Drago
Legendary Member
- Location
- Suburban Poshshire
I use a big old car ball joint splitter.
Removing ancient cotter pins
- Thread starter swee'pea99
- Start date
Page may contain affiliate links. Please see terms for details.
OP
OP
swee'pea99
Legendary Member
[QUOTE 5020996, member: 45"]I bought a new, decent bit to do the work.[/QUOTE]
Sorry, should've thought to ask - what size bit did you use? (And, come to think of it, which end did you go in?)
Sorry, should've thought to ask - what size bit did you use? (And, come to think of it, which end did you go in?)
OP
OP
swee'pea99
Legendary Member
[QUOTE 5021086, member: 45"]I started small then got bigger. I cut the threaded end flat and went in that way. It might be the wrong end, but I'm from the Fred Dibnah school of engineering - just get stuck in.[/QUOTE]
Thanks. Top tips.
Thanks. Top tips.
subaqua
What’s the point
- Location
- Leytonstone
Hot air gun better than a hairdryer.
if you know how to do it with a blowtorch you can but its really easy to make things a whole lot worse
OP
OP
swee'pea99
Legendary Member
Thanks. 'cept if you don't have one, eh?
As for blowtorches, me & the blowtorch have never been introduced, and I have a feeling it's probably best to keep it that way.
subaqua
What’s the point
- Location
- Leytonstone
You could try it might take a while and be a lot gentler than you needThanks. 'cept if you don't have one, eh?
As for blowtorches, me & the blowtorch have never been introduced, and I have a feeling it's probably best to keep it that way.
A little creme brulee butane torch is easy to use heating the pedal alone rather than the pedal, the crank, the axle and burning all the paint off the bottom bracket with a proper plumber's blowlamp. I would always use heat to assist the techniques below and add penetrating fluid to the hot parts. Buy the torch; there will be other stuck nuts/bolts in your future.
I bought new cotters for my 1949 MG kingpins; was puzzled that they had threads on BOTH ends, the tapping-in end fitted with a domed nut (see pic).
I think the genius idea is you can just removed the domed nut, add a stack of big washers and then tighten the domed nut back to draw the cotter pin back out; so the cotter pin had its own built in cotter-pin extractor.
I shall use this principle next time I get a stuck cycle cotter; I'll drill the cotter (hammering-end NOT threaded end) part way using (say) a 4.2mm drill which is correct to tap an M5 thread inside the cotter. I can then pop the stack of washers, or a socket/pipe-offcut and a washer over and draw the pin out with an M5 bolt. I suggest M5 assuming a 1/4" (~6mm) cotter. A set of 3 M5 taps is about £5.
All hammering on the cotter pin's original threaded end tends to swell the pin and make it stick harder. My favourite technique in the past has been to drill a hole and then drift the cotter-pin out with a parallel pin punch in the drilling; I file the end of the damaged cotter threads flat to allow me to, very carefully dot-punch the exact centre then drill a good long way through the pin, usually drilling about 4.5mm to take a 4mm pin-punch. With care a 4.5mm drill in a 6mm cotter-pin shouldn't wander and damage the pedal-crank. The drilling heat will help release the pin, the 4.5mm hole will allow the metal of the pin to relax a little away from the crank and, if you drilled the cotter right through the axle, the pin punch impacts will be PULLING the taper part of the pin through allowing it to shrink, rather than swell and jam more. I have tried using a cut-off nail as the pin punch; crap! Get a cheap pin punch.
I bought new cotters for my 1949 MG kingpins; was puzzled that they had threads on BOTH ends, the tapping-in end fitted with a domed nut (see pic).
I think the genius idea is you can just removed the domed nut, add a stack of big washers and then tighten the domed nut back to draw the cotter pin back out; so the cotter pin had its own built in cotter-pin extractor.
I shall use this principle next time I get a stuck cycle cotter; I'll drill the cotter (hammering-end NOT threaded end) part way using (say) a 4.2mm drill which is correct to tap an M5 thread inside the cotter. I can then pop the stack of washers, or a socket/pipe-offcut and a washer over and draw the pin out with an M5 bolt. I suggest M5 assuming a 1/4" (~6mm) cotter. A set of 3 M5 taps is about £5.
All hammering on the cotter pin's original threaded end tends to swell the pin and make it stick harder. My favourite technique in the past has been to drill a hole and then drift the cotter-pin out with a parallel pin punch in the drilling; I file the end of the damaged cotter threads flat to allow me to, very carefully dot-punch the exact centre then drill a good long way through the pin, usually drilling about 4.5mm to take a 4mm pin-punch. With care a 4.5mm drill in a 6mm cotter-pin shouldn't wander and damage the pedal-crank. The drilling heat will help release the pin, the 4.5mm hole will allow the metal of the pin to relax a little away from the crank and, if you drilled the cotter right through the axle, the pin punch impacts will be PULLING the taper part of the pin through allowing it to shrink, rather than swell and jam more. I have tried using a cut-off nail as the pin punch; crap! Get a cheap pin punch.
Chris S
Legendary Member
- Location
- Birmingham
craigwend
Grimpeur des terrains plats
Ajax Bay
Guru
- Location
- East Devon
Great post! If the Welsh language can be resurrected, so can cottered cranks.
ColinJ
Puzzle game procrastinator!
- Location
- Todmorden - Yorks/Lancs border
If only they could do that for youthful health and fitness!
Dogtrousers
Kilometre nibbler
@swee'pea99 did you get them out in the end?
T4tomo
Legendary Member
which is the most annoying though?
antnee
Guru
- Location
- Weston Super mud, North Somerset
Yes try the heating solution, if not I'd defiantly get the drill ready but go carefully.
Dogtrousers
Kilometre nibbler
My advice is to leave it for five years. You never know it might just drop out of its own accord.
