Let's talk Mainsprings

[Fraczish]

As a hobbiest (currently) I've take a movement apart and reassembled it a couple of times now. I've always stopped short of removing the mainspring as I don't have a winder. 

So I have a couple of questions...

1, how would I go about ordering a new mainspring? Assuming originals for many of my vintage pieces will not be available.

2, in respect of a Winder, as a hobbiest what might suit my needs? I've seen a set on cousins that go for around £175. Do I need all these?

Many thanks always guys :-)

[rodabod]

1. Look up a genrale ressorts catalogue for a size reference. Failing that, measure the old one.

2. I'd keep hand winding in the meantime. You have to be really ham-fisted to distorted them. Used sets turn up on eBay occasionally.

[Fraczish]

Thank you Rodabod. When measuring for a mainspring is it just the uncoiled length and width to consider? One site I looked at talked about a strength value and a diameter?

[rodabod]

The "strength" sometimes an older term refers to the thickness. It is critical, whereas length is not absolutely critical. The reason is because the force developed follows a cube rule relative to the thickness. Ideally you'd use a micrometer, but a decent vernier caliper may suffice.

[Fraczish]

Thanks again that's really useful to know going forward.

I've looked through the GR book and found the mainspring for my watch. Where would I actually source one from? Either genuine or generic?

[Fraczish]

Got a few from Cousins. 

Is there anything specific I should know/do during installation? My Intention was to use Molykote DX on the barrel wall. I believe the spring will be pre-lubricated is that right?

I have read somewhere on here about often  having to manipulate the hook end of the MS, not sure Mark covered this in the chapter, could be wrong though. And advice would be great as always. 

[watchweasol]

The hook end of the mainspring, the outer end has attached a small tongue which will auto locate in the anchor position by means of a stop on the barrel wall,     automatics have a bridle spring attached which locates against the barrel wall and slips when under max tension so as not to break the spring, hence the breaking grease on the wall. The details given by Rodabod  are spot on  usually    Height X  Thickness  X  Length X   Barrel diameter. 

[Fraczish]

Thanks watchweasol. The course has not covered Automatics yet, not sure if it does in Level 3. I was aware of the the slipping action as a basic concept from reading threads on here, haven't had one apart yet. 

Edited May 27, 2020 by Fraczish

[rodabod]

3 hours ago, Fraczish said:

Got a few from Cousins. 

Is there anything specific I should know/do during installation? My Intention was to use Molykote DX on the barrel wall. I believe the spring will be pre-lubricated is that right?

I have read somewhere on here about often  having to manipulate the hook end of the MS, not sure Mark covered this in the chapter, could be wrong though. And advice would be great as always. 

Usually you can just push the empty barrel cover over the new spring and it will slip in with a little coaxing. Remember to get the orientation correct. 
 

Lubrication - depends if it’s an auto like WW says. New springs are sold with a lubricant film on them, but I also add more anyway as I don’t see the harm, plus some stock is quite old. 

[JohnR725]

3 hours ago, Fraczish said:

My Intention was to use Molykote DX on the barrel wall

Generic conversations on mainsprings can be an issue? Like using the term Vintage is interesting like what kind of vintage? So typically on mainsprings you need the with, thickness or strength and length. Then it depends on whether We are talking about a Swiss or American mainspring as mainsprings are interesting they can be measured in inches, metric and Dennison and conceivably the package will have all three. Then if it's vintage the end of the spring is important because the ends may be different depends on what were looking at.

Then mainspring lubrication if the mainspring is the normal new either prelubricated or made out of a material a proper steel that doesn't need lubrication no lubrication is required including on the barrel wall. Unless of course it's an automatic mainspring Then your lubrication choice would be very very bad for that. So typically all you'd need to do is lubricate the arbor. Unless It is an automatic then Some form of breaking grease will be required and of course lubrication of the arbor.

Then if we want to be generic about this if you know what the watch is you can look up what mainspring supposed to be in their. If it's a vintage watch there may be no listing  then you have to take it out and measure it. If it's a standard Swiss mainspring usually can just push it in you don't need a Winder.

[mooseface]

Mark Lovick has posted an excellent video on mainspring choosing on Youtube. Worth a watch if you'll excuse the pun.

 

[Fraczish]

Thanks John,

I have managed to look up the correct MS for the watch I'm working on (peseux 180) manual. Apologies for the confusion, when I said I ordered a few, I ment I've ordered a couple for watches I intend to service in the coming weeks. So I'm fairly sure I've got the right one. 

Thanks for the tips about not greasing the barrel wall. I for some reason thought Marks lesson advised to, I've likely got that mistaken. 

The end I believe is "normal" type

Edited May 27, 2020 by Fraczish

[Fraczish]

8 minutes ago, mooseface said:

Mark Lovick has posted an excellent video on mainspring choosing on Youtube. Worth a watch if you'll excuse the pun.

 

Brilliant thanks, I will definitely watch that one

[AdamC]

One website I use regularly to find suitable mainsprings for the vintage watches I service is https://www.vintagewatchstraps.com/mainsprings.php. Very useful explanations and calculators that I use so either when you can’t identify a movement to look up a mainspring or when one isn’t available from the materials house. I can work out a suitable size by measuring the internal diameter of the barrel and external diameter of the arbor. Ideally you’ll have the old spring to measure the thickness (strength) but even without one, one of the calculators can estimate the correct thickness. It also helps as a way to verify if the old spring was in fact the appropriate one as past servicers have been known to fit a “near match”. The Ranfft website also has mainspring data for most vintage watches. Hope that helps for future reference.

 

 

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