Universal Geneve 138

[mikecj]

Happy New Year Y'all,

I am working on an Universal Geneve 138 movement. Had to replace the balance due to a damaged hairspring. Now it appears the balance staff is too long? When I install the balance without the bridge screw, it oscillates perfectly. When I install the balance cock screw and begin to tighten all rotation stops. ! see one of three solutions.

1. Adjust the upper incabloc setting. (I have a horia tool) I don't if this possible since the setting is held in place with a U-shaped clip. See the pictures.

2. Adjust the lower incabloc setting. I don't know if this is possible since the setting is held in place with a screw. I'm afraid any pressure on the lower jewel hole will bend the brass setting.

3. Place a shim between the balance cock and the main plate to raise the upper jewel.

Any advice would be appreciate.

thank you,

MikeCJ

 

[AndyGSi]

1 hour ago, mikecj said:

Had to replace the balance due to a damaged hairspring.

Are you sure you got the correct complete balance?

Edit

Photos of the new balance may help.

Edited January 1 by AndyGSi

[Knebo]

You said that your replaced the balance because of a damaged hairspring. Is the balance wheel and pivots in good shape? 

If so, you could take the hairspring from the replacement balance and put it back on the original balance. 

But if you try this, be extra careful. I once had a case where the replacement hairspring wasn't actually 100% correct and the collet was smaller and wouldn't fit on the original balance staff. Almost broke the collet. 

[AndyGSi]

11 minutes ago, Knebo said:

If so, you could take the hairspring from the replacement balance and put it back on the original balance.

That's working on the principal that it's the correct one to start with as there's multiple options for this movement.

[Knebo]

Just now, AndyGSi said:

That's working on the principal that it's the correct one to start with as there's multiple options for this movement.

That's very true. I assumed that the "original" balance would at least spin freely when the balance cock is screwed down. 

[AndyGSi]

39 minutes ago, Knebo said:

That's very true. I assumed that the "original" balance would at least spin freely when the balance cock is screwed down. 

It depends if they've got the flat or berguet spring on the new balance.

[mikecj]

Thanks for the replies. To answer your questions, the hair spring had a nasty bend and the balance staff had a broken pivot. Thus it was easier to obtain a balance complete than the individual parts. The replacement came from a  Universal Geneva 139 which was supposed to be compatible with the 138.

[Klassiker]

How do the dimensions of the old and new balance staffs compare? I don't think you can adjust the Incabloc positions.

[eccentric59]

Are you sure you have the cap jewels right-side (domed side) up? Does the balance spin freely with the cock tightened but the upper jewel removed?

[AndyGSi]

1 hour ago, mikecj said:

The replacement came from a  Universal Geneva 139 which was supposed to be compatible with the 138.

Was it an Incabloc version of the 139 as the non version balance staff is slightly longer.

[Nucejoe]

On 1/1/2025 at 11:49 PM, Knebo said:

You said that your replaced the balance because of a damaged hairspring. Is the balance wheel and pivots in good shape? 

If so, you could take the hairspring from the replacement balance and put it back on the original balance. 

 You might call    (old balance and new hairspring matching)    a miracle. 

Every balance wheel will oscilate isochronically only with a certain length of hairspring.

 

 

Edited January 3 by Nucejoe
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[Klassiker]

14 minutes ago, Nucejoe said:

You might call, old balance and new hairspring matching  a miracle.

Only if it works!

[Nucejoe]

First you should check if the setting on mainplate is movable.

Then shim the cock such that you can stop the balance by tightening cock screw by less that 90 degrees on one hand and 

free the balance to run full swing ( on the other hand)  by loosening cock screw back by same 90 degrees

That is loosen and tightening the screw , stops and sets free the balance to oscilate. 

Then you should check if all looks good at the this height , where the balance oscilate full swing, check;

Fork horn not rub on roller table. 

Balance rim stand at least .5mm above fork cock.

Hairspring at least 1mm away from balance spokes and underside of the cock. You don't want any part rub.

Next put the watch on timegrapher, if all looks good in at least three positions !  Undo all.

Go to the setting on mainplate to move it for adjusting without the shim.

Shim and gouging is ugly and folks tend to  frowned upon them. 

Rgds

Edited January 2 by Nucejoe

[Neverenoughwatches]

23 hours ago, mikecj said:

I  see one of three solutions.

1. Adjust the upper incabloc setting. (I have a horia tool) I don't if this possible since the setting is held in place with a U-shaped clip. See the pictures.

2. Adjust the lower incabloc setting. I don't know if this is possible since the setting is held in place with a screw. I'm afraid any pressure on the lower jewel hole will bend the brass setting.

 

These are only solutions if the finished balance position agrees with how it interacts with the fork. Their heights need to coincide.

3 minutes ago, Nucejoe said:

First you should check if the setting on mainplate is movable.

Then shim the cock such that you can stop the balance by tightening cock screw by less that 90 degrees on one hand and 

free the balance to run full swing ( on the other hand)  by loosening cock screw back by same 90 degrees

That is loosen and tightening the screw , stops and sets free the balance to oscilate. 

Then you should check if all looks good at the this height , where the balance oscilate full swing, check;

Fork horn not rub on roller table. 

Balance rim stand at least .5mm above fork cock.

Hairspring at least 1mm away from balance spokes and underside of the cock. You don't want any part rub.

Next put the watch on timegrapher, if all looks good in at least three positions !  Undo all.

Go to the setting on mainplate to move it for adjusting without the shim.

Shim and gouging is ugly and folks tend to  frowned upon them. 

Rgds

This must be the face to avoid then Joe . 

1 hour ago, Nucejoe said:

 You might call, old balance and new hairspring matching  a miracle.

 

Or a very good watchmaker