the inside.

The energy involved often breaks the bond.

 

[ishaw]

I'd love to do something like that, or even just a bit of bent steel to use as a handle and unwind the bolt. Sadly don't have access to a welder.

 

[Frankenorange]

How about the type of bolt extractor that will grip the outer diameter of that bolt head?

Should be enough clearance between the tool and the threads in the arm.

 

[royaloaker]

drill just under the size of the bolt threads.you don't have to touch the BB spindle. grab the remains of the head with visegrips and it should back out easily.

 

[bikeworkshop]

A little mig is only a hundred quid second hand - it gives you superhuman powers.

Most shimano bbs will come out drive side.
If you take the lh crank off, remove the lh cup, then see if you can get a punch or similar (maybe 2 flat head screwdrivers and a tommybar) onto the extraction teeth on the drive side, you may be able to get the bb out with the rh crank still attached.
We've done this many times, due a variety of reasons, but often need an extra pair of hands.


...Then you can take it to someone who can get the bolt out with a press drill or mig welder or whatever.