Omega cal 625 balance staff - is it different to cal 620?

[mikepilk]

Q. Can anyone ( @JohnR725 ?) tell me whether the balance staffs for cal 625 is the same as 620 ? (I think I've discovered they aren't) 

I needed to fit a new balance staff to an Omega 625.  I did my usual research (Cousins, Bestfit, Jules Borel, Balancestaffs.com etc) and found almost no references to cal 625 staffs, apart from Cousins who say it is discontinued.  Jules Borel database says it's the same part as cal 620 (part 620/1321). Some of the adds on ebay also suggest the 620 and 625 use the same staff. I concluded they must be the same. So I fitted one.

 It seemed the correct length and the balance spun nicely.  Until I fitted the roller, which rubs on the lower jewel fitting. Something not right. 

Looking in the Incabloc datasheets, it has different entries for 620 (hole .075) and 625(hole 0.80). D'oh!

This would explain my other thread with the loose collet.  ("Solid collet loose on Omega 625 - best fix?"). 

I think I've fitted the wrong part. If so, the correct parts seem VERY rare.

 

[AndyGSi]

From what I've found the 620 isn't compatible with the 625.

 

So the 625 balance complete is shared by the following movements.

But strangely the 593 balance doesn't show as compatible with the 625?

Edited July 12, 2024 by AndyGSi

[mikepilk]

The 593 cannot be compatible. When I fitted the 520 balance the length was about right, whereas it's 0.57mm longer for the 593.

Jules Borel say it's the same as the 620, and also the Tissot 2141/2 as shown above

 

For "Balance complete" Cousins show two different balances and a staff just for the 625.

Maybe there's a non incabloc version where the staff is common?

 

 

 

 

 

Edited July 12, 2024 by mikepilk

[AndyGSi]

So firstly are you sure it's a 625 that hasn't been messed about with?

Secondly is there any reason why you just want a staff and not just get a complete balance?

[mikepilk]

Yes I'm sure it's a real 625. I thought a new staff would be a cheap and simple fix. I'll buy a cheap donor movement and swap the balance.

[nevenbekriev]

What happens if the pallet fork bridge is in place? Does the balance not touch it?

[mikepilk]

1 hour ago, nevenbekriev said:

What happens if the pallet fork bridge is in place? Does the balance not touch it?

Yes it does. So there must be a specific balance staff for the 625.  But a global search on ebay for Omega 625 1321 - finds nothing.  Very strange.

[Nucejoe]

6 hours ago, mikepilk said:

there must be a specific balance staff for the 625.  But a global search on ebay for Omega 625 1321 - finds nothing.  Very strange.

Hi mike, 

 In unmodified families of movements  , parts are often listed by designation of their base caliber . 

 So,  identify Omega 625's base caliber, and search for it, you might need to expand your search for caliber 625 which might  have undergone slight change in dimensions.

For example, Omega 630, 630, 635  might all member the same family, but any member might have undergone slight change in dimensions, yet all beat the same and parts nearly  interchange . 

 In short you will find the staff to fit perfect, finding it starts with identifying its base caliber.

Check this,

https://www.spareparts-watches.com/product/1210449/omega-630

Good luck

 

Edited July 13, 2024 by Nucejoe
corrections

[Nucejoe]

11 hours ago, mikepilk said:

Jules Borel say it's the same as the 620, and also the Tissot 2141/2 as shown above

 

For "Balance complete" Cousins show two different balances and a staff just for the 625.

Maybe there's a non incabloc version where the staff is common?

 

 

 

 

 

Spareparts.watches  show 620 as the base caliber also, so staff should fit 625 , as you say perhaps different shock systems and if non fits, balance wheel might not belong to this family, someone might have build a non related balance complete to fit, so you should make sure you have the right balance wheel.

 

 

8 hours ago, nevenbekriev said:

What happens if the pallet fork bridge is in place? Does the balance not touch it?

That just shows the roller table fits on the staff and holds the impulse jewel at the right distance from centre axis , doesn't guarantee all other section of staff are right and fit.

[mikepilk]

9 hours ago, Nucejoe said:

In unmodified families of movements  , parts are often listed by designation of their base caliber . 

 So,  identify Omega 625's base caliber, and search for it,

The first thing I always do @Nucejoe, is determine the base calibre - for which Ranfft was useful.

Ranfft suggests the 620 is the base calibre

But I have some spare 620 movements, and apart from the size, they are totally different, e.g. two bridges on the 620, a single bridge on 625. Looking at the parts list for 625, apart from the stems, ALL parts are different.

How can the 620 be the base movement when every part is different?

Which is why I was slightly surprised when it was suggested the balance staffs were the same

Emmywatch.com suggests for Omega 625 the base movement is Zenith 30.5. But on the new Ranfft database, the entry for Zenith 30.5 says that Omega 625 is the base calibre 

Neither Jules Borel or Cousins list a staff for Zenith 30.5.

All there references suggest the balance staffs are the same - except Incabloc, which show different hole sizes

 

Edited July 13, 2024 by mikepilk

[AndyGSi]

1 hour ago, mikepilk said:

Ranfft suggests the 620 is the base calibre

I couldn't find anywhere on Ranfft that suggests the 620 is the base calibre, it's part of the family but this isn't the same?.

All I could find was that the 620 shares parts with the 670s and it does show the balance staff the same U2920.

Also Incabloc parts are completely different across the 2 movements.

Edit

There is a Balance on Cousins for the Tissot 2141.

Just realised that's a roller not a staff.

 

Edited July 13, 2024 by AndyGSi

[mikepilk]

25 minutes ago, AndyGSi said:

All I could find was that the 620 shares parts with the 670s and it does show the balance staff the same U2920.

Also Incabloc parts are completely different across the 2 movements.

I've seen the U2920 referenced several times. What are these "U" numbers?

From your pics you can see that the holes are different - 75 and 80. 

I think the easy option will be a donor movement. Fortunately there's a few cheap ones about.

Edited July 13, 2024 by mikepilk

[caseback]

27 minutes ago, mikepilk said:

I've seen the U2920 referenced several times. What are these "U" numbers?

I could be mistaken, but I believe they're numbers from the German supplier "Flume".

[Nucejoe]

 I wonder if  the staff was made by another manufacturer for Omega and Zenith?  Conceivably Omega could have placed order for staffs specially made for it, by the same token  for Zenith . 

 I have parts for ETA movement that specify " specially made for west end watch Co" on the package, and it doesn't fit in a movement of same caliber made by others than West end watch.

Based on the above observation ,  I guess if a staff comes in package stamped   " Omega ...."    it will fit Omega. 

Cheap generic staffs  did not go by orders to specially make for a company.

 Rgds

 

  

Edited July 13, 2024 by Nucejoe
Grammer

[JohnR725]

7 hours ago, Nucejoe said:

 I wonder if  the staff was made by another manufacturer for Omega and Zenith?  Conceivably Omega could have placed order for staffs specially made for it, by the same token  for Zenith .

What's interesting with the Swiss watch industry is the perception that for instance Omega would make 100% of all other parts? For instance here's a link to the YouTube video the company's been around for how many years? Now as you can see everything it has a CNC and their making watch parts for who exactly what how everybody in Switzerland probably. So yes conceivably all kinds of parts found in the watch have been outsourced to other companies.

https://youtu.be/6Skc3QGISCA?si=Qf7D01fVDdUFx0Ku

On 7/12/2024 at 8:56 AM, mikepilk said:

Jules Borel database says it's the same part as cal 620 (part 620/1321).

So I did this a little bit different I looked up Omega 620 and wind up with two separate balance staffs? Then if I look at the reference for 625 balance staffs once again there's two of them but I suspect they're probably identical even though the listing below says there are different? But in real life there supposed to be one staff the reason for this is an off to go to the best fit online would be the 100 number would be the generic best fit and the 723 number would be for Omega original. But they both should be identical. The problem sometimes with aftermarket balance staffs are they may not actually be identical. This is why when replacing balance staffs you need to use a micrometer and measure the old versus new preferably before you start to assemble and then discover there's a discrepancy.

OME 620 100/2238 STAFF/OME 620 BESTFIT BALANCE STAFF

OME 620 723/926 1321/OME 630 GENUINE BALANCE STAFF

Okay I'm having a confusion? Currently I'm on the best fit site and I wonder verifies of staffs you really do cross reference here and they don't? Okay let me look up the 625 parts Okay this is weird for the 625 parts there are no balance staffs listed at all not a generic or an original?

Okay let's look up cross references the parts such as 100/2238 Now we have an interesting problem I'll just copy and paste

Not expect anything different but let's look up the other reference number

Tech sheets can be fun can't they? So the initial 620/625 tech sheets and looking as it does not reveal anything of use and I did not see a balance staff at all. But further searching in the computer revealed a new verse 625 tech sheets with an interesting paragraph

Man I found I have a much much newer 625 parts list one that of course every single corner is watermarked so not that I give it to you but it does confirm that for the most part all the parts are unique to the 625 and of course there is no balance staff but there is a roller with the interesting part number

So it does look like the roller table interchanges with the 620 but as we don't have a balance staff number and nothing else is now confirming?

I thought I'd look in the bestfit physical book itself but it only shows the 620 because the 625 is after the books were printed. I am guessing that somebody made an assumption that the 625 is more or less identical to the sixth 20 and didn't read the one technical sheet that I quoted up above where the most part it is not. It's one of the problems of the technical reference material where this stuff was readily available into the 70s and then when the watch companies got well hate us all the amount of technical information available to us dramatically shrinks.

 

 

 

 

On 7/12/2024 at 8:56 AM, mikepilk said:

I needed to fit a new balance staff to an Omega 625.

Out of curiosity why did you need to change the balance staff? Then you do have to be careful in that the 620 versus 625 for instance a running at different frequencies which means the balance completes are obviously not going to be the same and even some of the subcomponents conceivably I didn't look the roller tables may be different but the reference I'm looking at says both balance staffs should be the same.

 

 

 

 

 

 

723/926   STAFF, INCABLOC   1321/OME 620

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=[^]D`FY

100/2238  STAFF, INCABLOC

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=U\ZDYFVM

 

[Nucejoe]

11 hours ago, mikepilk said:

The first thing I always do @Nucejoe, is determine the base calibre 

How can the 620 be the base movement when every part is different.

I did a fantastic job confusing you mike. 

 Base caliber does not mean , the base one and its variants beat the same, which in turn means escapement and gear train have to be different so hands show time right. 

 Roller table assembly doesn't need  to be different in  escapements that don't beat the same.

Roller table and impulse jewel together with fork horn,  have to do with lift angle.

A one caliber might come in many bridge layouts.

Cal 620 is definitely the base cal and 625 a variant of it, and  traditionally staffs are the same and interchange.

Must admit you have a confusing one on bench. 

Rgds

 

 

 

 

 

[mikepilk]

1 hour ago, JohnR725 said:

Okay I'm having a confusion?

Me too !

Welcome back @JohnR725, I've been awaiting your response. I thought that with your access to Omega documents you would clear it all up 

I've never been so baffled before with a movement. The Incabloc document lists different hole sizes, so the staffs must be different (?) 

1 hour ago, JohnR725 said:

Okay let me look up the 625 parts Okay this is weird for the 625 parts there are no balance staffs listed at all not a generic or an original?

Yet Cousins do list a part

 

1 hour ago, JohnR725 said:

Out of curiosity why did you need to change the balance staff?

Because the bottom pivot was broken. How you do that with Incabloc, I don't know.

I've just about given up on understanding the balance staff situation, so I will just find a donor movement.

I do have a spare 625 movement, in very good condition complete with nice dial and hands. I've been waiting years to find a nice case for it. I don't want to strip it for parts, so will look for another cheap movement.

[AndyGSi]

15 minutes ago, Nucejoe said:

Cal 620 is definitely the base cal and 625 a variant of it, and  traditionally staffs are the same and interchange.

620 is not the base calibre for the 625 as shown by @JohnR725 as this is a completely independent movement.

A base calibre is one that is then modified to create a new calibre as an example shown below.

The base calibre here is the 2202A which is then modified with the parts shown to create the 2220A

 

 

[mikepilk]

1 minute ago, AndyGSi said:

620 is not the base calibre for the 625 as shown by @JohnR725 as this is a completely independent movement.

If you look at my post above where I show the parts list, the only parts common between 620 and 625 are the stems, and a couple of screws.

[AndyGSi]

2 minutes ago, mikepilk said:

If you look at my post above where I show the parts list, the only parts common between 620 and 625 are the stems, and a couple of screws.

My post was in response to Nucejoe

[Nucejoe]

@AndyGSi    Lucky Mr pilk posted this relevant page from good Dr ranfft's database.

Cal 620  &  Cal 630  beat 19800 per hour, so they share  exact same escapement. 

Cal 625   &   Cal 635      beat 21600 per hour, they both share same exact escapement . 

All are listed as  members of one family, and staff  U2920 fits all, regardless of the beat or complications.

 Cal 620 was developed before other cals listed there, so in the world of Omega and Zenith, cal 620 is called the base cal for this family.

No gear of 19800 and 21600 beaters, in gear trains interchange.

Roller tables and impulse jewels can be the same providing  lift angles be. 

So even if a group of members in a family beat different, same ole U2920 fits all.

Notice ,  Dr ranfft calls 620, 625, 630 and 635  a family, not

" completely independent movements " .

Rgds

[mikepilk]

I'm planning to buy a donor movement.  But ......

As I have spare 620 and 625 movements, I thought I'd compare the staffs. The 625 is a running movement, the 620 has no hairspring but the balance us good. 

I measured them both as about 2.19mm length.

This is from a cal 620 (no hairspring). The staff I fitted to the 625 balance looks just like this.

 

 

This is from a running cal 625, there appears to be more staff below the roller.

[AndyGSi]

So is it just the roller that's different between the 620 & 625?

Edit

Found these rollers on eBay and although not very good photos it looks to me like the 625 has a recess so sits further onto the seat?

620

625

Edited July 14, 2024 by AndyGSi

[JohnR725]

18 hours ago, mikepilk said:

I've been awaiting your response.

The reason I was missing was that the message board has been playing games again with my emails? In other words if I don't get an email I may not come to the message board. But this morning I was rather surprised with 19 emails going all the way back to July 11? Like they had been waiting someplace and suddenly they've all shown up?

7 minutes ago, AndyGSi said:

So is it just the roller that's different between the 620 & 625?

It looks like the only thing as far as the parts list is going to show is the roller table and the stem. The weird aspect is the parts list for 620 lists a staff and for the 625 it does not? I wonder if with all the exciting new changes that?

One of the minor annoyances with watch companies are if you look at older technical documentation oftentimes you'll see all kinds interesting parts that have been dropped off later tech sheets because they do not expect you to for instance replace a balance staff hence the reason it's not listed here supposed to purchase a balance complete.

 

15 hours ago, Nucejoe said:

Dr ranfft calls 620, 625, 630 and 635  a family,

Wonder if the doctor ever made a mistake? Then the definition a family could be interesting like their all physically the same size and that's what makes them a family.

I'm attaching a whole bunch of PDFs of parts listings and one technical document the 625.

If you look at all the parts lists you actually find two separate base calibers. The base caliber only list itself and the caliber that's based upon the base will reference the base caliber for all the parts not covered in the parts list. So in other words the movement based on a base caliber will only show us the secondary parts.

So for instance the 630 is based on the 620

Then the 635 is based on the 625.

 

  

Omega 635_1_2101.pdf Omega 630_complet_2100.pdf Omega 625_complet_2097.pdf Omega 620_complet_2093.pdf Omega 625_complet_4087.pdf

[nevenbekriev]

Mike, OK, You have the staff riveted on the balance. The roller doesn't fit as there is not enough lenght of the downside part of the staff. If I was You , I would turn the hub on the lathe so it will get thinner and let the roller get a little up on the staff. Sometimes it is easier to solve problems this way than wondering for several days what is not correct.