SET MAINSPRING - Myth or Really Truely POSSIBLE ?

[Brad Maisto]

So I was given a 16S South Bend grade 317 to get back into "working" condition from an old friend who found it in a drawer with some of his other small vintage trinkets. The watch appears pretty clean, but upon receipt the mainspring was fully wound and the the balance wheel was "overbanked", if I'm using this term correctly? So now I have to wonder how long this pocketwatch has been fully wound, and knowing this person who has been collecting for many years, it could have been sitting like this for many years.
I tried doing a search in this repair forum for "set mainsprings" without really finding too much prior discussion. I have seen where many repair people will automatically replace the mainspring when doing a routine cleaning?
So I guess I'm asking if there is any type of instrument or tool to test the "strength" of the current mainspring, to see if it really has lost any of its "power" so to speak?
And when a mainspring is considered "Set", what does this really mean?
Thanks in Advance for your comments, opinions, and/or knowledge.
Brad Maisto, Indiana Chapter 18 President
P.S. This is the same friend who sold me a South Bend "294" in a solid 14K yellow gold hunter case that needed a dial. Good thing dials are interchangeable from watch to watch !

 

[Skutt50]

I usually replace the mainspring just in case.

Otherwise to check if a mainspring is set you normally just look at it and how far it expands when let loose...... Now modern mainsprings are normally shaped differently than old and look like an S so you can not just compare a new and a NOS.

 

[klevay]

Set mainspring is not a myth. A watch itself will be a test instrument for it. You won't get a good balance amplitude with a set mainspring. One can also determine if the mainspring has to be replaced by the the way it looks. Usually, if relaxed mainspring in the barrel has more than two coils around the arbor, it is set. Also, if you look at the out-of-the-barrel mainspring and its coil diameter is less then 2.5 barrel diameters, it most probably has to be replaced.

 

[sderek]

The main problem with a set mainspring is loss of power reserve.
I was taught the 2.5 barrel diameter minimum, also, but I usually just check the mainspring in the watch. If it won't run for 24+ hours (with good amplitude), it's time for a new mainspring. But, you'd be surprised how many watches will run well, even with an old mainspring.

 

[psfred]

Actually, a brand new carbon steel mainspring should look exactly like a modern white alloy spring, but long ago has lost the reverse curve and become a coil shape.

Set springs have less power, so can cause fast running and reduced reserve -- a friend of mine had a watchmaker "save him some money" a couple decades ago by not replacing the mainspring in his 7 jewel Elgin. Had to wind it twice a day, although it kept time almost as well as his railroad grade watches. I dropped in a new white alloy spring and it works perfectly.

"Set" means the spring has become bent, having lost it's elasticity. When you remove a badly set one, you will understand.

My feeling is that one should always replace a blue steel spring with a modern white alloy one unless there is some important reason not to -- the customer demands an "original" spring even though the spring in the watch is very unlikely to be the one that came from the factory, there is no replacement and the watch will not be worn, etc.

Any watch that is going to be used regularly needs a white alloy spring -- carbon steel (blue) springs will almost always eventually break, and in doing so damage the train and jewels. This is a risk I'd rather not take. I've seen broken white alloy springs in wristwatches, but they were all from the 50's. Worn out, yes, broken modern springs, not so much.

Peter

 

[sderek]

Any watch that is going to be used regularly needs a white alloy spring -- carbon steel (blue) springs will almost always eventually break, and in doing so damage the train and jewels. This is a risk I'd rather not take. I've seen broken white alloy springs in wristwatches, but they were all from the 50's. Worn out, yes, broken modern springs, not so much.

Peter

I agree there may be a slight risk that a broken mainspring could damage a watch, after all, that's why the "safely pinion" and other features were introduced. But, I've been repairing watches for over 4 years, have changed countless broken mainsprings, and have yet to encounter a watch that was damaged by a broken mainspring.

 

[psfred]

Well, it's impossible to say with absolute surety that the broken jewels in a number of 17 and 21 jewel watches I've acquired in the last few years were broken by the back-lash from a broken spring, but when I take a watch apart and the third wheel plate jewel is smashed and the mainspring is broken on the arbor end (and if broken on the barrel end, no broken jewels) it's hard to believe it's a case of everyone slinging the watch into a wall when the mainspring broke.

I think alloy springs give better isochronism as well.

Broken jewels from a snapped mainspring isn't something I've seen in wrist watches, but then again, not only are the springs much weaker due to the smaller size, everything post WWII seems to have white alloy springs originally.

Peter

 

[Al J]

I don't normally see damage to the movement from broken mainsprings, although I'm sure it can happen. However for purely performance reasons I always change the spring in a watch I'm servicing, regardless what type is in there when it arrives at my bench. If I'm putting my warranty the job, I don't want to put any faith in an unkown mainspring. The cost of replacing the spring is usually pretty small in relation to the price of the service.

And although modern alloy springs are much less prone to breaking, I see broken modern springs quite often.

Cheers, Al

 

[Brad Maisto]

So it looks like the alloy mainspring is not set, but upon re-assembly, the watch still seems to have an "over-banking" issue and after looking in Fried's Repair manual, I'm not so sure I want to tackle what could be responsible for this to occur? It appears the balance pivot jewels are okay, so is there a possibility that the replacement alloy mainspring could be too strong causing it to overbank? I'm including some pictures with this post, as I ran into another problem when trying to put the watch back together. The small screw for the the re-attachment of the mainspring gear was useless, see the one picture. Luckily I had a parts SB grade 260 movement that had the same size screw available. I was beganing to panic that the re-assembly was going to be foiled by this broken screw.

It seems as though this watch was pretty highly finished at the factory, they even damaskeened both ends of the mainspring barrel. But i also noticed that there was a small amount of the barrel missing, it was where the cover re-attaches but even with this small piece missing, the cover seemed be attached securely. It was too difficult trying to get a picture of this. But thanks in advance for any further suggestions for me to get this watch working again.
Brad Maisto, Indiana Chapter 18 President

 

[Skutt50]

Here you can read some more about the shape of main springs and also a part of how to determine if a main spring is set: http://en.wikipedia.org/wiki/Mainspring

I am not sure what you mean with part of the barrel missing? You may on occation find a shaved off thin piece of material but as long as the lid attaches securley it should be fine! (I am not sure where this comes from but I guess it has something to do with watchmakers who istall the mainspring by hand and the sharp edges of the mainspring shaves a tiny bit of the rim of the barrel!)

If you have a well adjusted and newly serviced/oiled movement and install a new white alloy mainspring of the same dimensions as the old blue steel mainspring you may have an over banking issue. I have learned that the white alloy mainsprings are stronger than the old blue steel so you could try installing a mainspring some 2/100mm thinner to get rid of the banking problem.

You were lucky to get the old screw out. When they break it can be a bit trickey to reverse the broken part out of the threads!

 

[sderek]

So it looks like the alloy mainspring is not set, but upon re-assembly, the watch still seems to have an "over-banking" issue and after looking in Fried's Repair manual, I'm not so sure I want to tackle what could be responsible for this to occur? It appears the balance pivot jewels are okay, so is there a possibility that the replacement alloy mainspring could be too strong causing it to overbank? I'm including some pictures with this post, as I ran into another problem when trying to put the watch back together. The small screw for the the re-attachment of the mainspring gear was useless, see the one picture. Luckily I had a parts SB grade 260 movement that had the same size screw available. I was beganing to panic that the re-assembly was going to be foiled by this broken screw.

It seems as though this watch was pretty highly finished at the factory, they even damaskeened both ends of the mainspring barrel. But i also noticed that there was a small amount of the barrel missing, it was where the cover re-attaches but even with this small piece missing, the cover seemed be attached securely. It was too difficult trying to get a picture of this. But thanks in advance for any further suggestions for me to get this watch working again.
Brad Maisto, Indiana Chapter 18 President

This may be a terminology problem. A watch that is over-banking will continue to run, but sounds like it is galloping, because the balance wheel has excessive amplitude, and the roller jewel swings around almost 360 degrees and hits the pallet fork on the opposite side.

A watch that goes "out of action" will stop running because the roller jewel is on the wrong side of the pallet fork. Some refer to this condition as "over-banked".

So, does the watch have an "out of action" condition, or an "over-banking condition"? True over-banking (the watch continues to run) can be caused be too strong a mainspring, but if a watch is truly "out of action", then it's an escapement issue, and the pallet jewels, and/or the banking pins, and/or the safety pin (dart) needs to be adjusted.

 

[klevay]

A watch that is over-banking will continue to run, but sounds like it is galloping, because the balance wheel has excessive amplitude, and the roller jewel swings around almost 360 degrees and hits the pallet fork on the opposite side.

I was always under impression that condition you are describing is called "knocking"

 

[psfred]

Over-banking is a result of the failure of the safety pin to prevent the fork moving to the other banking while the impulse jewel is rotated away from the fork.

The general terminology, so far as I can tell by reading watch repair books, is that an "overbanked" movement is out of action with the fork on the wrong side of the fork. The condition where the impulse pin hits the back of the fork because the balance is rotating too far was known as "knocking".

Confusion between these terms may be a difference between how the conditions are expressed on the opposite side of the Atlantic, but all the older books I've seen call a watch out of action "overbanked" -- the use of the term to describe a watch with the impulse pin hitting the back of the fork seems to be a fairly recent event.

Either way, the impulse pin resting on the back side of the fork is a safety pin problem, possibly made worse by improperly set bankings or pallet jewel locking (hence the "overbanked" term -- bankings set too far inward result in lack of locking).

The impulse pin bouncing off the back of the fork due to over-rotation of the balance is far too much power in the watch or a serious miss-match between balance weight and hairspring.

Peter

 

[Brad Maisto]

SDerek, you stated:
"A watch that goes "out of action" will stop running because the roller jewel is on the wrong side of the pallet fork. Some refer to this condition as "over-banked".

So this South Bend is out of action and also thanks for all of the replys. I will let down the mainspring one more time and replace the balance and see if it will run with a very slight wind.

Thanks Again, Brad Maisto

 

[popechris]

I think this qeustion fits with this thread - my apology if I should have started a new one.

Context - I'm going to replace a blued mainspring in a Waltham 1894 12s (part 2224a) that I think is set. Considering a blued new old stock (NOS) vs modern. I can save quite a bit of coin with NOS, but

Here's my question - would a NOS mainspring that has been coiled in the packet for, say 75 years, also be set?

And what I was thinking (rationalizing?)- Maybe the winding and unwinding plays a role in setting, and NOS will be fine. Don't be such a cheap B..., this is watch making after all, buy a modern one.

 

[gmorse]

Hi popechris,

...would a NOS mainspring that has been coiled in the packet for, say 75 years, also be set?

I think that's highly likely, being continuously constrained in any way, whether in the barrel or in a NOS ring will produce the same effect. With old springs that have been in and out of the barrel, there's also the issue of coning, and with NOS, the risk of it simply shattering when released into the barrel.



David Boettcher's website on mainsprings is most informative.

Regards,

Graham

 

[Bila]

Here's my question - would a NOS mainspring that has been coiled in the packet for, say 75 years, also be set?

Actually not necessarily, I have seen plenty that have not been (and plenty that have been), but and it is a big but. Some steel used by some of the maker's does not seem to be of the quality it should be and you will get plenty of brittle ones that can even snap when winding them into a mainspring winder, let alone repeated winding in a spring barrel of a watch.

I myself would plum for a new Alloy spring, but again I have seen plenty of people not do so and not have a problem (and again, plenty that have had repeat breakages).

 

[Tim Orr]

Good evening, all!

I am not knowledgeable about mainsprings, but have to admit that I wonder why it is that there seems to be substantial agreement here that watch mainsprings can become ''set," but if we consider clock mainsprings, the consensus seems to be that they rarely can become so. What is different about watch and clock mainsprings that makes them so different?

Best regards!

Tim Orr

 

[penjunky]

upon re-assembly, the watch still seems to have an "over-banking" issue

Hi Brad

Just curious. Does the watch overbank when you wind it and begins to run, or is it everbanked before that? When you re-assembled and before winding does the balance wheel swing freely or just bounce back and fort on just one side of the fork?

The reason I'm asking is I have assembles some and didn't get the impact jewel in the center of the yolk and when I'd give the balance wheel a swing it would just bounce off the fork, no rotation. So now I make sure the impact jewel is in the center of the yolk before installing the balance wheel and cock.

Often times now, I wind the spring just a bit to hold the pallet fork so it doesn't move when installing the balance, and I place the impact jewel on the same side of the banking pin where the fork is resting.

I know you have installed the balance correctly but curiosity made me ask.

Good luck,,,Roger

Edit...I didn't notice the date you started this thread so assuming you got the watch fixed and running.

 

[Skutt50]

Often times now, I wind the spring just a bit to hold the pallet fork so it doesn't move when installing the balance, and I place the impact jewel on the same side of the banking pin where the fork is resting.

I think this is what most watchmakers do. Usually I turn the cock 90 degrees to get the impulse jewel way over to the correct side. When the cock is turned and put in place the impulse jewel will interact with the pallet form and the balance usually starts to oscillate.

 

[Dave Haynes]

I've seen both as noted above. The spring may be responding to cycles to make it set. How many times has it been wound and let run down. Military magazines apparently do not set if they are left compressed. They do deteriorate with hundreds of cycles of compress and rebound.

I wonder if there are high quality springs and cheapo springs? I have a drawer full of Sansteel blue springs and plenty of Waltham factory springs. I think Sandsteel was an American company and the Walham springs were made in France.

 

[penjunky]

I wonder if there are high quality springs and cheapo springs

Hi Dave

I bought a NOS steel alloy for a 16s elgin, took it out of the package and it was a long S. Put it in let the watch run down twice, two full winds. Just out of curiosity I took it back out and it stayed coiled, not much more than the blue spring I took out, no long S anymore. So maybe there is something to what you said, I wouldn't really know. Then again is a steel alloy already set just because it's a NOS?

Roger