Buying a new main spring

[linux]

I'm still pretty much a rookie and practicing on movements.  I decided to work on removing and reinstalling a mainspring and while using a winder I broke the tab (is that called the bridal?) at the end while trying to get it into the winder barrel.  So I found a source for an NOS part but wonder how and where people order new alloy mainsprings?  I have the width, thickness and length of the broken spring but when I go to some sites there's a lot of different parameters that I'm not familiar with, things like 5/0, dennison numbers and pocketwatch numbers like 16, 18 sizes, etc.  The ms I broke is from an old ebay practice watch, and Elgin with a 412b movement that I never see in the tables.

Anyway I'd like to hear how you'all do it, thanks.

[AndyGSi]

This is a good document for mainsprings details.

https://www.jewelerssupplies.com/media/pdfs/MainspringsCatalog2018.pdf

[tcolgate]

CousinsUK have a tool for searching by size. With older springs there's also some variation in the bridle and the arbor hook. It's also worth checking out Alex Hamiltons video on sizing mainsprings by the barrel dimensions

https://youtu.be/BEfB8ZWoeII?si=-qYlhVoA3sY9pW2W

[praezis]

A mainspring is determined by 3 sizes only:

width, thickness, length. 
If you need to push it directly into the barrel and lack a winder: diameter

If your watch needs a special end other than the usual bridle: type of bridle.

I wonder why people still use such rubbish like Dennison sizes today .

Frank

 

[Neverenoughwatches]

10 hours ago, praezis said:

A mainspring is determined by 3 sizes only:

width, thickness, length. 
If you need to push it directly into the barrel and lack a winder: diameter

If your watch needs a special end other than the usual bridle: type of bridle.

I wonder why people still use such rubbish like Dennison sizes today .

Frank

 

I never know where i am with Dennison....with metric there's nothing at all to think about.

[JohnR725]

Dennison

13 hours ago, linux said:

The ms I broke is from an old ebay practice watch, and Elgin with a 412b movement that I never see in the tables.

One of the things always helpful in addition to a weird movement number is a picture of the watch. Because often times will look at the watch and say Oh one of those whereas we might not recognize it by the movement number. Or for instance?  While you do talk about pocket watches And pocket watch sizing you did not actually say whether this is a wristwatch or a pocket watch? Or where the movement number even came from?

 

11 hours ago, praezis said:

wonder why people still use such rubbish like Dennison sizes today

Because watchmakers over time adopted other people's stuff for their own. Over time watchmakers love all their different measurements with mainspring is being the most peculiar of often times having three different measurements all being used simultaneously possibly together. Oftentimes you'll see Dennison and inches and metric all at the same time.

So for those being confused with Dennison numbers I've attached a PDF cross reference chart.

Then if you really want to track down this Dennison Conspiracy I have a link to a PDF below.

https://theindex.nawcc.org/Articles/Watkins-MainspringGauges.pdf

13 hours ago, AndyGSi said:

This is a good document for mainsprings details.

https://www.jewelerssupplies.com/media/pdfs/MainspringsCatalog2018.pdf

What's interesting with the catalog is if you skip over everything and go back to the unbreakable mainsprings. You look at the interesting numbering scheme like MS obviously stands for mainspring. Then you get a number like 511 and that translates into the  with an thickness of the mainspring with the letter referring to the length. So Dennison appears to be alive and well in the modern numbering system.

Mainspring - DennisonChart.pdf

[praezis]

3 minutes ago, JohnR725 said:

So Dennison appears to be alive and well in the modern numbering system.

Not here, John. The same outdated rubbish like inches - says the continental European .

Frank

[Bonefixer]

A newbie myself, but I've said this before - don't waste money on Mainspring Winders. Get a new spring, or hand wind - if it was good enough for George Daniels I think it should be ok for the rest of us. 
 

For new springs I agree the Cousins search tool is the way to go. Sizing doesn't need to be exact - it has to fit in the barrel so if you can't find the exact size go a bit smaller and thinner. 

[AndyGSi]

16 minutes ago, Bonefixer said:

For new springs I agree the Cousins search tool is the way to go. Sizing doesn't need to be exact - it has to fit in the barrel so if you can't find the exact size go a bit smaller and thinner. 

Going thinner (or thicker) could effect the timing of the watch so best to stick with the original thickness and go shorter.

[Neverenoughwatches]

On 11/8/2024 at 9:32 AM, JohnR725 said:

Dennison

One of the things always helpful in addition to a weird movement number is a picture of the watch. Because often times will look at the watch and say Oh one of those whereas we might not recognize it by the movement number. Or for instance?  While you do talk about pocket watches And pocket watch sizing you did not actually say whether this is a wristwatch or a pocket watch? Or where the movement number even came from?

 

Because watchmakers over time adopted other people's stuff for their own. Over time watchmakers love all their different measurements with mainspring is being the most peculiar of often times having three different measurements all being used simultaneously possibly together. Oftentimes you'll see Dennison and inches and metric all at the same time.

So for those being confused with Dennison numbers I've attached a PDF cross reference chart.

Then if you really want to track down this Dennison Conspiracy I have a link to a PDF below.

https://theindex.nawcc.org/Articles/Watkins-MainspringGauges.pdf

What's interesting with the catalog is if you skip over everything and go back to the unbreakable mainsprings. You look at the interesting numbering scheme like MS obviously stands for mainspring. Then you get a number like 511 and that translates into the  with an thickness of the mainspring with the letter referring to the length. So Dennison appears to be alive and well in the modern numbering system.

Mainspring - DennisonChart.pdf 41.23 kB · 0 downloads

Whoa a 750 book watchmaker's library......now thats my kind of library.

24 minutes ago, Bonefixer said:

newbie myself, but I've said this before - don't waste money on Mainspring Winders. Get a new spring, or hand wind - if it was good enough for George Daniels I think it should be ok for the rest of us. 

George Daniels, probably the most skilled watchmaker of recent times.....have you watched him install a mainspring by hand ? .....10 seconds of pure art.  Neverenoughwatches hand winding a mainspring.......20 minutes of frustration and obliteration

[Bonefixer]

1 hour ago, AndyGSi said:

Going thinner (or thicker) could effect the timing of the watch so best to stick with the original thickness and go shorter.

For old watches I would err on the thinner side - don’t want too much power going through a 70 year old wheel train. Pretty sure I’ve read that somewhere and haven’t just made it up. 

[Neverenoughwatches]

1 hour ago, Bonefixer said:

For old watches I would err on the thinner side - don’t want too much power going through a 70 year old wheel train. Pretty sure I’ve read that somewhere and haven’t just made it up. 

yeah you wouldn't rev the gonads off of an old MK1 Cortina.

[JohnR725]

6 hours ago, Neverenoughwatches said:

Whoa a 750 book watchmaker's library......now thats my kind of library

Someday you have to take a trip to the BHI. If I can travel halfway across the planet to make it there you should Be able to somehow get there. The reason why you want to go it's a really interesting place and they do have a nice big library.

6 hours ago, Neverenoughwatches said:

Neverenoughwatches hand winding a mainspring.......20 minutes of frustration and obliteration

What is interesting In watch repair is all sorts of examples of how other people don't need the tools and the rest of us will use the tools. There is a reason why there so many mainspring tools even if George Daniels can wind Them by hand in his sleep in the dark.

Just because somebody else does it doesn't mean you should do it.

One of my favorite was I was once looking at examples of how watchmakers are supposed to sit at their bench and found all these bizarre examples of well how I guess we should do it because we find someone else doing it we should emulate that. My favorite was somebody sitting at a standard desk the entire desktop was covered with stuff probably valuable stuff holding the watch in his hand. Demonstrating we don't need a watch bench or movement holder because that's what the person was Doing.