Roller interchangeability?

[bsoderling]

Hi all,

Working on an ETA 1080 with need for a new balance staff (broken pivot). Got the replacement staff and started to remove the roller from the staff. 

And believe it or not, the roller flips away onto the floor and makes a hole-in-one into a tiny 5 mm hole in the floor boards that I for some reason made many years ago. Gone for ever..:-(

As I have other broken balance staffs with rollers lying around, it was a short stretch to start thinking that maybe these things are not as movement specific as many other parts are? If a roller is possible to get onto the staff properly, possibly opening the hole a tiny bit if it doesn't go on properly, maybe it works...?

As far as I can see, one critical thing would be the radius from the center of the staff to the jewel in the roller. Does this change between movements or is it standardized in any way?

Grateful for feedback.

 

 

[Nucejoe]

Hi there, Not only the radius but other factors as well. Even if the watch runs with a wrong roller, profoumd effects on peformance is inevitable.

Regards joe

[bsoderling]

For the sake of learning, can you expand a bit on "other factors"...?

I can for sure see that how deep the jewel will go into the pallet fork opening, at what angle it will start to push etc. can influence significantly. But besides that ?

 

 

 

[nickelsilver]

Most escapements in relatively modern "normal grade" watches (say back 50-60 years) were made by one company, Fabriques d'Assortiments Réunis (now Nivarox). They had perhaps 6 different main ones that were used over various sizes and beats of watches. There actually is a chance that a roller from another similar grade, size, and beat watch might work. As an example, I bought a dozen NOS 13 ligne Unitas movements some years ago with no balance wheels. I had a box of NOS A.Schild balance wheels with hairsprings. The balances actually fit though they were really a bit too large in diameter (and the hairspring was too large in diameter to fit the regulator), but more surprising was the roller was a perfect match to the escapement. Like totally perfect.

A good way to see if you might be close is to measure the distances between the plate jewels for escape wheel- fork- balance. Easier said than done, best if done on a profile projector or toolmaker's microscope, but you can get fairly close with accurate calipers and a loupe and patience. Measure several times and take the average. Each escapement had its pointage, it's sort of a fingerprint. It's really only useful information if you are trying to replace a part that is unavailable, and have the time to do the legwork. Otherwise just order a roller.

[clockboy]

Without the old jewel (or assembly) for measurement it is going to be extremely difficult to determine the correct size of the replacement. Cousins sell Seitz roller jewels that increase in diameter size increments of 0.02mm. If it is the complete roller assembly that has gone missing then a donor movement will be the way forward. 

[bsoderling]

Hi and thanks for all the feedback. 

I wasn't aware that the roller jewels came with that kind of resolution on sizes but I can see that the jewel size can have similar influence as its position relative the staff center of rotation. 

Interesting info about escapement manufacturing history. Insights like that makes my hobby so much more rewarding. 

Again I am amazed by the variability in parts this industry managed to implement and control from a manufacturing and logistics point of view. 

Regarding my actual problem, I am a bit inclined to just try one of the rollers I have that may "fit" and see how it goes. I can always get the right one later and may learn something in the process. 

 

 

 

 

 

[rogart63]

Have some 1080 parts if you need any.  Is  the roller the same as the roller jewel? is it inca or non shockspring 

 http://cgi.julesborel.com/cgi-bin/matcgi2?ref=[_ZD[F

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=ETA_1080

Edited November 5, 2018 by rogart63

[bsoderling]

Hi rogart63,

That's a very generous offer, thank you. 

My movement is the Inca version and I have sourced a new balance staff that I think is a Rn 887.

Not sure about your question regarding roller being the same as roller jewel? Please educate me on that...

 

[rogart63]

48 minutes ago, bsoderling said:

Hi rogart63,

That's a very generous offer, thank you. 

My movement is the Inca version and I have sourced a new balance staff that I think is a Rn 887.

Not sure about your question regarding roller being the same as roller jewel? Please educate me on that...

 

Check if i find one. At the moment i am cursing a AS340 that has a broken jewel. 

[vinn3]

5 hours ago, bsoderling said:

For the sake of learning, can you expand a bit on "other factors"...?

I can for sure see that how deep the jewel will go into the pallet fork opening, at what angle it will start to push etc. can influence significantly. But besides that ?

 

 

 

   if you read up,  on vintage watches,  the roller jewel is glued in with -------  hide glue? -  which is soluble with most cleaning fluids and once it is un glued it  will work its way out, or fall out.  when you remove the balance ,   always check it out.  there is a procedures to align it. good luck,  cheers.  vin

[nickelsilver]

Is the roller table or roller jewel missing? 

Roller jewels are held in with shellac, which holds up to normal watch cleaning solutions, and will withstand rinsing in alcohol if done quickly (alcohol will dissolve it in time).

[jdrichard]

The only reason you need the safety roller is to prevent over banking when the impulse jewel kicks the pallet fork too hard on the banking pins. Is this the safety roller you at looking for or the roller table with jewel.


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[nickelsilver]

The only reason you need the safety roller is to prevent over banking when the impulse jewel kicks the pallet fork too hard on the banking pins. Is this the safety roller you at looking for or the roller table with jewel.


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Eta never made a watch with seperate safety rollers to my knowledge, those were more common turn of the last century up to the 40s maybe at JLC and other makers doing their own escapements.

[bsoderling]

Hi and thanks for the continued contribution to this topic. 

I didn't know that the safety roller and roller table could come as separate (or at least separable) items. I have only seen these as one integral part on the movements where I have swapped out the balance staff. Good to know if I should stumble on something unexpected. 

I have only used benzine + ultrasonic to clean balances and other parts and have never had any issues with dissolved shellack.