Re-pivoting a wheel

[luiazazrambo]

Hi *,

The mainspring of this clock was broken for the chime train, I agreed to replace it even though I stopped working on clocks before I actually could develop a knowledge regarding them and moved to watches as they are smaller the tools are smaller and cleaning them is not such a dirty job. (even though I like clocks better) I immediately noticed that there is a problem with one of the wheel, unfortunately its pivot is broken. How do I go about this? I understand I would need to drill a hole at least as deep as 3x the diameter of the pivot but as I never done this before and this is not my clock I would not really try it unless there is a good chance to succeed which I actually doubt. Could someone tell me what to do here, what video to watch, what book to read what are the major NONOs or anything you think is worth to say here? What is the hardness here? Is any kind of heat treatment involved? I have an unimat 3.

https://photos.app.goo.gl/ypwjfqnyLZ8j4jXW7

Best regards,

Lui

[RichardHarris123]

Please wait for someone with more experience than me to reply but here's my take.  The shaft ( terminology) needs replacing, the shaft is slanted, not running true, why? 

[luiazazrambo]

Thanks shaft it is!  The shaft is broken off and is in the green jelly which once was the lubrication.

[tomh207]

I would recommend looking at @Dell YouTube channel, no nonsense practical stuff there. He uses a pultra 10mm lathe so just a little smaller than your uni at 3 I think.

 

he has a few of these or maybe he will be able to recommend something.

 

Tom (not a clock guy, but listening to @OldHippy, @Dell and @MikeEll)

 

 

[AndyGSi]

Can you not remove the wheels and replace the complete shaft?

[MikeEll]

Are you sure it’s the pivot that’s broken off?  From the picture it looks like the end of the wheel arbour has sheared off.  If you gently remove the broken piece from the wheel bridge and show a picture, I’m expecting to see a broken piece of the arbour with the pivot itself still on the end of it.  

If so then it’s not as simple as repivoting as there will be too much end shake on the resulting wheel arbour.  It would need the arbour repairing and a pivot turned to the end of it, or adding with some blue steel.

Edited March 29 by MikeEll

[watchweasol]

There are two ways to repair the clock. First depending on the maker obtain another hammer drive wheel complete.  Or. Re pivot the original, bearing in mind these pivots and pinions are as hard as glass. You would need to anneal the broken end then fir up in the lathe and drill the pinion fitting a new pivot ( friction) tight with either loctite or superglue. The new pivot will need hardening , burnishing and polishing. But it looks suspiciously as @MikeEll said that the top of the arbour has broken off leaving thr pivot and arbour stub in the cock.  How it manage£ this is anyone’s guess but it’s rather odd the arbour gave out before the pivot which is considerably weaker.  Is there a logo or stamp on the back plate.

[luiazazrambo]

[watchweasol]

French clock design but most likley European , zGerman. Any name on the dial at all.

[luiazazrambo]

I wasnt sure I left it in the green jelly in the cock. Clever you! 

 

There us not much light for a good photo but I quickly placed the movement back temporarily in its case for a portrait. 

Barnett & Scott - Hull

[oldhippy]

It is my bedtime so I'll add my view tomorrow. I will just say the movement is certainly French. Us old buggers need our sleep. 

Edited March 30 by oldhippy

[Dell]

That arbor is repairable the main problem I can see is holding it , the pinion would need annealing before drilling.

Forgot to say heat shrink new bit in killing two birds with one stone good friction fit & hardening.

Edited March 30 by Dell

[oldhippy]

You certainly won't find a replacement, you might think many look the same but I can tell you they are not. As Dell Has said it can be repaired but holding it is a  different matter. The only way I can think of at the moment is to remove the wheel then you have a way of holding the the other in a chuck and proceed what Dell has said.    

Edited March 30 by oldhippy

[luiazazrambo]

Thank you all for sharing your knowledge and thoughts. I am very experienced in breaking things and this job seems just like the one that would end in disaster should I try.  

So I would need to

1., anneal the pinion 2., drill it 3., make a new bit 4., heat treat the new bit 5., Push the new bit in while hot? 6., size and polish the new pivot? 7., what about the pinion ? does it need heat treating after annealing it? When?

Plus you need to remove the wheel before u start and put it back when you finished. I assume the wheel is soldered on by the look of it.

The pivot hole shows some ovalness looking at it from the bottom by the way. And out of curiosity what was the green glue originally? I met it many times, but I dont know what sort of lubrication/oil was used. Green comes from the oxidation?

I normally would carry on regardless how difficult the job might seem, but again this clock is not mine. Hmm.

Ahh and to add to the story the new owner of this clock tried to wind it up when the mainspring for the chime train has broken, so it is a recent damage the clock received. I assume the damage to the shaft/pivot happened at the same time when the mainspring shattered/power released?

[oldhippy]

That is a bush so it has already been re-bushed and not very well. Yes the wheel is soldered. The green would be old oil or grease. The spring certainly can cause damage like that, it is more popular when springs break to cause damage teeth or even bend wheels out of shape.  The repair really is for someone who has plenty of experience and not for the faint hearted . You have been unlucky with this one my friend. 

[Dell]

  On 3/30/2025 at 9:58 AM, luiazazrambo said:

So I would need to

1., anneal the pinion 2., drill it 3., make a new bit 4., heat treat the new bit 5., Push the new bit in while hot? 6., size and polish the new pivot? 7., what about the pinion ? does it need heat treating after annealing it? When?

 

 

 

 

 

 

Expand  

You wouldn’t need to heat the new part only the pinion too expand it enough to press fit the new bit in & quench it before it cools to much that will harden the pinion & if you make the part out of silver steel it it wouldn’t need hardening.

If you do decide to tackle it measure position of wheel before removing then heat the pinion to just starting to go red then let cool naturally ( it will be annealed but keep drill cutting or it will work harden),preferably use a carbide drill bit but be careful they are brittle ( small pecks ), before fitting new bit heat pinion to same press fit new bit a quench , when fitting wheel it can be done in the lathe melt solder fit wheel run lathe apply heat to allow solder to flow touch wheel with side of peg wood to straighten wheel let cool naturally, re bush bridge to suit.

i hope I am not trying to teach grandmother to suck eggs, just ignore if I am.

Dell

[luiazazrambo]

  On 3/30/2025 at 11:41 AM, Dell said:

i hope I am not trying to teach grandmother to suck eggs, just ignore if I am.

Dell

Expand  

We are all living in a pond but you are a fish while i am a mole. I struggle with English as I am Hungarian but when it comes to watchmaker English it gets even more difficult for me. When I try to read something from George Daniels sometime it takes me a day or two to understand the meaning of a sentence or page. It is all down to the fact that as him and you feel natural in this pond but I am a bit new to it and a bit of strange to have water in my lungs.  Now I am not sure how a grandma sucks on eggs either.  I am going to re-read your post probably a hundred time and going to process it slowly. What is the meaning of "small pecks"? Going slowly just a bit at the time? I subscribed.

Edited March 30 by luiazazrambo

[Dell]

  On 3/30/2025 at 6:07 PM, luiazazrambo said:

We are all living in a pond but you are a fish while i am a mole. I struggle with English as I am Hungarian but when it comes to watchmaker English it gets even more difficult for me. When I try to read something from George Daniels sometime it takes me a day or two to understand the meaning of a sentence or page. It is all down to the fact that as him and you feel natural in this pond but I am a bit new to it and a bit of strange to have water in my lungs.  Now I am not sure how a grandma sucks on eggs either.  I am going to re-read your post probably a hundred time and going to process it slowly. What is the meaning of "small pecks"? Going slowly just a bit at the time? I subscribed.

Expand  

Teaching grandmother to suck eggs is an English saying meaning hope I am not trying to teach you something that you already know, small pecks is drill a bit pull out to clear swarf drill a bit and so no.

We all have to learn Dell

Edited March 30 by Dell

[rjenkinsgb]

Can you measure the diameter of the shaft and its length over the tips of the pivots? 

(Or distance between the main plates + thickness of a plate, to give the length between pivots?)

As OldHippy says, the chance of finding a complete replacement shaft & wheel etc. is next to zero - but just a suitable shaft from a scrap parts collection has a bit better odds?

[luiazazrambo]

  On 3/30/2025 at 6:37 PM, Dell said:

Teaching grandmother to suck eggs is an English saying meaning hope I am not trying to teach you something that you already know

Expand  

I thought as much but when you first read it you have wild pictures in your head.  Could these be used for the new bit? What steel is this? What does the blue pivot steel mean?

[oldhippy]

It is quenched and tempered. 

[Dell]

The holder the blued steel is in looks like a gun shell, and it looks old so probably good quality blue steel, some of the new stuff is rubbish.

Dell

This video maybe of help to you to give you an idea of what’s involved.

https://youtu.be/-eYvYYc-8dc?si=K_6dU2PifHeuT7An

needless to say it’s not how I would do it or suggest you do it but it’s just to give you an idea of what’s involved.

Edited April 4 by Dell

[luiazazrambo]

It seems like the shaft was weakened by a cut, probably this was the reason why it broke here.

Considering that the missing bit has the following parameters what would you suggest for the drill/hole size for the new bit?

[Dell]

I would suggest for the drill  use a size 58=1.07mm then turn the pivot to the size you need after fitting the part that way you can be certain that the pivot is concentric with the rest of the arbor.

Dell

[luiazazrambo]

Thanks, with this you answered my next question as when to turn the pivot, I assume it also helps to do the length/adjust the end shake with this as you cannot be 100% certain how deep exactly you can push the new bit down.