Mainspring slipping, replaced barrel, spring, arbor, still slips

[Dmitry]

I am utterly stumped.

Tinkering with ETA 2790-1 I noticed that the mainspring started slipping after about 4-5 winds. 

I applied some barrel grease (8217) - no improvement.

I then notched up with a screwdriver the inner side of the barrel, no improvement, but probably killed the barrel by doing so.

I got a new mainspring, still no improvement.

I gave up and bought a new barrel and arbor, but since I could not locate one for 2790-1, i got one for 2750, which should still fit. It does, but still slips.

Attaching a few pictures here and looking for suggestions.

The inner diameter of the barrel is 11.2, the length of the sprint if about 40mm.

[Curare]

I think your problem is related to the inner coils of the mainspring were it hooks onto the arbour. It looks damaged, did you have to manipulate it to fit the arbour because the new mainspring arbour hole was too big?

I think what may be happening that as you start to put a wind in the way the mainspring inner coil is deformed it is releasing pressure on the bridle and causing premature slipping.

Was it an genuine mainspring or after market ? 

 

[nickelsilver]

There's like 13 recent discussions on braking grease, including one proposing braking grease is like a cult belief. There are different ones for different cases, I actually remember the Moebius numbers:

Glissalube A 8213 brass barrel

Glissalube B 8212 aluminum barrels

Glissalube 20 8217 general purpose

Kluber P125 high end high performance high price

 

Kluber has done the trick for me since I got some. Prior, used Glisslaube A or B as needed. One or two cases with smooth (unnotched) barrels required roughing up the barrel wall, long-term effect to be seen.

 

When I started working on my own cars at 17yo, I quickly saw I had to sink some money in tools. In watchmaking it's very similar, and you can get by with some very basic lubes, but at some point you have to get the good stuff if you want a good result.

[nevenbekriev]

Hi Dmitry,

First of all, not clear what it means "After 4-5 winds".

If it means "movements of the fingers when turning the crown", then this should be probably about one turn of the barrel arbor, then the spring is definitely not slipping, but the internal end is not attached well to the arbor.

If it means "revolutions of the ratchet wheel", then the revolutions should be about 6, the spring is slipping and another type of grease should be tried. But as 4-5 is not so far from 6, the watch will work and the power reserve will be at least 2/3 from the normal. Is it the case?

For sure the internal end is damaged and it is not clear how long this spring will be able to work before breaking.

[caseback]

To me this looks like a generic mainspring of which the inner coil was too wide and was pinched to make it smaller. Probably the slippage is between the inner coil and the arbor. You might try to heat it up a bit to make it softer and get it to fit better.

[Nucejoe]

Your 2nd circle of mainspring pushes on peak of the 1st circle as I marked in the pic, unhooking the eye from the catch.

The spring should wrap around the arbour, check this link.

https://omegaforums.net/attachments/mainspring_in_barrel_old-jpg.730785/

Edited July 31, 2024 by Nucejoe
correction

[Neverenoughwatches]

Its not fully determined which end is not functioning correctly but the inner coil close to the arbor certainly needs re-shaping to fit the arbor snuggly. You MAY need to warm up those inner bent coils to help the manipualtion stay if you do , use a low flame from a lighter, keep it short and direct it to as little area as possible, you dont want to soften any more of the spring than necessary. Round nose pliers to shape or around a piece of pegwood. When inserting the arbor set the hook back from the eye and carefully turn into it, you might need to press the inner coils back again to fit if you softened them.  While you're at it check that the hooking eye locks in tight with the arbor hook and there is no bevel on the touching surfaces where the hook can slip out under tension. This end should now be covered. From your explanation it sounds like you think the bridle is slipping too early on the barrel wall so might just be a change a grease required. 

[VWatchie]

It took me the longest to understand that braking grease doesn't have a braking effect but helps the spring slip just enough. Then I heard someone say that too much braking grease, I believe it was Kluber, would actually put a brake on the slippage. I don't know what to think about that.

[Neverenoughwatches]

19 minutes ago, VWatchie said:

It took me the longest to understand that braking grease doesn't have a braking effect but helps the spring slip just enough. Then I heard someone say that too much braking grease, I believe it was Kluber, would actually put a brake on the slippage. I don't know what to think about that.

I think it depends how you wish to term it H, braking and slipping seem like they are the two opposite ends of the scale and they are when they are at their extremes also but a fine line between them when nearing the point of slip.  The correct moment of slip is what counts. Maybe " friction grease " would be a better name,  so greases have different gripping properties. I suppose also to consider would be how much the spring will slip until is grips the barrel wall again so minimal amplitude is lost. Maybe there is a specification for this within the grease ? there should be considering how much some braking greases cost.   " slip distance " ?  " braking reaction " ?

[RichardHarris123]

The co-efficient of steel on brass us 0.51 dry, 0.19 with grease (dimensionless). Thus grease must decrease the friction.  I can only assume that braking grease does reduce friction but is formulated to do so at a predetermined torque.

[rehajm]

Braking grease like P125 is gritty to the touch. I’ve always assumed it was increasing friction or at least maintaining friction once the spring begins to slip, so the spring slips and catches smoothly and also reducing wear.

The problem is calling it ‘grease’ 

[Kalanag]

1 hour ago, VWatchie said:

It took me the longest to understand that braking grease doesn't have a braking effect but helps the spring slip just enough. Then I heard someone say that too much braking grease, I believe it was Kluber, would actually put a brake on the slippage. I don't know what to think about that.

Do some testing with different lubricants (as I did) and you get even more confused 

[Nucejoe]

Round end long nose pliers.

 

https://www.google.com/imgres?imgurl=https%3A%2F%2Fwatchmaking.weebly.com%2Fuploads%2F1%2F1%2F7%2F9%2F1179986%2F1001133_orig.jpg&tbnid=-4IOdneL5NtnpM&vet=1&imgrefurl=https%3A%2F%2Fwatchmaking.weebly.com%2Fmainspring.html&docid=DGmtsMvV-3yQcM&w=700&h=757&hl=en-US&source=sh%2Fx%2Fim%2Fm6%2F4&kgs=31f23541559d1c89&shem=abme%2Ctrie

[Dmitry]

An update - I have followed suggestions to make sure the loop around the arbor is centered and snug, but this has had no impact, it is still slipping. I now wonder if I need yet another mainspring, is there anything wrong with the mainspring that jumps at you that would cause the slippage?

[AndyGSi]

Are you sure the problem isn't with the arbor?

Edit

2nd thought is are you winding the spring in the correct direction?

Edited August 1, 2024 by AndyGSi

[Neverenoughwatches]

36 minutes ago, Dmitry said:

An update - I have followed suggestions to make sure the loop around the arbor is centered and snug, but this has had no impact, it is still slipping. I now wonder if I need yet another mainspring, is there anything wrong with the mainspring that jumps at you that would cause the slippage?

 

41 minutes ago, Dmitry said:

An update - I have followed suggestions to make sure the loop around the arbor is centered and snug, but this has had no impact, it is still slipping. I now wonder if I need yet another mainspring, is there anything wrong with the mainspring that jumps at you that would cause the slippage?

Maybe the bridle is not up the same stiffness as the original but probably just a case of using the correct grease to make it work satisfactory. 

[mbwatch]

21 minutes ago, AndyGSi said:

are you winding the spring in the correct direction

This is interesting. It isn't easy to tell from the one photo of the mainspring installed in the barrel, but a good close-up photo of the arbor alone would help

[Dmitry]

I am sure I am winding in the right direction. Have done this mistake in the past coupel times, the sound and behavior feels completely different than slipping.

I bought the watch as a non-runner, so in retrospepct I have no idea how authentic the spring really was. I bought a generic automatic spring from cousins based on specs and dimensions of the barrel.

Does anyone have any tech info on 2790-1 to validate mainspring specs? 

One other thing I wanted to check is usage of a bridle mainspring hooks into on some automatic watches. May it be that my 2790-1 was supposed to have one such bridle, on top of which the mainspring attached, but the frankestein I seem to have acquired had it removed?

[AndyGSi]

Looking back at your original post you say you got a barrel and arbor for a 2750 and a new mainspring?

Now although the arbour is the same on the 2750 & 2790-1 the barrel and mainspring aren't.

 

[Dmitry]

1 hour ago, AndyGSi said:

Looking back at your original post you say you got a barrel and arbor for a 2750 and a new mainspring?

Now although the arbour is the same on the 2750 & 2790-1 the barrel and mainspring aren't.

 

I got that exact mainspring you show for 2790. I tried it with the old original barrel and it was slipping too. What about that short bridal, are 2790s equipped with it?

[AndyGSi]

I would have expected the GR4014X to come complete with bridal as it's an automatic spring.

Are you sure you got the correct GR4014X and also the correct arbor?

 

[Dmitry]

I checked the barrels and indeed, they are different on the inside, despite having the same diameter. Th eone from 2750 has one larger cavity for the mainspring end to rest in, while 2790-1 has many smaller notches at about 30 degrees arc around the perimeter to catch the automatic slipping mainspring when over-winding. Here is the picture, there are a bunch of scratches on the side, probably to fix the slipping issue I am now dealing with. 

The mainspring I got has a longer fused automatic bridle at the end as typical automatic mainsprings would, but given that I have already changed the arbor, I wonder if I need to buy the GR4014-X explicitly, and if the old barrel with these scratches will still work, or if I now have to hunt down the specific barrel for 2790-1, there aren't many of those around.

[AndyGSi]

27 minutes ago, Dmitry said:

or if I now have to hunt down the specific barrel for 2790-1, there aren't many of those around.

 

There are a few complete as the eBay listings below but not sure what delivery would be to Canada especially from the european ones.

https://www.ebay.com/itm/364745874240?ff3=2&toolid=10044&customid=&lgeo=1&vectorid=229508&item=364745874240&ufes_redirect=true

https://www.ebay.com/itm/313044979567?ff3=2&toolid=10044&customid=&lgeo=1&vectorid=229508&item=313044979567&ufes_redirect=true

[VWatchie]

The only times I've had problems with the mainspring slipping way too early have been with Seiko and Orient springs when I've tried to replace them with Swiss Generale Ressorts generic springs. Very long story short my conclusion was that the alloys aren't compatible. For this reason, I always keep the original spring when doing a Seiko or Orient unless it is completely shot. Sourcing new springs for Seiko and Orient watches seems nearly impossible.

[Neverenoughwatches]

8 hours ago, VWatchie said:

The only times I've had problems with the mainspring slipping way too early have been with Seiko and Orient springs when I've tried to replace them with Swiss Generale Ressorts generic springs. Very long story short my conclusion was that the alloys aren't compatible. For this reason, I always keep the original spring when doing a Seiko or Orient unless it is completely shot. Sourcing new springs for Seiko and Orient watches seems nearly impossible.

Did you ever compare the bridles H , length thickness and stiffness ?