How to get pocket watch mainspring

[Sven]

Hello,
This is a 690 x 2 x 0,20 mainspring I found broken in a Rosskopf pocket watch with holes in both ends.
I've tried with cousins but they say they don't have it.

If you have tips for me how to do this ... most welcome

[clockboy]

I will look in my mainspring draw if no luck but out most of today. i will watch this space.

[oldhippy]

There's many watch materiel supplies on the internet and have you tried ebay. 

[szbalogh]

Roskopf (or Rosskopf) pocket watches have low end movements. I am sure You can find one selling for parts. 

[vinn3]

yes,  a parts watch.   you can collect them,  all part of the hobby.  vinn

[clockboy]

12 hours ago, Sven said:

Hello,
This is a 690 x 2 x 0,20 mainspring I found broken in a Rosskopf pocket watch with holes in both ends.
I've tried with cousins but they say they don't have it.

If you have tips for me how to do this ... most welcome

Hi I have looked through my mainspring draw but nothing like what you require. The pocket mainsprings I have in stock have a bridal end not a hole end. I have used this guy to purchase job lots of watch mainsprings. He has listed here some pocket mainsprings but if there are any with holes both ends is not known.

http://www.ebay.co.uk/itm/Lot-40-Vintage-Swiss-pocket-watch-mainsprings-15-to-22-ONLY-4-WATCHMAKERS-/351816068979?hash=item51e9df2f73:g:TucAAOSwbsBXpR4h

[JohnR725]

For future reference mainspring Size numbers are listed as  Width x Strength x Length. Then depending upon where you are the numbers are either metric inches or Dennison or some combination of all three.

So if you look on the cousins website they make reference to a mainspring catalog with the name of Generale Ressorts Which is very handy when you're looking for things like this. So I'm going to give the numbers out of the catalog of anything that's close.

Then blue Springs versus White Springs? Usually blue old White/silver is usually modern and the modern Springs are usually stronger for the same thickness. So this opens up possibilities you don't have to have a spring of the exact thickness especially a watch of this quality. Then you can go slightly narrower for the width. The end definitely a problem for something unusual but a hole only requires a punch. In the absence of the actual mainspring punching pliers we should Be able to figure out something if you can get a spring close.

So the problem is we can get a width of 2 mm or 1.9 mm which is acceptable what's the problem is there either way too short almost nothing that's really close and a few that are too long which can be shortened.

So for 2 mm width we get the following

5850  0.165  700 mm

5877  0.185  700

5879  0.185  840

so now I dropped to 1.90 mm for the width

5587  0.16  680 mm

5630 0.18  700

 

 

 

 

[clockboy]

I agree the spring does not need to be the exact size providing it is not to high.However the problem Sven has is the spring he requires has holes/slits at both ends. I did not know how to make a slit shape hole on a watch mainspring without distorting it. However I have done some research this morning & it appears it can be done. First you need to anneal the spring end that requires the hole/slit & then either punch to drill the hole. But the I presume you will need to harden the spring again. I found this tool on the net but I don,t know how small the holes slits are that it makes.

 

[JohnR725]

I have attached additional images showing you the mainspring punch pliers. You'll notice that the pliers have a secondary use which is if the hook breaks off in the barrel it can be used to make a new one of those.

Then clockboy brings up something interesting the references I have are you need to anneal the end of the spring but nothing about hardening the spring afterwards? It's possible you don't actually have to harden the end. Typically if you look at American blue mainsprings the center hole is not hardened. Which comes in handy if you have to re-shape that section to hold better. Unlike modern Springs where the entire spring is very hard.

[clockboy]

I am so sure on the not re-hardening . On a pocket watch the the idea of the end hole is to stop over-winding of the mainspring but if a user gives a bit of extra force every time it is wound the end hole will start to split & elongate.

If this was my project as an experiment I would anneal the end of the broken spring & drill & file the slit to the correct size. I would then re-harden by heating and cooling in cold oil to avoid the metal splitting.

[JohnR725]

So I've attached the text that goes with the image of the players. Notice they reference a stop mechanism so you can't rip the end off which I find amusing because quite a few American watches such as Waltham Have mainsprings with hole in and and they typically don't have stop works.

[Marc]

53 minutes ago, clockboy said:

I am so sure on the not re-hardening . On a pocket watch the the idea of the end hole is to stop over-winding of the mainspring but if a user gives a bit of extra force every time it is wound the end hole will start to split & elongate.

If this was my project as an experiment I would anneal the end of the broken spring & drill & file the slit to the correct size. I would then re-harden by heating and cooling in cold oil to avoid the metal splitting.

I agree that leaving the end of the main spring in its annealed state could lead to problems with the steel being too soft to be durable. However if, following annealing and punching the end of the main spring, you then re-harden the end by heating and then quenching, would it not then be necessary to temper the re-hardened part of the spring?

Typically spring steels when simply hardened become very brittle and need a degree of adjustment by re-heating to a specific temperature, traditionally gauged by observing the oxidation colours that vary according to temperature, in order to achieve a balance between hardness and durability appropriate to the intended application of the steel.

I had always assumed (rightly or wrongly) that the blue colour of of the older blue steel main springs was the result of the tempering process.

 

Temperature		Color of Heated Carbon Steel
(oF)	(oC)
600	316		Scrapers, spokeshaves
560	293		Screwdrivers, springs, gears
540	282		Cold chisels, center punches
520	271		Taps <= 1/4 inch
500	260		Axes, wood chisels, drifts, taps >= 1/ inch, nut taps, thread dies
480	249		Twist drills, large taps, knurls
460	238		Dies, punches, bits, reamers
450	232		Twist drills for hard use
440	227		Lathe tools, scrapers, milling, cutters, reamers
430	221		reamers
420	216		Knives, hammers

[clockboy]

This post is becoming interesting & this is what this forum is really good at.
I don,t know for certain if my idea would work that is why if me I would do a test on a old spring or the broken one so if it does not work no un-revearsable damage has been done. I do know my brother-in law repaired a clock spring using my method.
But this is the fun of horology you will never stop learning.

[Geo]

Here's my tuppence worth guys.

I have repaired a few springs that I couldn't get replacements for by using the Tissot tool described above by CB.  For best results when punching the hole, leave the spring in it's hard state as this ensures a clean and accurate hole.  Once the hole has been punched, I soften the end of the spring to allow me to accurately shape the curl for the arbour.  I have not had any problems with springs that have a soft arbour curl.

I do not attempt to re-temper the end, as to I would have to temper the whole spring to ensure evenness of temper throughout the entire Spring length.   If you try to harden and temper only the end curl, there is a good chance that you may reduce the temper of the spring further into the main curl.

I have tempered springs completely and use this method.  First I heat the spring to cherry red then immediately quench in water.  Once glass hard I carefully apply grease to the spring ensuring total coverage.  The spring is now dipped in a bath of molten lead that I have set at the correct tempering temperature using a infra red thermometer.  Using this tequnique, it is impossible to go beyond the correct tempering temperature.  The application of grease prevents lead soldering itself to the spring.

[Sven]

Thanks you all very much for all the info !

I read that breaking of the mainspring on those watches was a common problem, so I thought is was easy to replace but it appears it comes a little more challenging  

The hook on the end is there to fit with the little mainspring part fixed in the barrel "Philippe drag spring" - see the attached picture from http://www.musketeer.ch/watches/roskopf.html .

I will see I can get a mainspring puncher tool somewhere (The one on the pictures above is Bergeon 30539 I think) and I'll order piece 5877 as suggested by John above.

So procedure would be:

     (1) anneal - heating to red and slow cool down

     (2) punch

     (3) temper - heating to blue and oil cooling

 

When this doesn't work out I'll go for a sacrificial parts movement, but as the breaking of the spring is common I fear that it will come with a broken or weak mainspring so I would prefer to get in a new one.

I'll let you know how this adventure will end.