Jump to content
  • 0

Mainspring for pocket watch


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 post
Share on other sites

15 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 post
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 post
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 post
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 post
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 post
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 post
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 post
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 post
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 post
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 post
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 post
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 post
Share on other sites


  • Similar Content

    • 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



    • By thecodedawg
      I recently acquired an Illinois pocket watch that appears to have a screw on front and back. I was able to unscrew the front with great effort.  A lot of dirt and grime dropped out.  I need to get the back off.  There are no grab points so, I have tried a rubber ball and failed.  If it was a bolt, I would use heat, but that’s not an option.  I am afraid to use penetrating oil for fear of damaging the porcelain face.  I am assuming that the watch is in the 100 year old range but won’t know until I get the serial number off the movement.  
       
      it is clear, the case has not been opened in a very long time.
       
      What is the best way to open it?
       
    • By GoMSUSpartans
      Looking for advice.  Daughter (7) bought me a pocket watch from a second hand store.  The hunter case crown is missing a cap to open the front. It appears to be threaded.  Essinger seems to have the right replacement part. I can't figure out how to get the stem and crown out. I think this is an old Belle Suisse 8810. Help?  Also I know it is posted to wrong forum but this was the only non grayed out option.

    • By Colditz
      I too have a Longines 7084460 with broken mainspring. What would be the correct replacement spring for it and do Cousins do one.? The number is engraved on the movement. This number is engraved inside the case back. 23204 114
       
      Thanks guys.
    • By Mazboy
      I am working on a Bulova 11 BLC movement and trying to source a new replacement mainspring, does anyone know where i may be able to source one?
  • Recently Browsing

    No registered users viewing this page.

  • Topics

  • Posts

    • I think Earl Gray is an acquired taste. I hated it when I first tried it. Now I find it tolerable. Eventually I might find it ok. 😂 But what do you think of tea used in confections and other foods. Like matcha cakes 😖, Earl Gray cheesecake 🤪, duck smoked with tea leaves 🤔, etc...?
    • Hello Not really a watch question, however I thought I would it it a try. I have a couple of Silver Beer Mugs that are tarnished and all I have to clean them with is the L & R Ultrasonic Watch Cleaning Solution (ammoniated) and a ultrasonic machine. I also have the L & R Ultrasonic Watch Cleaning Solution and an Ultrasonic machine. Does anyone know if I can use these two products on the silver beer mugs or should I get another type of cleaner> Also should I be diluting the cleaning and rinse solutions?  Thanks in advance for any help that can be provided. Michael
    • Hi JDM - Thanks for the detailed reply. The Bezel only looks like a rotating time ring, but it's just a "faux" divers watch, only rated to 50m. I think the Seiko "Solar Power" version actually had a rotating ring and Tritium on the hands and numbers and was rated to 200m or something. But, the bezel is fixed. Also, there are no "indent" or any indication that you could use a Snap Back knife to open the bezel. If this is not indeed a screw off bezel (using a screw type base wrench), then a 4 blade bezel tool is likely the only thing that will remove it. Then I'll need to figure out how the stem is removed so I can remove the whole movement to get to the Cap which I assume is underneath. Other owners on some other watch forums have reported the same experience I had with my Lorus/ Seiko 851 model, the Capacitor fails after only 8 to 10 years and nothing like the "promised" 80 years (Life Time Warranty they refuse to obey). Quite a few owners wrote that they had the Capacitor replaced, but no details on HOW. Read my response above to "watchweasol". There's been some conflict about which capacitor to use as well since the original 2023 24T / MT920 was discontinued 30 years ago (probably the reason all these Lorus Solar watch never met the 80-year promise. Supposedly the replacement Cap is a 3023 24T now. The word in some forums is that this Maxell Cap will last 30 to 40 years. The Seiko Kenetic watches supposedly also use this same Capacitor. Have you ever worked on the Seiko Solar version of this Lorus? Thanks.    
    • @watchweasol - I  know that was the Seiko "company line" for both the Seiko and Lorus branded "Solar Power" versions, but there are an awful lot of folks that bought both and found the Capacitor died, like mine, only after 8 to 10 years and did have the Capacitor replaced with at first the original 2023 24T version and then the 3023 24T, which is apparently a much longer lived replacement. Seiko's "promise" of an 80-year life for this Capacitor was all hooey and likely the reason Seiko quickly dropped both their own branded model and the Lorus ones after just 10 years on the market. Both Seiko and Lorus (who is no longer in North America) refuse to honor the "life time" warranty. One of the reasons I now trust Casio more than Seiko for warranty promises. The movement in the Lorus is literally the exact same one that was in the 3 "Solar Power" Seiko mens models, a Seiko NA tech admitted that to me almost 30 years ago when mine stopped charging. I bought it new in 1986 or 87, and I still have the original paper manual and box and "Life Time Warranty" card (good for nuthin'). I've been a watch and clock "collector" since a teenager, prefer early American pocket watches, but who doesn't love early American MADE and Japanese and Swiss made wristwatches? So I've also collected all the tools a watch and clock tech uses, many pretty vintage too, and learned how to work to a certain degree on most any watch or clock, restoring and fixing, to my limits. I already have that (another version) Bezel removing tool, am just trying to confirm that the bezel is NOT a screw on, or absolutely IS a press-fit. Was hoping to find someone that has either worked on the Lorus version or the sort of same looking Seiko versions that also had the one-piece "tub" body. The Bezel only looks like a rotating time ring, but it's just a "faux" divers watch, only rated to 50m. I think the Seiko version actually had a rotating ring and Tritium on the hands and numbers and was rated to 200m or something. This Lorus/Seiko is an odd-ball and there is absolutely no repair info on them, so that makes me want to fix it more myself.
    • Very, very nice production.  Really outstanding walkthrough!
×
×
  • Create New...