Mainspring, Set OR Good?

[chris mabbott]

I’ve always operated under the assumption, mixed at times with fact, that a good mainspring, once released from its constraining collar, should have an S shape. This has been true for many of the blued type, and some alloy models.

Lately, I’ve had some MS, the new alloy types, that didn’t form the S shape, but, at least on 18 size, they have much resistance to winding, which is good.

I’ve also had a few in the 16 size, the resistance to winding, by hand, was barely evident. I’m wondering, some of these are NEW alloy MS, should these bet set so soon? Is it normal for them NOT to form the S, rather than the loosely unwound coil?

I’m changing one on a Waltham 16s, the old blue spring is set, and there is little resistance when I wind it by hand..
But on the same token, the brand new alloy job also appears “set” although not as tight as the old blue one. There is also not much resistance, as much as there should be in my imagination anyhow 🙄

Has anyone else experienced this with new alloy springs, if so what is the verdict…. Set or Sound?
If so, maybe we’re being too hasty in discarding the old “set” blue springs?

[willofiam]

Hey Chris, my first thought is mainspring strength by how it feels when winding may not be a proper way to determine the strength (maybe?), I would suppose run time would be a better way of gauging the strength. I have not heard of the S shape theory. Have fun , William

[bernie weishapl]

That is a hard one Chris. To me they are all weak especially after working on clocks with some of there mainsprings. 😆

[chris mabbott]

Gentlemen,

Bernie, you have to stop eating spinach pie buddy or you’re gonna tear those PWs apart 😆

William, S shape, or similar, is how a new MS is “supposed” to look in its expanded free form, mostly
What I usually do, while the MS is out of the barrel, I try to coil it by hand, form it into how it is supposed to fit in the barrel.. This should be impossible, or difficult to do with a new spring, or even some old ones, but on occasion, with a new spring, 16 size, I can do it, almost.

Just a little pre installation test I do for my own curiousity

[randy]

Most if not all of the new alloy ones I come across, I simply press in using the supplied holder.
But those that I’ve had to re-install for whatever reason, always have the “S” shape.
Just about all of the older blue springs I’ve come across are set to a point…some just aren’t as “tight” as others.
The strength/resistance you are feeling when you are winding them could be just the differences in tensile strength of the different alloys ???

RB

[chris mabbott]

That’s the mode of thought I was swinging towards Randy. Which leads me to wonder…. Have I missed a service bulletin about alloy springs 😆

You would think, or assume, that the “strength” when wound or during unwinding, would be the same as the steel. Obviously two dissimilar materials, but it’s the strength that should be compensated for by the alloy type….. You’d think?
So a wound spring of either material should have the same required power to drive?

So why do the new alloy springs, not all, feel weaker in hand, I wonder? 🙄

Just a PPSDTD 😆

[randy]

You would think so, yes..but hard to say given different heat treat methods ?
Oh man….A guy could stay up all night on this one !! 😯 🙄

[namonllor1953]

So is what I’m hearing is that, the mainsprings I purchased off ebay are not good?
They are blue steel because I read that, the white metal ones are from Europe and are weak but, the ones I purchased were not in the form of an S when taken out of their holder. They coiled when released from their holders but, were about three times wider than the set ones I took out of the pocket watches,and neither formed an S.
Thanks

[arutha]

Ren,
The only way you will ever find out for definite is to put the spring in and try it. If the spring is circular in shape and the coils tightly spaced then it will most likely be set but even so, some manufacturers used springs a little too strong for the movements which would keep them running even when they started to get a bit dirty.
I know this is on a bigger scale but on some smaller travel size clocks I have had no choice but to put back in the original spring(which was set) as you just can’t find a replacement and the clock has run perfectly. I have also had this happen recently with a Goliath pocket watch.
Maybe you can use a mathematical equation to work out what strength of spring is needed but there are too many variables for this to be a conclusive method, scored or mis-shaped pivots, scored jewels, wrong type of lubrication in certain areas, balance just fractionaly out of beat etc etc……..
Paul.

[randy]

Ren,
I think that it’s a crapshoot with the blue springs..that’s all.
I’ve purchased some good one’s and some not so good…..

[chris mabbott]

Hey Ren,

I think the rules are that there are no rules 😆

Let me say that…. In most of the books that have chapters on MS, that in some part, either pictorially or expressed, the S shape of a new, OR NON-set MS, is mentioned.
In MOST cases when I receive a blued or alloy MS, and removed it from the transport holder, they normally uncoil in the S form.. Well, not a perfect S but a kinda stylized one if you know what I mean..

New MS that remain in the coiled position are considered to be SET, but, they will also work to a point, you will not get a full run from the spring as it becomes weaker as it unwinds, even though the barrel design “should” compensate, as in going type, motor etc..

To date, with the ones I’ve received, 98% of the blued type have uncoiled in an S

About 95% of the alloy ones have uncoiled in an S shape. Obviously these are my own off the top estimates for illustration..

A new MS of either type material, that is being in the S shape, will be harder to coil than one that is set in the coiled shape, simply because we are coiling against its natural position.. So providing a more constant unwinding action, to a degree.

In my original post, I was wondering about the actual spring power of alloy.. Just to keep it easy and because I forget the actual numbers ill use a 1-10 scale

Lets say we need a 5 strength spring for our watch.. The original spring that is now set was blued steel and a 5 strength..

I have a replacement alloy spring (US Sold) that is basically the same dimensions and listed as 5 in strength..

But, when I remove the spring from the transport ring, it didn’t form the S shape. This is a new spring, so should not be set..

This is something I do just out of curiosity and not something that has to be done… I try to wind the spring with my fingers into its coiled form. With a good spring, there should be strong resistance to this, it should be impossible to hand wind this spring into the size of the barrel in which it will be placed (that’s why winders were made)
But with some of the alloy types, I can accomplish this, almost?

Whether these springs are sub standard, I’m not sure? But I’ll continue to monitor the ones I have.
I was curious as to the amount of people that have also experienced this with certain alloy types.. That they “feel” weaker, even when installed, the winding resistance feels less..

As Paul and Bernie mention, it’s a crapshoot LOL and difficult to find the “exact” spring.. Although if you measure the 3 key points of the old one (if it is original) you can pretty well nail it. There is also the calculation if no original spring is present, but this doesn’t take into account jewel count nor wheel material..

DISCLAIMER- this is NOT saying alloy is bad, just that SOME new ones I’ve had feel weaker than the old types I’m replacing..

Ren, I think, that some alloy MS are made in countries other than the US & Switzerland, maybe Asia, and Possibly,maybe, these springs in question are Asian in Origen? Which would make sense, although this is another assumption on my part.

Installing the spring into the barrel directly from the transport ring is fine, nothing wrong with it..
I got into the practice of not doing it that way simply because I like to confirm the length, thickness and see if it is set, etc and with some types of anchor point, you cannot install from the ring..

Thanks for the input guys, always appreciated

[chris mabbott]

Guys I was just replacing this spring, it’s a NOS Waltham alloy type, so gawd knows how old? I had to/wanted to remove it from the transport ring, simply because it was wound too large for the barrel.

Anyhow, here is what a “text book” good new spring should look like…. an S

• This reply was modified 3 years ago by Tamas Richard.

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