ETA 1080 Balance

[RickB]

Hi all,

For an ETA 1080 I'm restoring, I ordered a new balance.
It's an ETA 1080 balance by Renata.

The balance does fit the existing jewels, but barely.
There's no side-shake and as a result there's too much friction to run.

Researching ETA 1080 balances, I found there are more types of balance staffs for the ETA 1080.
Different ones for Incabloc, Kif, etc.
The shock system looks most like the Kif, as in a thick cap jewel, but that's about how far the similarity goes.

The different balance systems don't have any number on the pivot widths, only on the dimensions of the rest of the balance staff.

- Would buying an ETA branded balance help, would it have narrower pivots than the Renata one?
- Swap out the existing balance jewels?
- Get something like a Jacot Tool and a burnisher to remove some material from the pivots.

Any input is much appreciated.

Cheers,
Rick.

[JohnR725]

always helpful to give us a picture so we can see what you're looking at.

did you measure the pivots the diameter of the old balance? Another way to do this would be to look up all the various balance staffs and get the specifications for those and see if there's a difference in pivots size.

[mikepilk]

Which balance did you buy? The Renata numbers are :

A pic of the shock jewels would help.

[RickB]

4 hours ago, JohnR725 said:

always helpful to give us a picture so we can see what you're looking at.

did you measure the pivots the diameter of the old balance? Another way to do this would be to look up all the various balance staffs and get the specifications for those and see if there's a difference in pivots size.

Thank you for your reply, John,

The pivot size is around 0.079 mm

 

3 hours ago, mikepilk said:

Which balance did you buy? The Renata numbers are :

A pic of the shock jewels would help.

Thank you for your reply, Mike,

The balance is the 156.

 

The shock jewels:

[Nucejoe]

6 hours ago, RickB said:

There's no side-shake 

How about end-shake?     is there any?

 

 

[RickB]

13 hours ago, Nucejoe said:

How about end-shake?     is there any?

 

 

Thank you for your reply, Nucejoe,

The end-shake is something I haven't checked, as it was immediately clear there was too much friction.

[Nucejoe]

21 hours ago, RickB said:

Thank you for your reply, Nucejoe,

The end-shake is something I haven't checked, as it was immediately clear there was too much friction.

 Lack of end-shake is more likely to be the issue, loosen the bridge screw to create some end shake. 

Side-shake isn't easily noticable and is an unlikely cause, no matter which 1080 balance you bought, it will run. 

According to master Nickelsilver micrometer can damage balance pivots the way shown in previous pics. 

Good luck pal.

 

 

[RickB]

8 hours ago, Nucejoe said:

 Lack of end-shake is more likely to be the issue, loosen the bridge screw to create some end shake. 

Side-shake isn't easily noticable and is an unlikely cause, no matter which 1080 balance you bought, it will run. 

According to master Nickelsilver micrometer can damage balance pivots the way shown in previous pics. 

Good luck pal.

 

 

Thank you for your explanation, Nucejoe,

I noticed the pivot not really fitting when I installed the balance on the balance cock.
I could lift the balance cock by lifting the balance wheel, that's how tight the fit is.

The side-shake I've determined by placing the jewel on the pivot of the old and new balance staff under the microscope.
On the old balance staff pivot, there is some wiggle room.
On the new balance staff pivot, there absolutely isn't any.

I will check the end shake soon.


The jewel on the old balance, I can even see space between the pivot and the jewel.

 

The jewel on the new balance, it doesn't rotate freely.

 

11 minutes ago, RickB said:

According to master Nickelsilver micrometer can damage balance pivots the way shown in previous pics. 

That, I do realize , is why I only measured the old balance remaining pivot.
Not risking measuring the new balance pivots like that.

Edited July 8, 2023 by RickB

[Neverenoughwatches]

25 minutes ago, RickB said:

Thank you for your explanation, Nucejoe,

I noticed the pivot not really fitting when I installed the balance on the balance cock.
I could lift the balance cock by lifting the balance wheel, that's how tight the fit is.

The side-shake I've determined by placing the jewel on the pivot of the old and new balance staff under the microscope.
On the old balance staff pivot, there is some wiggle room.
On the new balance staff pivot, there absolutely isn't any.

I will check the end shake soon.


The jewel on the old balance, I can even see space between the pivot and the jewel.

 

The jewel on the new balance, it doesn't rotate freely.

 

That, I do realize , is why I only measured the old balance remaining pivot.
Not risking measuring the new balance pivots like that.

Pivot burnishing time

[Nucejoe]

Does pivot not fit in the jewel hole on mainplate either?  I now suspect the jewel on cock,  might be a wrong one.

All ETA 1080 balance pivots fit and run in your watch,  that is a 11.5"' fits 10.5"' and you wouldn't know the difference, mostly would not even affect the amplitide if you were to test it on timing machines.

3 hours ago, RickB said:

The jewel on the old balance, I can even see space between the pivot and the jewel.

Yes , can be seen  even in the picture, so I guess the jewel hole is too small a round. 

3 hours ago, RickB said:

I noticed the pivot not really fitting when I installed the balance on the balance cock.
I could lift the balance cock by lifting the balance wheel, that's how tight the fit is.

The side-shake I've determined by placing the jewel on the pivot of the old and new balance staff under the microscope.
On the old balance staff pivot, there is some wiggle room.
On the new balance staff pivot, there absolutely isn't any.

I will check the end shake soon.

 

This all points to small jewel diameter on cock side.

Rgds

 

[RickB]

On 7/8/2023 at 6:33 PM, Nucejoe said:

All ETA 1080 balance pivots fit and run in your watch,  that is a 11.5"' fits 10.5"' and you wouldn't know the difference, mostly would not even affect the amplitide if you were to test it on timing machines.

This is very good to know, that takes out a lot of the variables.
 

On 7/8/2023 at 6:33 PM, Nucejoe said:

I now suspect the jewel on cock,  might be a wrong one.

Nucejoe, that's wonderful and completely spot on!
Big cheers to you!

I've tested it, this is the result,

Balance jewel from the main plate:

 

Balance jewel from the balance cock:



The jewel from the main plate slides over the pivot.
The jewel from the balance cock, doesn't.

[RickB]

This movement still is giving me a hard time.
Obviously the ETA 1080, being an ébauche movement, can consist of incompatible parts between 1080 movements.

To try to get some progress I ordered a 1080 donor movement, to see if the balance jewels could be swapped out, which of course they couldn't 

Pictures to illustrate:

The ETA 1080 donor movement.

 

On the left, the balance jewel from the donor movement.
On the right, the balance jewel of the target movement.
Even visually, it's obvious the hole in the jewel on the left is larger.

 

Both balance jewels of the target movement.
The hole seems to be the same size in both jewels.
It's not just the balance cock jewel that's too tight for the balance pivots.

 

1: Almost everything is documented about balance staffs for the ETA 1080, except the pivot width. Does anyone have this information?
2: What kind of shock system is used in my target movement, anyone an idea?
3: Where can I find balance jewels with a slightly larger hole which do fit the target movement and the new 1080 balance wheel?

Never would have thought sourcing parts can be so much harder than actually using the parts 

Edited October 3, 2023 by RickB