Poor Amplitude

[TheoB]

Hello all, 

I am new to this forum and still quite inexperienced when it comes to diagnosing faults. I was hoping someone could point me in the right direction for tracking down the cause of low amplitude.

Some Background: I recently acquired a 12s ‘Delmark’ branded pocket watch was not running. It had a broken mainspring, and as I couldn’t find any model number or useful information on the watch I replaced the broken spring with the closest available silver alloy equivalent. After manually cleaning and reassembling the movement I found it to have very poor amplitude around 110 degrease. I disassembled the movement and inspected the balance, staffs, jewels and train gears and didn’t find any obvious problem. With just the balance installed and given a slight perturbation it smoothly oscillates for several seconds without any sign of excess friction.  I have also installed each of the train wheels individually and looked at the end play with my 10x loupe but wasn’t really able to distinguish excessive play (although I have no real experience here). There also doesn’t seem to be excessive lockup in the escapement, and the banking pins are nonadjustable. Also, the balance cock rests directly between the banking pins when the mainspring is let down.  

It seems like there must be a glaring problem I am missing. Does anyone have any thoughts?

Best regards

EF7DDFED-5E61-4C34-8949-8A0692E977A4.heic

[jdrichard]

Does the palate fork Snap back and forth with the balance out? Have you tried running the motion works without the palate fork in to see if the power releases properly. Have you checked the cap stones for damage. The the impulse jewel loose?


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[TheoB]

Hi, 

yes the palate fork does snap back and forth. I have also tried running the motion works with the palate fork out and it seems to be smooth.

With the barrel and all the train wheels attached I can use my blower to gently puff on the escape wheel and the train spins rapidly. However I have noticed (particularly in smaller watch movements) that when blowing on the escape wheel they spin, stop, and slightly recoil against the mainspring. I do not observe this recoil in this pocket watch, the wheels simply stop (though I don't know if that matters here). 

yes I removed the cap jewels when cleaning and they are intact. I also polished the impulse jewel with a peg wood and it's solid. 

 

[saswatch88]

1 hour ago, TheoB said:

Hi, 

yes the palate fork does snap back and forth. I have also tried running the motion works with the palate fork out and it seems to be smooth.

With the barrel and all the train wheels attached I can use my blower to gently puff on the escape wheel and the train spins rapidly. However I have noticed (particularly in smaller watch movements) that when blowing on the escape wheel they spin, stop, and slightly recoil against the mainspring. I do not observe this recoil in this pocket watch, the wheels simply stop (though I don't know if that matters here). 

yes I removed the cap jewels when cleaning and they are intact. I also polished the impulse jewel with a peg wood and it's solid. 

 

What oils are you using?

when you replaced the mainspring, did you measure the strength of the spring or just the width and length?

You need to check balance staff pivot under a microscope, the tip could have gone flat, they should be concave since this is a Swiss movement. If they are flat it will cause too much friction and will result in low amplitude and the watch will run very fast.

You should see recoil when you let the train run down but can be difficult on vintage movements because of wear and tear, not sure the age of the watch but i have the same problem with 100+ year old American movements. Cracked jewels and worn down pivots. I replace the jewels but even so pivots are usually worn so i have to go through a bunch of parts movements and pick the wheels with the best looking pivots. No NOS parts available. If this is a 7 jewel movement then your gunna have a real hard time since pivot holes get worn down to the point where they are no longer round.

[TheoB]

I am using moebius 8000/4

I ordered the closest modern replacement I could find. The new one is maybe 0.0005”-0.001” thinner and maybe a thou less in width than the old one.

My strongest loupe is 10x so I may have to use one of the microscopes at work to really inspect the pivots and jewels. 

I don’t really know how old the watch is but I think it’s relatively modern as it has the Seitz style jewels (although no shockproof settings), also it’s a 17 jewel.

[Nucejoe]

56 minutes ago, saswatch88 said:

What oils are you using?

when you replaced the mainspring, did you measure the strength of the spring or just the width and length?

You need to check balance staff pivot under a microscope, the tip could have gone flat, they should be concave since this is a Swiss movement. If they are flat it will cause too much friction and will result in low amplitude and the watch will run very fast.

You should see recoil when you let the train run down but can be difficult on vintage movements because of wear and tear, not sure the age of the watch but i have the same problem with 100+ year old American movements. Cracked jewels and worn down pivots. I replace the jewels but even so pivots are usually worn so i have to go through a bunch of parts movements and pick the wheels with the best looking pivots. No NOS parts available. If this is a 7 jewel movement then your gunna have a real hard time since pivot holes get worn down to the point where they are no longer round.

@saswatch88 What tools do you recommend to measure the MS's strength. TIA.

[saswatch88]

59 minutes ago, TheoB said:

I am using moebius 8000/4

I ordered the closest modern replacement I could find. The new one is maybe 0.0005”-0.001” thinner and maybe a thou less in width than the old one.

My strongest loupe is 10x so I may have to use one of the microscopes at work to really inspect the pivots and jewels. 

I don’t really know how old the watch is but I think it’s relatively modern as it has the Seitz style jewels (although no shockproof settings), also it’s a 17 jewel.

If there is no shock protection i would date it to be pre-1940s. Seitz has been around a very long time, so i would not use that as a guide to dating, plus jewels could have been swapped out at any time during its life,

Also i would look into getting better oils. Synthetic oils. 8000 is a natural oil and not the best to use on escapement since it just whisks away. You should also be versatile in your oils, different viscosities are required in different areas of the movement.

The mainspring you got should suffice, and I dont think that would cause a major drop in amp. But is the width smaller or larger? In some causes even a thousands of an inch can cause rubbing on the barrel lid.

In your situation if the issue lies in the staff your looking at doing a staff replacement which is not for the novice. And the tools required can be costly.

Edited January 27, 2020 by saswatch88

[saswatch88]

48 minutes ago, Nucejoe said:

@saswatch88 What tools do you recommend to measure the MS's strength. TIA.

Mainspring gauge. You stick the MS in the slot and pull it down till it stops then that is your measurement. It’s called a Dennison gauge. You can use calipers but this will give you the Swiss Dennison size.

[nickelsilver]

OP, what is the inside diameter of the barrel, the diameter of the arbor, and the inside height? From the two diameters we can figure out the theoretical correct spring.

[Nucejoe]

4 hours ago, nickelsilver said:

OP, what is the inside diameter of the barrel, the diameter of the arbor, and the inside height? From the two diameters we can figure out the theoretical correct spring.

Thanks for your response. A formula?  Be useful to know. Doesn't the thickness or springnes factor in? 

 

 

[nickelsilver]

1 hour ago, Nucejoe said:

Thanks for your response. A formula?  Be useful to know. Doesn't the thickness or springnes factor in? 

 

 

There are a lot of formulas, but the most useful one I know of is this one:

L= Length of spring

R= barrel inside radius

r= barrel arbor radius

e= thickness

 

L= π (R² - r²)/2e  

You can add 10-20% to that for high grade pieces. This is for barrels that develop approximately 6.5 turns of wind, which covers 99+% of timepieces.

 

That solves for length. If you are missing a spring totally, or have zero confidence that the spring in place is close to correct, you can get a very close value for thickness by dividing the inside barrel diameter by 87. So for the OP's watch, imagining it has a barrel inner diameter of 16mm,  you get 0.18mm for the thickness. Without knowing the arbor diameter, we can imagine it's 1/3 the barrel diameter, so 5.3, Plugging into the above equation that makes for a spring 497mm long, maybe 50mm more or so.

 

To see how close that might be I checked my Generale Ressorts book for an A.Schild movement using a 16mm inside barrel diameter and I see one right off the bat that's 0.185mm thick, 540 long. Another 0.20 thick 460 long. So we're definitely in the ballpark with the calcs.

 

When working from nothing this will get you very close, and many cases be very satisfactory. You can go up or down a little in thickness if you find you are limping along or rebanking.

Edited January 27, 2020 by nickelsilver

[jdrichard]

Love the math


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[TheoB]

7 hours ago, nickelsilver said:

OP, what is the inside diameter of the barrel, the diameter of the arbor, and the inside height? From the two diameters we can figure out the theoretical correct spring.

sorry I only have my English dial calipers handy but the measurements I have are

Inside barrel diameter: 0.66"

Arbor diamater: 0.210"

height of barrel: 0.058"

thickness of barrel cap: 0.020"

I ended up ordering a 1.80 x .17 x 500 x 15 from cousins

8 hours ago, saswatch88 said:

The mainspring you got should suffice, and I dont think that would cause a major drop in amp. But is the width smaller or larger? In some causes even a thousands of an inch can cause rubbing on the barrel lid.

 

I went with a new spring that measured slightly less than the width of the old spring.

[TheoB]

*edited duplicate response

[nickelsilver]

15 minutes ago, TheoB said:

sorry I only have my English dial calipers handy but the measurements I have are

Inside barrel diameter: 0.66"

Arbor diamater: 0.210"

height of barrel: 0.058"

thickness of barrel cap: 0.020"

I ended up ordering a 1.80 x .17 x 500 x 15 from cousins

I went with a new spring that measured slightly less than the width of the old spring.

Are you sure of the height? That's the total height?- or the "depth" measuring from the rim? (Should be able to get a pretty close reading using the depth rod); 0.058" comes to 1.47mm...

 

Otherwise going from the above calculations you will could go with something closer to 0.19 thick, similar length or perhaps a little longer. Can you get a pic of the dial side? If there are no maker's marks on the movement it will allow identifying the maker, then finding the actual correct factory spring.

 

A jump of 0.02mm in thickness will definitely boost your amplitude but probably not 150+ degrees.

[TheoB]

2 hours ago, nickelsilver said:

Are you sure of the height? That's the total height?- or the "depth" measuring from the rim? (Should be able to get a pretty close reading using the depth rod); 0.058" comes to 1.47mm...

thats using a depth gauge to measure inside where the mainspring would sit up to the rim, the total height on the outside would be larger. 

attached is a pre-service photo of the dial side.

[saswatch88]

Wait....this may be a stupid question maybe i missed something. OP dont you have the original spring??? If so there really is no reason to be going nuts measuring the barrel.

[TheoB]

16 minutes ago, saswatch88 said:

Wait....this may be a stupid question maybe i missed something. OP dont you have the original spring??? If so there really is no reason to be going nuts measuring the barrel.

Correct I took measurements from the existing broken spring

[nickelsilver]

If you kiddos saw some of the "springs" I've seen in barrels.... you'd get yer calculators out.

 

I'll look in the books when I'm in the shop tomorrow, I'm sure we'll find the maker. Can you measure the outside diameter of the movement? 12s is American but that's a Swiss movement.

 

 

[saswatch88]

27 minutes ago, nickelsilver said:

If you kiddos saw some of the "springs" I've seen in barrels.... you'd get yer calculators out.

I'll look in the books when I'm in the shop tomorrow, I'm sure we'll find the maker. Can you measure the outside diameter?

that is true you never know what someone else may have used before, unless you are familiar with manufacturer, caliber and grade there is no way to tell. Which is why i stopped working on swiss trench and pocket watches, way too many movements out there and no resources on them. Thats why I made the switch to American movements. plenty of resources and NOS parts available, and they hold much more value since the craftsmanship of the time was unmatched compared to the swiss.

[nickelsilver]

Thats why I made the switch to American movements. plenty of resources and NOS parts available, and they hold much more value since the craftsmanship of the time was unmatched compared to the swiss.

Not too sure about that but the Americans did make good movements with plenty of spares, problem is a lot of those movements got worked on by non-watchmakers over the years and they're

trashed

.

I'm American, worked on tons 20+ years ago, and it's such a treat to see an "abused" movement here now. Worst cases I've seen in the last 10 years were 2 Elgins recased as wristwatches by some micro brand, dials glued on, hairspring collets split and glued on, banking pins spread like they were working in Amsterdam, half a dozen other things. Nothing against Elgin- this microbrand was selling these as "restored" movements. As a Yank I brought them back to good and only charged regular price out of pride.

Used to see similar hacks in the States. Rarely (but do still) see such mic-mac on Swiss pieces here.

[saswatch88]

42 minutes ago, nickelsilver said:

I'm American, worked on tons 20+ years ago, and it's such a treat to see an "abused" movement here now. Worst cases I've seen in the last 10 years were 2 Elgins recased as wristwatches by some micro brand, dials glued on, hairspring collets split and glued on, banking pins spread like they were working in Amsterdam, half a dozen other things. Nothing against Elgin- this microbrand was selling these as "restored" movements. As a Yank I brought them back to good and only charged regular price out of pride.

Used to see similar hacks in the States. Rarely (but do still) see such mic-mac on Swiss pieces here.

Nothing makes me more sick then to see the hackers re-case these quality timepieces, these movements are works of art to me. There are a few guys i know that re-case these and they sell them for upwards of $3000, not gunna mention names here but i swear its sacrilege to the original makers and highway robbery to the buyers even though the craftsmanship is top notch they are still only re-casing movements that are worth anywhere from $20-$100 tops.

But i do agree I say these movements are like a box of chocolates, you never know what your gunna get. And they have been touched so many times in the last 100 years you never know had their dirty little unexperienced fingers in there. However i just feel like quality is unmatched compared to swiss. Take the Hairspring for example....i RARELY come across a mangled or damaged hairspring compared to the swiss. Even balance staffs hold up better, since americans used flat pivots and swiss was concaved, overtime the swiss pivots would flatten and i would then have to reshape them with diamantine powder then adjust the jewels for end shakes, never had to do that on a waltham or elgin.

[vinn3]

    please explain " re cased pocket watch".   during the era when those  were   popular.case and the mvt. could be sold separitely by the jeweler .   my granfathers elgin RR case could be sold with 2 diferent number of jewels.   a jeweler would replace your gold case with silver or nickel  -  if times were  tough.    vin

 

 

[nickelsilver]

    please explain " re cased pocket watch".   during the era when those  were   popular.case and the mvt. could be sold separitely by the jeweler .   my granfathers elgin RR case could be sold with 2 diferent number of jewels.   a jeweler would replace your gold case with silver or nickel  -  if times were  tough.    vin

 

 

How did they change the movement jewel count by going from precious metal to german silver?

 

[vinn3]

5 minutes ago, nickelsilver said:

How did they change the movement jewel count by going from precious metal to german silver?

 

   a solid gold case was replaced with a german silver case  and the   jeweler bought the case..   i have another old watch with gold hands and a silveroid case  - from  "the gold rush era"    i'll post a mvt. shipping case if you like.