Originally Posted by
Velognome
+1, this is better than grinding I think, less chance of marking up the crank. Plus the bend looks to originates below the crank surface, so you'de only end up with a short bent cotter. A few blows from a drift punch will usually snap it off below the crank surface, than you can begin with the press again. If you resort to wacking it with a hammer, be sure to back it up with something so that the BB doesn't take the force of the blow.
I had this happen recently as well, and ended up just taking the hacksaw (I need to get a grinder!) to what was sticking out of the hole - left about 1mm between the end of the cotter and the crank arm, worked really well because they are super soft material. That gave a nice flat spot on the end of the cotter - which provided a nice surface to hit it with a punch a few times, then break out the drill. I ended up drilling to 5/16 before getting the pin to budge - but mine had also been in there since 1972 (or at least I am pretty sure it was anyway).