Awkward bolts!

[binrotheheretic]

Been trying to remove the cranks in order to replace the bottom bracket, after much effort I managed to remove one side, however despite being careful the thread inside the other one has 'rounded-out', meaning the allen key just spins round. There's not much room to drill a bigger hole or anything like that, but I can't figure out how to remove the darn thing now. Any ideas?
Cheers

[GeorgeET]

Photos would be a big help here.

I think you are trying to remove the crank bolt , that's the only allen head I can visualize.

[binrotheheretic]

Yes that's right - I'll aim to post some photos shortly

[binrotheheretic]

[attachment=4256][attachment=4257]

[GeorgeET]

Cannot tell too much from photos but at least we know what bolt you are talking about. Spray some good penetrating oil in there , do not know where you are so do not know brands, put bicycle on side and let the bolt soak overnight.
There are abrasive compounds you can put into the bolt head and that would help the allen wrench grab. Otherwise you can use a small sharp cold chisel maybe even a screwdriver that fits tightly and need to be forced in with taps from hammer than grab that with a wrench or pliers and try that. You do have a crank puller?
Once the bolt is mangled its pretty much a destracto job to get it out.

You could also drill the head off if the above fails. Just drill straight in till the head can be collapsed. You can use progressively bigger drill bits.Not fun...

[bobtravers]

Use a big bolt extractor... Use a Vise-Grip with it...

http://m4.uxcell.com/photo_new/20080929/c/ux_a08092900ux0077_ux_c.jpg

[GeorgeET]

(06-17-2013, 07:55 PM)bobtravers Wrote:  Use a big bolt extractor... Use a Vise-Grip with it...

http://m4.uxcell.com/photo_new/20080929/c/ux_a08092900ux0077_ux_c.jpg

Yes easy out will work too, if you have a set . You first need to drill a center hole screw easy out in clockwise and unscrew bolt CCW. They are very hard therefore easy to break . No side forces.

Since you have the other bolt out that would give you an idea of how big an easy out you need. Smaller than the bolt.