Analyzing with (nearly) constant torque

[Delgetti]

Over the last weeks I followed VWatchies thread about his ETA 2763 showing erratic amplitude:

https://www.watchrepairtalk.com/topic/28929-serviced-eta-2763-having-erratic-rate-and-amplitude/page/4/#comment-245378

I have a similar problem on an Omega 861. The base movement shows alternating amplitude in both horizontal and vertical positions. The range is more than 25 degrees, no periodical behavior, pure random.

In the above quoted thread there was a lot of talk about the regulator pins, hairspring, collet, geartrain, etc. and I do not doubt that all these may be sources for the problem. However, I couldn‘t get one question out of my head: Can the problem be on the other side - mainspring, barrel, ratchet wheel? Some kind of error which prevents the barrel from delivering constant torque to the center wheel? To find out where to look I built the following setup:

I assembled the movement without barrel and ratchet wheel.

Then after some research and calculation about torque in the geartrain I 3D-printed this part and completed it with an axle and a pin.

 

The movement in a well chosen vertical position. Please notice the spoke of the center wheel.

Now the „torque generator“ is fitted to the center wheel. The axle is pushed into the pinion and the pin is lying on the spoke.

 

Finally I have to choose the correct weight to get a torque which results in an amplitude in the area of 280 degrees ( yes, watchmaking is an expensive hobby - my 2 cents).

And that‘s all. When the lever is in nearly horizontal position this setup provides a nearly constant torque on the center wheel for several minutes (I assume you live in an area with constant gravity).

 

For me this one answered my question. The alternating amplitude was gone, less than 4 degrees fluctuation now, which is always the case with my Weishi. So the source of my problem is somewhere in the area of the barrel - will work on that the following days.

[Endeavor]

Yes, same as with my 861.

The 861 has a problem with wear of the arbor in the barrel bridge and the spring barrel self around the arbor can be worn; a common problem with the 861.

In my case, the wear of the arbor hole in the barrel bridge wasn't too bad, but combined with the main-spring barrel, I had all sorts of problems. Luck had it, that there were a few cheap (€120!) 861 NOS barrels+arbors on eBay and I snapped one up....... that helped a lot.

I still have a wave-line and amplitude fluctuations, but on the wrist the watch has gained no more than 2.8 seconds in 2x weeks. I checked every day for consistency and it runs rock-solid.

I will try to find the thread in which we discussed this 861 wear-problem.

This is a part:

 

You could ask the seller if he has some more: https://www.ebay.de/itm/204594117199

Edited March 27 by Endeavor

[VWatchie]

1 hour ago, Delgetti said:

In the above quoted thread there was a lot of talk about the regulator pins, hairspring, collet, geartrain, etc. and I do not doubt that all these may be sources for the problem. However, I couldn‘t get one question out of my head: Can the problem be on the other side - mainspring, barrel, ratchet wheel?

I would say for sure! The source of a problem can be super complex to find and can of course also be a combination of errors that together cause the symptoms. Fault finding by function group or elimination as you do here is most of the time the only way to pinpoint the cause of the problem. Generally, it is my impression that we tend to underestimate the importance of investigating and if necessary remedying problems with the mainspring, barrel, arbor, and/or the barrel bridge and mainplate arbor bearings.

I must say I was impressed to see your 3D-printed part for eliminating problems beyond the mainspring-related parts!

BTW, the ratchet wheel has no role in the performance of the movement. Its only role is to wind the mainspring

Edited March 27 by VWatchie

[Endeavor]

BTW, this type of wear in the barrel bridge you have to look for;

[Delgetti]

13 minutes ago, VWatchie said:

BTW, the ratchet wheel has no role in the performance of the movement. Its only role is to wind the mainspring

I have to admit that I don't agree here. On the 861 the ratchet wheel is placed right on top of the barrel and underneath the bridge. In combination with some wear and dirt it could cause some scrubbing to the barrel and so influence the performance. 

[praezis]

Great experiment!

Maybe you would see periodic change if you could register rate and amplitude for longer periods. Passage of one barrel tooth takes about 5 minutes!

Frank

[Delgetti]

Agree, this setup cannot spot long term effects. But in my case the alternation was quite fast, about 7 peaks in 5 minutes. 

Btw: Endeavor was right. Bearings in the bridges were ok but barrel and cover itself have excessive sideshake to their arbor. Ordered a nos one. 

[Endeavor]

1 hour ago, Delgetti said:

Bearings in the bridges were ok but barrel and cover itself have excessive sideshake to their arbor

I tried to correct the play, but that went hopelessly wrong. The thickness of the barrel material, surrounding the center-hole, is too thin. All I achieved, with my staking-set, was opening the hole even further

Perhaps flat punches may work? Nothing to loose ......

 

 

Edited March 27 by Endeavor

[JohnR725]

15 hours ago, VWatchie said:

BTW, the ratchet wheel has no role in the performance of the movement. Its only role is to wind the mainspring

15 hours ago, Delgetti said:

I have to admit that I don't agree here. On the 861 the ratchet wheel is placed right on top of the barrel and underneath the bridge. In combination with some wear and dirt it could cause some scrubbing to the barrel and so influence the performance.

parts touching that aren't supposed to touch definitely would cause an issue. there not supposed to be touching there supposed to be independent which means that @VWatchie is correct that the ratchet wheel has no effect on performance. so if the ratchet wheel in your particular case is touching that is definitely going to be an issue and needs to be addressed.

14 hours ago, Delgetti said:

Btw: Endeavor was right. Bearings in the bridges were ok but barrel and cover itself have excessive sideshake to their arbor. Ordered a nos one.

did you know that the Swatch group service centers do not change mainsprings? Swatch group service centers have an infinite supply of spare parts so they just change the mainspring barrel the whole thing. Plus anything else the watchmaker doesn't like just gets replaced like anything related to the escapement they just replace the components because they can.

[nevenbekriev]

Nice experiment. As it will be no problem, please put a twice less mass (half of the two penies) and read the amplitude, will be interesting. I mean to determine what is the relation torque/amplitude.

[Delgetti]

37 minutes ago, JohnR725 said:

did you know that the Swatch group service centers do not change mainsprings? Swatch group service centers have an infinite supply of spare parts so they just change the mainspring barrel the whole thing. Plus anything else the watchmaker doesn't like just gets replaced like anything related to the escapement they just replace the components because they can.

I wish they would have done so in this case. The whole story went like this:

I sent my speedmaster to an omega service center about 10 years ago (at that point of time I haven't even started watchmaking). After the watch came back to me it had only about 6 months wristtime until january 2024 (not fair for this nice watch but the other pieces of my collection want wristtime too ). So my conclusion is that the barrel was already faulty when it came back from service, can't imagine that amount of wear in 6 months wristtime.

In january 2024 the performance on the wrist was quite bad, so I decided to have a look by myself. I have to admit that I didn't check the barrel close enough as I thought it must be ok, couldn't have issues after official omega service.

That was a mistake, I will learn from that. Follow the golden rule: Nothing is certain except death and taxes.

[JohnR725]

33 minutes ago, Delgetti said:

After the watch came back to me it had only about 6 months wristtime until january 2024 (not fair for this nice watch but the other pieces of my collection want wristtime too ). So my conclusion is that the barrel was already faulty when it came back from service, can't imagine that amount of wear in 6 months wristtime.

In january 2024 the performance on the wrist was quite bad, so I decided to have a look by myself. I have to admit that I didn't check the barrel close enough as I thought it must be ok, couldn't have issues after official omega service.

yes that's definitely not right at all.

I have a picture one of my friends has a Omega coaxial there was having issues to lose asking me where he should send it. As that's a specialty watch I suggested the service center. When he got it back he sent me a picture so the replace the dial as you can see the hands the mainspring barrel and I think the price was really quite decent considering all the stuff they can replace. So I do know they do change the barrels but

the other person I worked at the service center when I would ask questions and unfortunately I can't remember all the answers. I think a lot of the changing a parts is at the discretion of the watchmaker. Plus I don't know enough about the chronographs and whether that would be considered a vintage watch? I take some of the vintage watches may have been sent directly to Switzerland or another service center. Obviously with a watch like the one down below they probably have a infinite supply of parts is its relatively modern vintage stuff becomes more interesting even the watch companies don't have necessarily infinite supply of parts.

But no matter what the watch shouldn't disintegrated six months that's definitely an issue.

 

 

 

 

[Endeavor]

49 minutes ago, Delgetti said:

That was a mistake, I will learn from that

Sounds like the story with my Rolex. Poor (expensive) job done by an official Rolex dealer with an "in-house" watchmaker, hence I learned watchrepair and did the servicing myself. Same story as I learned with the Omega 861, again poor job by an "in-house" watchmaker by an official Omega dealer.

Once your watch goes through that back-door, you have no idea what is going to happening to it

 

6 minutes ago, JohnR725 said:

When he got it back he sent me a picture so the replace the dial as you can see the hands the mainspring barrel

Quite nice that they sent back the parts which had been replaced !

Edited March 28 by Endeavor

[JohnR725]

9 minutes ago, Endeavor said:

Quite nice that they sent back the parts which had been replaced !

you think you're going to sleep tonight you're not, you're going to ponder the question of what makes you think those of the right parts?

 

[Endeavor]

2 minutes ago, JohnR725 said:

you think you're going to sleep tonight you're not, you're going to ponder the question of what makes you think those of the right parts?

That would be something! Which brings me back to;

14 minutes ago, Endeavor said:

Once your watch goes through that back-door, you have no idea what is going to happening to it

 

[Neverenoughwatches]

1 hour ago, JohnR725 said:

you think you're going to sleep tonight you're not, you're going to ponder the question of what makes you think those of the right parts?

 

Haha. You're just in a wicked mood today John

[oldhippy]

I haven't gone through all the reading of what it might be or not. The first thing I would do if nothing obvious stands out is replace the mainspring, you have to start at the source of the power. Nine times out of ten that is the problem.  

[VWatchie]

20 hours ago, Delgetti said:

I have to admit that I don't agree here. On the 861 the ratchet wheel is placed right on top of the barrel and underneath the bridge.

I was not aware of that as I'm not familiar with the 861 calibre but I was speaking in general terms. Thanks for pointing it out!

4 hours ago, JohnR725 said:

there not supposed to be touching there supposed to be independent which means that @VWatchie is correct that the ratchet wheel has no effect on performance. so if the ratchet wheel in your particular case is touching that is definitely going to be an issue and needs to be addressed.

I thought it was somehow resting/rubbing on a very small section on top of the barrel. So, not really an exception to the rule then. Good to know!

Edited March 28 by VWatchie