winding mainspring into barrel by hand

[Bill2024]

  On 3/12/2025 at 11:30 PM, AndyGSi said:

Most new mainspring come in a washer used to insert into the barrel without needing a winder.

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Thanks - I have bought a new mainspring which, as you say, came in a washer. I haven’t tried installing yet though. 

  On 3/12/2025 at 10:21 PM, RickTock said:

These 3D printed mainspring winders have become my go-to. My nice Chinese set with steel arbours is just collecting dust.

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They do look interesting - on the eBay listing it makes reference to using a specific type of staples which may not be available in the UK. Will look into these more though. Thanks for the heads-up. 

[Neverenoughwatches]

  On 3/12/2025 at 11:23 PM, Bill2024 said:

I will look out for Bergeon winders but I probably can’t justify the cost (even for just a few of them) just yet.

Mostly I will try to clean and reuse mainsprings. If a new one is needed however, I found an interesting article/video on watchrepairtutorials about sizing a generic mainspring to a barrel if you can’t get the exact one for whatever reason. 

https://watchrepairtutorials.com/how-to-size-any-watch-mainspring-to-a-barrel/

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Alex's first option really threw me, and to suggest that wear in a movement unvaluable or not to me, can be compensated for by supplying more energy from using a stronger mainspring goes completely against my thinking. Would someone install a higher horse powered engine in a car to overcome wear friction in its gearing and running systems to make it go faster ? Maybe if they wanted to shake the car to pieces. More torque from a stronger mainspring will exacerbate  the wear conditions associated with the original lack of power, and create wear in places that wasn't already there. There may not be another option for the repairer at that moment in time, but that option will lead to a much larger repair job fairly quickly.

Again I don’t fully understand this. These two paragraphs appear contradictory.  In the first instance there are over one hundred different sized mainsprings for a set barrel diameter, yet Alex's single formula is used to calculate the strength and length. I wasn't sure what dimension Alex was asking for here, total internal area, internal free area with an arbor fitted,  or internal diameter. Only one dimension will change, the one with an arbor. His example... every 11mm barrel will calculate to the exact same strength and length spring. Sorry Alex your formula appears to make no sense.

As regards to the first statement - what this should be telling you is that there is no exact science- .  What it tells me is that there are many variables between movements that have 11mm barrels and that calculating the mainsprings for them is an exact science based on these variables.

The arbor isn't factored in, I dont get it

Edited March 13 by Neverenoughwatches

[mikepilk]

  On 3/12/2025 at 11:23 PM, Bill2024 said:

I will look out for Bergeon winders but I probably can’t justify the cost (even for just a few of them) just yet.

Mostly I will try to clean and reuse mainsprings. If a new one is needed however, I found an interesting article/video on watchrepairtutorials about sizing a generic mainspring to a barrel if you can’t get the exact one for whatever reason. 

https://watchrepairtutorials.com/how-to-size-any-watch-mainspring-to-a-barrel/

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I have a small set of winders I bought from ebay. Keep a watch for them, you don't need a big set.

The GR database is useful for looking up mainspring sizes : GR Mainsprings.pdf

And here is a spreadsheet I copied for calculating spring size. (I cannot attach xls files, so download and change the extension to "xlsx")MainspringCalculator .pdf

 

Edited March 13 by mikepilk

[tomh207]

@Neverenoughwatches

its all clear as mud Rich.

looking at stuff that is considered cannon, abor = 1/3 barrel id, spring horizontally = 1/3 barrel id leaving free space equal to 1/3 of barrel id. In this it has to be a rule of thumb which at the scale approximates for barrel floor area. 
 

So thinking about this I see some possibilities towards defining it but my maffemattix is not up to it. However as a starting point the arbor hook is there to be measured, as is the barrel id. The thickness (strength) will be determined by the measured height of the arbor hook. From there the remaining bit should be determined by length of spring = 1/3 barrel floor area divided by arbor hook height.

I’m probably way off and oversimplifying it. We have some very clever people here, maybe they can expand and/or correct any of my ramblings.

 

Tom

[mikepilk]

  On 3/13/2025 at 10:23 AM, tomh207 said:

I’m probably way off and oversimplifying it. We have some very clever people here, maybe they can expand and/or correct any of my ramblings.

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Have a look at the spreadsheet I posted above

[Neverenoughwatches]

  On 3/13/2025 at 10:23 AM, tomh207 said:

@Neverenoughwatches

its all clear as mud Rich.

looking at stuff that is considered cannon, abor = 1/3 barrel id, spring horizontally = 1/3 barrel id leaving free space equal to 1/3 of barrel id. In this it has to be a rule of thumb which at the scale approximates for barrel floor area. 
 

So thinking about this I see some possibilities towards defining it but my maffemattix is not up to it. However as a starting point the arbor hook is there to be measured, as is the barrel id. The thickness (strength) will be determined by the measured height of the arbor hook. From there the remaining bit should be determined by length of spring = 1/3 barrel floor area divided by arbor hook height.

I’m probably way off and oversimplifying it. We have some very clever people here, maybe they can expand and/or correct any of my ramblings.

 

Tom

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I like to always check the mainspring size of any movement I am working on, often just out of curiosity.A cross check using the rule of thirds and by halves.

[Bill2024]

  On 3/13/2025 at 9:05 AM, mikepilk said:

I have a small set of winders I bought from ebay. Keep a watch for them, you don't need a big set.

The GR database is useful for looking up mainspring sizes : GR Mainsprings.pdf

And here is a spreadsheet I copied for calculating spring size. (I cannot attach xls files, so download and change the extension to "xlsx")MainspringCalculator .pdf

 

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Thanks for the info.

  On 3/13/2025 at 9:05 AM, mikepilk said:

Keep a watch for them

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I see what you did there!

[Bill2024]

  On 3/13/2025 at 5:18 AM, Neverenoughwatches said:

Alex's first option really threw me, and to suggest that wear in a movement unvaluable or not to me, can be compensated for by supplying more energy from using a stronger mainspring goes completely against my thinking.

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Totally agree. That just seems completely counterintuitive as, to my mind, this is just going to exacerbate any ware issues in the movement.

Regarding the formula for working out the mainspring size form barrel measurements I would say that, as a newcomer to all this, I tend to take things at face value from what I regard as a reliable and knowledgable source.

Seemingly there is more to it though; but maybe the formula is close enough to get you out of a situation if you can’t find the correct spring from a data sheet? Or maybe the formula is useful as a starting point which can be refined with experience?