Jump to content
  • 0

Mainspring for pocket watch


Extractor
 Share

Question

After having experimented with some very cheap watches I thought it was time to attempt something a little nicer. Bought this silver pocket watch and took it apart. Noticed quite a few of the jewels were shattered so is likely to be beyond my skill set at the moment to restore anyway. Despite that, I decided, probably unwisely, to examine the mainspring and measure it up for a replacement so rendering it useless in the process.

The measurement I have taken are: 

  • Height: 2.6mm
  • Thickness 0.2mm
  • Length: 520mm
  • ID of barrel: 16.5mm
  • Type TR

Then I find out there is no replacement to be found in the TR book which I accessed through the Cousins website. Am I not looking properly or have I made a big mistake in assuming a replacement could be found?

Many thanks.

IMG_20210115_184200[1].jpg

IMG_20210122_153041[1].jpg

Link to comment
Share on other sites

18 answers to this question

Recommended Posts

  • 0

Cousins lists a GR 6801, 2.60 x 0.20 x 540 16.5, that would work perfectly. It has a normal "tongue end", which will work fine with the hook in your barrel.

Link to comment
Share on other sites

  • 0
19 minutes ago, Extractor said:

After having experimented with some very cheap watches I thought it was time to attempt something a little nicer. Bought this silver pocket watch and took it apart. Noticed quite a few of the jewels were shattered so is likely to be beyond my skill set at the moment to restore anyway. Despite that, I decided, probably unwisely, to examine the mainspring and measure it up for a replacement so rendering it useless in the process.

The measurement I have taken are: 

  • Height: 2.6mm
  • Thickness 0.2mm
  • Length: 520mm
  • ID of barrel: 16.5mm
  • Type TR

Then I find out there is no replacement to be found in the TR book which I accessed through the Cousins website. Am I not looking properly or have I made a big mistake in assuming a replacement could be found?

Many thanks.

IMG_20210115_184200[1].jpg

IMG_20210122_153041[1].jpg

You can never be sure that the mainspring that is currently fitted is the right one. Check what size is needed for this caliber first, or measure the depth of the barrel and subtract 0.1mm to verify is 2.6mm is right.

Link to comment
Share on other sites

  • 0
23 minutes ago, Poljot said:

You can never be sure that the mainspring that is currently fitted is the right one. Check what size is needed for this caliber first, or measure the depth of the barrel and subtract 0.1mm to verify is 2.6mm is right.

Ah, that opens up quite a few more possibilities. The barrel depth is 3.4mm so it can be a considerably wider mainspring as long as I stay within 3.2mm to build in a little safety margin. You are right that the current mainspring almost certainly was not the correct one.

 

 

Link to comment
Share on other sites

  • 0
Just now, Extractor said:

Ah, that opens up quite a few more possibilities. The barrel depth is 3.4mm so it can be a considerably wider mainspring as long as I stay within 3.2mm to build in a little safety margin. You are right that the current mainspring almost certainly was not the correct one.

 

 

Exactly!

However, 3.4mm seems to be very deep, are you measuring correctly? What is the movement?

Link to comment
Share on other sites

  • 0
35 minutes ago, nickelsilver said:

Cousins lists a GR 6801, 2.60 x 0.20 x 540 16.5, that would work perfectly. It has a normal "tongue end", which will work fine with the hook in your barrel.

If the exact spring cannot be found, in what order of importance would you rate the different parameters? I would have thought that the type, height and ID of the barrel are absolute requirements. Thickness and length less so?

Link to comment
Share on other sites

  • 0
7 minutes ago, Extractor said:

If the exact spring cannot be found, in what order of importance would you rate the different parameters? I would have thought that the type, height and ID of the barrel are absolute requirements. Thickness and length less so?

Strength, height, length.

Link to comment
Share on other sites

  • 0

I have measured with the depth gauge of a Mitutoyo caliper, resting the the base on two sides of the curvature, allowing the depth probe to reach the bottom, keeping it as parallel as I could manage.

Link to comment
Share on other sites

  • 0
3 minutes ago, Extractor said:

The main reference I can find is 'The Semloh Lever' and '999' which, after some searching has led me to this:

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&Cyma_999

And:

https://www.watchuseek.com/threads/another-pocket-watch-incoming.4975015/

Looks quite similar. Holmes spelt backwards? What on earth....?

IMG_20210115_184237[1].jpg

Well, then here is your mainspring: 2.95 x 17.0 x 0.19mm

Link to comment
Share on other sites

  • 0
Just now, Extractor said:

I have measured with the depth gauge of a Mitutoyo caliper, resting the the base on two sides of the curvature, allowing the depth probe to reach the bottom, keeping it as parallel as I could manage.

Right, you are measuring to the top edge - do not forget that barrel lid takes some space also.

Link to comment
Share on other sites

  • 0

2.80 x .205 x 600 x 18 TR- End

GR7002TR

58 In Stock

£7.30

This is probably as good as it gets for TR end from what is available on Cousins site.

Link to comment
Share on other sites

  • 0
1 hour ago, Poljot said:

2.80 x .205 x 600 x 18 TR- End

GR7002TR

Almost, but not quite. The 18 is too big as barrel ID is only 16.5mm (17mm on the reference sheet linked above so my measurement is likely to be 0.5mm off).

2 hours ago, nickelsilver said:

Cousins lists a GR 6801, 2.60 x 0.20 x 540 16.5, that would work perfectly. It has a normal "tongue end", which will work fine with the hook in your barrel.

With TR springs being difficult to find, would a DBH not work better than a normal bridle? I am thinking that the hook at least has a hole to engage in?

Link to comment
Share on other sites

  • 0
1 hour ago, Extractor said:

Almost, but not quite. The 18 is too big as barrel ID is only 16.5mm (17mm on the reference sheet linked above so my measurement is likely to be 0.5mm off).

Do not be concerned about 16.50mm Vs 17.00mm. All it means that you will not be able to push it in, but nothing stops you from using a mainspring winder, or your fingers to install the mainspring. 2.8 is way better choice than 2.6 for your deep barrel.

Link to comment
Share on other sites

  • 0

I have found GR7087 which is 2.90 x .19 x 520 x 16 is stock at Cousins which is probably as close as I will get. Many thanks Poljot and Nickelsilver for your kind advice!

Link to comment
Share on other sites

  • 0

The Generale Ressorts book specs the GR 7070 for this caliber, 2.90 x 0.175 x 500. Cousins has 87 in stock at a whopping 7.30 GBP. Dang, I get my springs directly from GR and they are always 25 CHF and up!

Link to comment
Share on other sites

  • 0

The Otto Frei web site carries mainsprings as well, categorized by end-type, strength/thickness, height, and length.  If you should ever have trouble getting the spring you need at Cousins (which I think would be rare) then Otto Frei is a handy back-up.

 

Link to comment
Share on other sites

  • 0

@nickelsilver,

do you get Inox or Nivaflex from GR? Price of N. is a multiple of I.! Cousins sells Inox.

Frank

Link to comment
Share on other sites

  • 0

Looks like it was made in St. Imier, excellent watch. I wouldn’t worry to much about the jewels I bet you it’ll keep good time anyway. You can change them at a later date ?

Link to comment
Share on other sites

 Share



  • Similar Content

    • By PaulnKC
      Greetings All,
      Hope that all are doing well - in this crazy COVID world.
      I recently acquired a 1958 Rolex Ref. 6569 with a Cal. 1030 movement. All-in-all very nice and clean for her age - and runs very well.
      The winding pinion and clutch wheel had worn each other out - so I found NOS Rolex parts and replaced those. I though the watch deserved the new parts.
      It appeared to have been serviced in the last 10 years - because everything looked clean and the oil looked good (and present).
      Since the watch seemed to be running well and in good health (other than the winding pinion and clutch wheel) - I didn't do a complete service. I didn't think it was worth the risk.
      However, it seems to me that the watch is harder to wind than I would expect.
      I did do a full service on a 1215 that I bought for my wife (ref. 6694). It needed everything - but an awesome running movement when I was finished.
      The 1215 is of course a manual wind - but similar to the 1030. The 1215 winds lightly and smoothly as one would expect.
      The 1030 is "stiff". I haven't taken the barrel apart - but have just ordered some new mainsprings.
      Is there anything tricky about replacing the auto mainspring in a 1030? Or is more or less like any modern auto?
      Clean the barrel; apply braking grease to wall; fit spring; fit arbor - oil lightly at spring-arbor interface; replace lid?
       
      Also - I was only able to find a parts-list for this movement. Anyone know where a tech/service sheet (or similar) may be found?
       
      Thanks in advance for your suggestions.
      -Paul
    • By Zero
      I'm interested to learn the definition of a pocket and a wristwatch mainspring, in terms of dimensions.
      1) What is the general height range for a wrist watch mainspring? Eg. 1mm to 2mm
      2) What is the general diameter range for a wrist watch mainspring? Eg. 7mm to 12mm
      3) What is the general height range for a pocket watch mainspring?
      4) What is the general diameter range for a pocket watch mainspring?
      5) Is the mainspring eye/hole size generally half the height of the mainspring?
      Reason: I'm looking to classify them correctly for improving the rs winder project releases.
      Will appreciate any help.
    • By Max50916
      Forgive me if this is a dumb question. I'm currently working on an AS 1187 1194 movement which has a broken mainspring. I have a bunch of NOS mainsprings and would prefer to use one of possible. After looking into it, it seems the proper mainspring size for this movement is Denn. 6 x 11 -- 11.5
      I've got ones close to that but not exactly that. So my question is, is it possible to use a mainspring with a slightly different width, strength, or length?
      Is there more wiggle room in regards to any measurements in particular? (by that I mean, maybe there is no wiggle room in width but some wiggle room in strength etc) 
      I've attached some photos with ones that seem to be relatively close, and am wondering your thoughts on using any of them? This is for a personal project so I'm looking to spend as little money as possible, otherwise I would buy a new mainsprings from Jules Borel.
      Thank you for any help you can give!




    • By richiesgr
      Hi
      I'm trying to figure out how to reassemble this mainspring the mouvement is Felsa 4017N . I join photo
      As you can see the arbor seems to be sealed on the wheel I tried to free him but there are some dents that prevent this. It seems to be one piece. 
      I've replaced replace the spring into the barrel but can't place the arbor in place ???⁉️
      Thanks for your suggestions
       


    • By Graziano
      Quite a rare old watch lever set 18s running very well. 
      Location: Philadelphia, Pennsylvania
      Years of Operation: 1868-1886
      Production Jewels: 7-19 Jewels
      Production Sizes: 18s, 16s, 8-6s
      Total Production: ~12,000
      Factory Building Status: Demolished



  • Recently Browsing

    No registered users viewing this page.

  • Topics

  • Posts

×
×
  • Create New...