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Pierce 134 Running Fast

margolisd

By margolisd
in Watch Repairs Help & Advice

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margolisd WRT Addict

margolisd

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Hi all. I’m working on a Pierce 134 movement. It’s running super fast. +900 seconds a day. Here’s what I’ve checked so far.

The amplitude is around 205.

I thought maybe I had the wrong main spring installed so I switched back to the original one that was already in it. No difference.

The end / side shake on the balance feels normal. The same issue occurs in all positions consistently.

The watch is nicely in beat and the balance well poised. The spring is flat, clean and not touching itself. The index curve looks sound.

The only possibility I can think of is that the hairspring is too short. But I wanted to see if anybody here had any ideas before replacing.

 

 

 

 

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clockboy Distinguished Member

clockboy

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Highly unlikely it is the mainspring. Normally running fast is caused by the hairspring effectively being too short. When I say effectively I mean the coils are touching or distorted. Magnetism can cause havoc with a mechanical watch so I would de-magnetise the movement first before any adjustments. After this if no improvement clean there HS and balance jewels in naphtha or a degreaser re-lubricate the cap jewels and check again. 

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margolisd WRT Addict

margolisd

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No resistance in the motion works or train. Although wouldn't that make it run slow?

It's a replacement hairspring found on eBay from an old watch sold for parts. So it could just be the wrong hairspring. It's the only one I've got so nothing to compare it to.

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clockboy Distinguished Member

clockboy

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Ok the HS is the most likely culprit it is either too strong our not long enough. If I remember correctly the test for a HS strength is as follows. Put the balance bridge on a tack the HS should then suspend the balance by no more than 1/2 inch. If it is less than this it is too strong if it hangs lower than 1/2 inch it is too weak. 

 

930819425_Screenshot2018-11-1720_58_19.png.8a8d7957a2bd95ba623daa9e769e6d88.png

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StuartBaker104 Distinguished Member

StuartBaker104

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22 hours ago, clockboy said:

Ok the HS is the most likely culprit it is either too strong our not long enough. If I remember correctly the test for a HS strength is as follows. Put the balance bridge on a tack the HS should then suspend the balance by no more than 1/2 inch. If it is less than this it is too strong if it hangs lower than 1/2 inch it is too weak. 

 

930819425_Screenshot2018-11-1720_58_19.png.8a8d7957a2bd95ba623daa9e769e6d88.png

That’s a great tip to remember for the future!

Margolisd - have you taken a good look to check that the second coil on the h/s isn’t touching the curb pin on the regulator? It’s all a bit cosy in there on these

I could take a couple of pictures of balances I have for these so you can compare the number of coils if that helps

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StuartBaker104 Distinguished Member

StuartBaker104

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Oh so easy to say I’ll take some pictures, but harder to achieve! iPhone through a microscope harder than it ought to be...

Known good balance...

5C8B8A11-B5B4-421C-874D-F9CEB9BBA2A9.thumb.jpeg.18f6cdb901a96f123d3815e8c931a7f8.jpeg

and a couple of others with less provenance, but removed from 134s. One has a broken staff so I know I’ve never run it.

C8BC1613-A73A-4CEF-BCF9-73DE432D883E.thumb.jpeg.205cc2980f59cb045c6871db29500bc0.jpegD7F8EDCD-2152-4EAD-8222-624E7A6C007C.thumb.jpeg.f65ea37b86b73e97679d9458160b2768.jpeg

 

I also spotted something else which might be worth a look. Most of these that I’ve taken apart have had part of the underside of the balance cock filed away near the stud hole. This could be because aftermarket or just later balances have a larger diameter hairspring - not pictured here as it’s fitted in a movement right now, but I did buy a NOS renata balance a while back that seemed too large to fit comfortably... hence my comment in the previous post about watching out for the 2nd coil touching the curb pin.

DC943B30-C6C5-457F-83D4-2E43B15D4F43.thumb.jpeg.0c1b2cac4df5ca5bf4bc2b0039e17988.jpeg

Finally I tried the dangling distance test... more like 0.33”  than 0.5”

D02297C5-D2BE-4B9A-85E2-770083A55273.thumb.jpeg.f5fa2702c39deeffe10f91fa64cf353a.jpeg

 

 

 

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JohnR725 Distinguished Member

JohnR725

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On 11/17/2018 at 11:32 AM, margolisd said:

It's a replacement hairspring found on eBay from an old watch sold for parts. So it could just be the wrong hairspring. It's the only one I've got so nothing to compare it to.

your replacement hairspring? The old watch is it the same grade the same model or something different that just had a hairspring physically that looks correct?

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margolisd WRT Addict

margolisd

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So... I think the problem is with the hairspring. Interestingly, in removing it to measure on the tac, I managed to damage it slightly. When I went in to repair it, the metal was like putty. The lightest touches were creating bends and the metal didn't feel as springy as I'm used to. Do hairsprings fatigue with age?

Thanks for your brilliant pics Stuart. The number of coils matches mine. So I can at least eliminate that. John, it could well have been replaced with the wrong spring by another repairer and the watch abandoned before I bought it. Hard to say.

I'm puzzled though because if the spring is weak, surely that would produce a high amplitude slow beat?

This is a slow motion video of the balance in action. Do you think the amplitude looks normal?

Anyway, I've bitten the bullet and ordered a new balance assembly. Let's hope that solves everything :)

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JohnR725 Distinguished Member

JohnR725

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4 hours ago, margolisd said:

John, it could well have been replaced with the wrong spring by another repairer and the watch abandoned before I bought it. Hard to say.

I'm puzzled though because if the spring is weak, surely that would produce a high amplitude slow beat?

Hairspring characteristics are interesting and unfortunately very complicated. Simplistically hairsprings have two characteristics. The strength is required to unlock the escapement. The mainspring supplies the energy to  rotate the balance wheel but the hairspring pulls the balance wheel back and unlocks the escapement. Then there is the frequency aspect usually the hairspring is vibrated to the specific balance wheel it's on. So swapping hairsprings is in general a bad idea and usually doesn't work.

A exception to the rule of the hairspring must be vibrated to the balance wheel is or was American pocket watches. these were the hairspring is with over coils which have to be in very exacting locations. So it's easier to make these hairsprings separate for the balance wheels to get their exacting characteristics. Then there placed on the balance wheel and you use to build the by timing screw assortments. Then the swapping hairsprings isn't entirely an issue but getting those replacement hairsprings and the timing screws that's definitely a challenge today.

then if you want to understand hairsprings, precision timing and stuff like that the book I listed below is a must have. Along with two videos that make hairspring vibrating look insanely easy when it really is not. The second video showing the final product of how closely the vibrated spring matches the master balance wheel did not occur instantaneously it would take a lot of time to get there.

Watch Adjustment by Hans Jendritzki
ISBN-10:     2883800294     
ISBN-13:     9782883800298
Format     Hardcover
Author     Hans Jendritzki
Publisher     Antoine Simonin, 2006
Pages     107

https://www.youtube.com/watch?v=-hLorcrSRNs

https://www.youtube.com/watch?v=M5LEN66vxgc

 

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margolisd WRT Addict

margolisd

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Wow great videos. They make it look easy. He’s like a heart surgeon. And thanks for the detailed reply. I’ve read Practical Watch Adjusting by Donald De Carle and found it very useful. But I’ll take a look at this too.

One question. Where might I find “blank” hairsprings if I wanted to experiment doing my own springing?

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JohnR725 Distinguished Member

JohnR725

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the short answer is there are no more blank hairsprings? Somewhere I have a BHI article this was several years back where they discovered that the blank hairsprings that were once available for purchase are gone. The Swiss like to re-consolidate from time to time basically to improve manufacturing and reducing cost. this affects hairspring manufacturing because now rather than making a whole bunch of separate Springs of various sizes and dimensions for the manufacturers they now manufacture exact hairsprings for the exact watch. This means the watch manufacturer either vibrates the Springs themselves or they just send the balance wheels to the hairspring company. The unfortunate consequence is we no longer have generic hairsprings to vibrate.

 

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margolisd WRT Addict

margolisd

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So my new balance assembly arrived from Australia this morning. I was a bit dubious about putting in the terminal curve as I've not done many before. But I think I got it pretty good after a good hour of trial and error. And the watch is finally running at the correct speed! So I guess the spring was wrong all along. So satisfying to get it finally working properly! Hooray!

IMG_1186.jpeg

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