Been a bit of a numpty with my chainring.

Rounded the bolt so tried to drill them out. Worked fine on the outer and middle chainring but the inner ring I really seem to have messed up.

Tried to drill it out and I now have a bolt that I have drilled a hole right through the centre. Maybe 1mm or less from the thread. Don’t think a screw extractor would work now but couldn’t find one at local diy stores anyway.

I am really not wanting to knacker the thread on the crank as an impending baby means forking out for new crank is really not needed

Any ideas to rescue my drive side crank arm?

picture?

1 x 9

Junior hacksaw blade and cut through whats left of the bolt then a center punch and collapse the bolt inwards near the cut. It’ll unscrew dead easy when theres no pressure on it.

On looking it is pretty much at the thread. 😳

After seeing the pics just use a bigger drill bit and take the head off.
Again once the tensions gone they’ll come out without any bother.

Junior hacksaw blade and cut through whats left of the bolt

You mean longways then push it inwards?

Are the spiders available separate from the arms? Worse case scenario thinking here.

edit: just seen your next post. so remove the head then the inner will be easier to unthread? Will try that tomorrow.

go with singlespeedstu’s suggestion first. Use the hacksaw the create a slit so you can use a decent sized flat screw driver to undo. If that fails then try and drill the head off.

edit: just seen your next post. so remove the head then the inner will be easier to unthread?

Yep It’ll come out a POP after the head and tension have been removed.

cool cheer guys. Will try tomorrow and report back.

These bolts seem to be made of cheese as I had the right tool, snug fit etc etc then on turning they just instantly rounded.

Also just thought if I remove the head I can remove the inner ring then push the remains inwards to collapse what is left.

I knew this wouldn’t go smoothly 🙁

Failed and admitted defeat. Took the head off and the bolts seem welded in.

Decided to take to shop to get them properly drilled and rethreaded. 😥