Cotter pin press

If you have some thread poking out, use the nut to draw it fully in position. Years ago we just tapped them through with a soft hammer until a nut could be fitted. 🤷‍♂️
 
If you have a bench top vice then you already have a cotter pin press. All you need is a strong bit of metal with a hole in it for the pin to drop into that you place over the pin and sandwich in the vice with the crank so that the threaded portion can be pushed through.
Alternatively as said before frequent tapping with a small hammer and penetrating oil often works. To get started unscrew the nut to end of thread but don't remove, the nut will help prevent the threaded portion of the pin from deforming as you tap it. Don't welly it really hard just lots of tapping with the oil and maybe some alternating boiling water, cold water to cause some metal expansion and contraction.
 
I read this with some amusement. I no longer use or have cottered chainsets, but back in the day, it was a case of bang em in hard, no rubber mallet or wood to soften the blow, it was real Fred Dibnah stuff. Hit hard and screw on the nut.

Not that I think I was right, it's just how I did it
 
The real secret with the hammer method is to support the BB axle so that the force of the hammer blow is not absorbed by the frame. wheels and tyres flexing. With the crank horizontal we would hold a big lump hammer tight under the crank in line with the BB axle (avoiding the pin of course) then give the end of the pin a smack with a lighter hammer. If we were driving a pin out we would leave the nut in place but just unscrew it by a couple of turns - that gave a bigger target to hit and protected the pin threads. Once the pin had moved the nut was taken off and the pin tapped out.
And we had a VAR 07 cotter pin press hanging on the tool board - a tool with which we had little success except for when we had to remove cranks from a brand new bike.
 
If you have some thread poking out, use the nut to draw it fully in position. Years ago we just tapped them through with a soft hammer until a nut could be fitted. 🤷‍♂️
That doesn't work well, as cotter pins are deliberately soft steel. They have to be forced in from the plain end, and the nut is just for retention. If you try to seat the pin properly by tightening the nut, it will strip.

Cotter presses are almost unobtanium but a large bench vice and a suitably-sized socket can usually do it.

If you use a hammer to remove them, loosen the nut but do not remove it. It stops the pin mushrooming, which can lead to a world of pain.
 
After reading this I reckon I will start having nightmares again, dreaming about cotter pins, big hammers and steel cranks.

AAARRRGGHHHH!!
 
As a kids we used bang 7 bells out of them with a lump hammer, to get them in or out! Even road around with no nut fitted at times because we foobarred the threaded bit. We eventually learned how to do it with a little more finesse until we found square tapers 🤣
 
As a kids we used bang 7 bells out of them with a lump hammer, to get them in or out! Even road around with no nut fitted at times because we foobarred the threaded bit. We eventually learned how to do it with a little more finesse until we found square tapers 🤣
likewise. The good ol days when repairs could be done in Dads shed and replacements cost pennies
 
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