I had to remove cottered cranks from an old Raleigh “Scorpio” I’m building up for my girlfriend… the left side pin popped out easily, the ride side was so freaking stuck, I had to purchase an angle grinder to cut through the bottom bracket spindle. It sucks, they were original Raleigh cranks, but there was no way I was getting it off easy.
Just removed some cranks from a shitty old road bike - it was free and the cranks are those ones where the two chainrings are sort of the same piece of metal… I have a nice park tools crank puller - got the left off fine, threaded the right. Was pissed for a few minutes. Put the left back on and rode around for about 30 mins… no luck. Took the left off, undid the bottom bracket and took the right off still attached to the axle - easy. I’m going to have a go bashing the axle out but then it’s to the bin.
I was told by a wise old bike mechanic once that you put zinc (like Andy Symonds) on the spindle before you install the cranks. The reason that arms get stuck on it the chemical reaction between the steel spindle and the arms fuses the two materials together. I’ve done it ever since and have never had a problem. I also use a crank puller so maybe the zinc is just a placebo.