Which balance staff for Omega 26.5T3 ?

[mikepilk]

I've got an Omega 26.5 T3 (non-Incabloc) with both pivots broken on the balance staff.

There appears to be several versions available - Incabloc, normal, short, long. 

I've found Ronda 1855, 2796, 3880

Can anyone help as to which I need, or do I have to push out the old one and try to measure it ?

[Nucejoe]

According to ballancestaffs it is Ronda 2796.

Regards

[mikepilk]

3 hours ago, Nucejoe said:

According to ballancestaffs it is Ronda 2796.

Regards

They also have it listed as the other numbers too. 

[clockboy]

You need to take measurements of the old staff and compare to the drawing s at Balancestaffs.com  see below:

 

 

https://www.balancestaffs.com/omega.php

 

[Nucejoe]

Are all dimension for the three you listed the same?  

Expectedly different size  rollers and H/S collets .....etc   . 

You will remove the staff anyway, the right choice/ requirments  can then be determined with certainty.

Regards joe

[mikepilk]

But with both pivots missing, and two of the staffs only 0.05 mm difference in length !

I might be able to do it on the width at the hairspring collet.

[Nucejoe]

4 minutes ago, mikepilk said:

But with both pivots missing, and two of the staffs only 0.05 mm difference in length !

I might be able to do it on the width at the hairspring collet.

Right,  reffering to the model clockboy just posted, you also measure G the roller diameter .Though the pivot ligne( diameter) is not available to measure, other sizes are enough for selecting exact correct one.

[mikepilk]

I was hoping that the staffs changed with year /serial number. Seems not 

[noirrac1j]

1 hour ago, mikepilk said:

But with both pivots missing, and two of the staffs only 0.05 mm difference in length !

I might be able to do it on the width at the hairspring collet.

Measure as best you can. I purchased a balance from Balancestaffs.com and it was the wrong size. Its not their fault though...these older movements are difficult to source parts for. I looked up on J Borel and BestFit MATSYS and they both say 100/594 balance staff, but I can't fine the dimensions. If the Ronda is easier for you to get, then go with the 2796.

 

[Nucejoe]

Assuming the staff in the wheel you got was the correct one, Correct dimemsioms being the main issue,  the difference in pivot diameter 11.75 and 12 are not expected to produce beat error or problems of the sort, or even if we assume all the .05 mm difference in length is in section B, no fault is expected form that either.

I think larger J  forced into the wheel would have a roll in the wheel deformation, I am not sure though, perhaps experiences of Clockboy or OH comes to help and answer this. 

Inserting  any linge 12 pivot into the jewels answers some questions, for instance you can see the pivot end coming out of the reverse side of the jewel or not and how far it sticks out.

 All staff sizes are available,  further response coming in will help.

Regards joe

[rogart63]

2796 is for incabloc is 327 long 

1855 non incabloc is 310 long

But there is also a version for 26.5 that is 1856 that is 332 long 

All in my Ronda book . The 3880 i can't find under Omega. 

Found this and hope it can help out as the dimension on the collet is different. Maybe you can figure out which one you need by measuring . 

https://www.ebay.com/itm/Omega-balance-staff-26-5-26-5T1-26-5T2-26-5T3-100-axe-de-balancier-Unruhwelle-/201826585959

Edited October 20, 2018 by rogart63

[mikepilk]

2 hours ago, rogart63 said:

2796 is for incabloc is 327 long 

1855 non incabloc is 310 long

But there is also a version for 26.5 that is 1856 that is 332 long 

All in my Ronda book . The 3880 i can't find under Omega. 

Found this and hope it can help out as the dimension on the collet is different. Maybe you can figure out which one you need by measuring . 

https://www.ebay.com/itm/Omega-balance-staff-26-5-26-5T1-26-5T2-26-5T3-100-axe-de-balancier-Unruhwelle-/201826585959

I found that on ebay too - that's why I mentioned the collet size.

[noirrac1j]

You'll have to measure where the collet attaches and make an estimate on the height.

J

[JohnR725]

Bestfit online is nice but sometimes the physical books are nicer. So 594 is listed as non-Incabloc. Then the problem with finding the size of the staff is you have to have an idea of how long it is. So I've attached images for the 594 staff size and the equivalent balancestaff.com staff and its size. Then one of the problems with aftermarket replacement staffs even if they're made for a specific watch is they tend to vary a little by size. Usually there physically bigger to allow you to reduce things to fit. It's why the length isn't that important the pivots can be longer and then you can just shorten those. So it's always important with balance staffs to measure what you are taking out and comparing to what you put in to avoid unpleasant surprises.

Then because of the confusion I'm also listing of the Bestfit Incabloc number and its size just so you can compare to whatever. 

OME 26.5T3    100/594    STAFF/OME 26.5    BESTFIT BALANCE STAFF

OME 26.5T3    100/857    STAFF/OME 100    BESTFIT BALANCE STAFF  Incabloc

100/857
A  327
B  160
C 90
D 50
E 43

[mikepilk]

I've just measured the staff.  I Haven't removed it yet, so had to use digital verniers instead of a micrometer.

.... and realised that the roller and collet diameters (G and K above) the same for all the staffs !

My measurements are collet 49, roller 41.

I found this on an ebay ad :

If 2796 and 3880 are only for Incabloc, then it's got to be 1855/6. And from the collet sizes, it looks like Ronda 1856 is the one ?

 

 

 

Edited October 21, 2018 by mikepilk

[noirrac1j]

21 hours ago, JohnR725 said:

Bestfit online is nice but sometimes the physical books are nicer. So 594 is listed as non-Incabloc. Then the problem with finding the size of the staff is you have to have an idea of how long it is. So I've attached images for the 594 staff size and the equivalent balancestaff.com staff and its size. Then one of the problems with aftermarket replacement staffs even if they're made for a specific watch is they tend to vary a little by size. Usually there physically bigger to allow you to reduce things to fit. It's why the length isn't that important the pivots can be longer and then you can just shorten those. So it's always important with balance staffs to measure what you are taking out and comparing to what you put in to avoid unpleasant surprises.

Then because of the confusion I'm also listing of the Bestfit Incabloc number and its size just so you can compare to whatever. 

OME 26.5T3    100/594    STAFF/OME 26.5    BESTFIT BALANCE STAFF

OME 26.5T3    100/857    STAFF/OME 100    BESTFIT BALANCE STAFF  Incabloc

100/857
A  327
B  160
C 90
D 50
E 43

Yes I like physical books myself, but it's hard to beat online reference tools for convenience. Great, You found the measurements for 100/594! One thing you mentioned is the fact that many aftermarket staffs tend to vary, but keep in mind not everyone has a lathe or Jacot tool to shorten a staff or reduce a pivot--not trivial!

J

[mikepilk]

On 10/22/2018 at 5:08 AM, noirrac1j said:

Yes I like physical books myself, but it's hard to beat online reference tools for convenience. Great, You found the measurements for 100/594! One thing you mentioned is the fact that many aftermarket staffs tend to vary, but keep in mind not everyone has a lathe or Jacot tool to shorten a staff or reduce a pivot--not trivial!

J

The 100/594 looks almost the same as Ronda 1856 - length 330 v 332, collet/roller diameters only 0.01 difference. 

I'll go for which ever I can find.

I don't have a lathe, but do have a Jacot tool, so can only do minor adjustments.