How to remove press fit steel pin from aluminum?
08-19-19, 04:16 PM
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How to remove press fit steel pin from aluminum?
I've got a Huret Jubilee front derailleur with a cracked hinge. @rustystrings61 was kind enough to donate a rusty copy so I could see if a hinge swap would be possible. I removed the bits which screw on to the main components, but am a bit stuck with what I believe to be a press fit pin which joins the hinge to the body. Can I just heat up the aluminum to get the steel pin out? If so, how hot?
08-19-19, 04:25 PM
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Try an arbor press without heat first.
If a no go, your standard propane torch should suffice.
If a no go, your standard propane torch should suffice.
08-19-19, 04:44 PM
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couple thoughts.
1) look very carefully for any cross pins that may have been used to lock that pin in.
2) The fact that the the coeff of expansion of Al is more than that of steel is your friend, the body will expand more than the pin with a given temp rise.
3) I doubt the pin was put in with loctite or similar but you never know, heat will take care of that.
4) If you use heat be careful how hot, both for the alloy body and any springs that may still be in there. If there is no plastic (bushings etc) in it I would tend to put in in a toaster oven @ 450 f for 1/2 hour and try it, that temp will not hurt springs.
5) If there are any springs or plastic in there I wouldn't go near it with a torch.
1) look very carefully for any cross pins that may have been used to lock that pin in.
2) The fact that the the coeff of expansion of Al is more than that of steel is your friend, the body will expand more than the pin with a given temp rise.
3) I doubt the pin was put in with loctite or similar but you never know, heat will take care of that.
4) If you use heat be careful how hot, both for the alloy body and any springs that may still be in there. If there is no plastic (bushings etc) in it I would tend to put in in a toaster oven @ 450 f for 1/2 hour and try it, that temp will not hurt springs.
5) If there are any springs or plastic in there I wouldn't go near it with a torch.
08-19-19, 04:59 PM
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If you don't have a press, you might be able to improvise with a vise. In any case you will need pin of slightly smaller diameter to push on the pivot pin, and a tube or pipe of appropriate ID to receive the pivot pin as it pushes out. I would actually recommend supporting the assembly on such a piece of pipe, and tapping out the pivot pin with a pin punch of slightly smaller diameter than the pivot pin. I suggest soaking the assembly in penetrating oil beforehand, and moderate application of heat for good measure, or if initial attempt does not result in movement with reasonable tapping force.
08-19-19, 05:44 PM
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If you don't have a press, you might be able to improvise with a vise. In any case you will need pin of slightly smaller diameter to push on the pivot pin, and a tube or pipe of appropriate ID to receive the pivot pin as it pushes out. I would actually recommend supporting the assembly on such a piece of pipe, and tapping out the pivot pin with a pin punch of slightly smaller diameter than the pivot pin. I suggest soaking the assembly in penetrating oil beforehand, and moderate application of heat for good measure, or if initial attempt does not result in movement with reasonable tapping force.
08-19-19, 07:35 PM
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The small end of that pin looks like it was peened. I'd suggest some mild grinding/Dremel work on that end before doing anything.
You may find once the peening is removed it just...falls out.
You may find once the peening is removed it just...falls out.
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08-20-19, 09:13 PM
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Some press fit RD pivot pins have fine splines on them for a friction fit.
You remove those with a press or a drift.......carefully....
You remove those with a press or a drift.......carefully....
