Stuck pin in truing caliper

[omegahunter]

Hi all. 

I messed up and broke the pivot of a fourth wheel I was trying to true up.  The pin is lodged in there and I can't remove it.  There is a hole in the stump to facilitate cleaning and removal. The truing caliper is what I think is called a lyre type.  Any ideas on what I can do?

 

 

 

 

 

[MechanicMike]

pics please

[omegahunter]

Please excuse the dust and debris.  I didn't realize how dirty the tool is.   Broken pivot in the top stump

Edited April 14, 2023 by omegahunter
spelling

[Endeavor]

Of course it's always best to reverse the part out, and you are 100% correct in saying that the hole is there to facilitate cleaning and removal of broken parts. So, that's where you should concentrate on. There are still a few unknowns which only you can see/know, like is there anything of the pivot visible in the cleaning hole, how much pivot is in the stump, with how much force was it pushed into it and what's the shape of it; conical or cylindrical. The shape and diameter of the part determines whether, as very last resort, you can push the part further in and out the cleaning hole, but that should only be attempted if everything else has failed and there is nothing more to loose.

But your main focus should be to reversing out with any idea you may come up with. Perhaps a sharpened / pointed steel paperclip-tip, with the tip bend to an angle (say anywhere between 60 - 90 degrees) so you can access the pivot hole from the cleaning hole? A screwdriver as an aid to increase the down-force on the paper-clip?

Needless to say, you have to get the stump out of the tool to work on it.

Perhaps others do have other idea's which may help you?

Suc6

 

 

Edited April 14, 2023 by Endeavor

[omegahunter]

Thanks endeavor I will fashion something and see if I can push it out from the hole.  I just wanted to see what others would do or if there is some special tool used.

[Endeavor]

Not that I'm aware of, but people are creative

I think that this truing-tool is mostly used for truing balance-wheels. I'm far from knowledgeable regarding truing, but one would assume that a wobble in the balance wheel has a far greater effect than a 4th wheel. After changing out a balance-staff the balance wheel can be out of true, but for a 4th wheel to be out of true, something more drastic must have happened

Anyway, suc6 with the "unplugging"

Edited April 15, 2023 by Endeavor

[praezis]

If the broken pin is long enough to reach into the hole, push it out from the hole with a screwdriver.

Else push it to the hole and remove from there (if too long, break it in the hole).

Frank

[Endeavor]

11 hours ago, praezis said:

If the broken pin is long enough to reach into the hole, push it out from the hole with a screwdriver.

Else push it to the hole and remove from there (if too long, break it in the hole).

Frank

Just for my own education; what is the difference between what I suggested (above) and what you are suggesting?

Edited April 15, 2023 by Endeavor

[Neverenoughwatches]

4 hours ago, Endeavor said:

Not that I'm aware of, but people are creative

I think that this truing-tool is mostly used for truing balance-wheels. I'm far from knowledgeable regarding truing, but one would assume that a wobble in the balance wheel has a far greater effect than a 4th wheel. After changing out a balance-staff the balance wheel can be out of true, but for a 4th wheel to be out of true, something more drastic must have happened

Anyway, suc6 with the "unplugging"

Calipers often have two types of end pins, a set for poising and a set for truing. The truing pins have a conical recess at their end that holds the cone of a pivot, rather than the pivot itself which wouldn't withstand the pressures of truing. The side hole i assume also allows the pivot to pass though untouched while being trued. Poising pins just have a hole or a spring loaded jewel bearing in the center for the pivots to rest in. 

[omegahunter]

15 hours ago, Endeavor said:

Not that I'm aware of, but people are creative

I think that this truing-tool is mostly used for truing balance-wheels. I'm far from knowledgeable regarding truing, but one would assume that a wobble in the balance wheel has a far greater effect than a 4th wheel. After changing out a balance-staff the balance wheel can be out of true, but for a 4th wheel to be out of true, something more drastic must have happened

Anyway, suc6 with the "unplugging"

The something more drastic is me being clumsy .  Anyway I'll try to make a pin with a little bend at the end and see if I can push it out.  The pivot is not visible through the hole.  I really don't want to push from the front because I'm scared I'll mangle it.