Tavannes Trench Watch

rleegabe

Registered User
Oct 4, 2001
544
10
18
68
Alderwood Manor Washington State
Country
Region
Having a devil of a time finding a mainspring for this watch. Have called Timesavers, Esslinger, McCaws, Daves watches Cas-ker, Cousins in Great Britain, no luck. It measures in Dennison 7x7x12 1/2 inches long, in millimeters it's Width 1.63x thickness 0.19x length 318mm the watch is a Tavannes 13 ligne movement an old trench watch. Serial number 39959. If anyone knows who else I might try would appreciate a response, thanks.

IMG_0922.JPG IMG_0924.JPG IMG_0925.JPG IMG_0926.JPG front.jpg
 

Chris Radek

NAWCC Member
Apr 13, 2014
817
336
63
Lincoln, NE, USA
timeguy.com
Country
I suspect it's just wrong. Bestfit shows 13''' tavannes taking 6x11x11.5 (cal 330) and 7x10x13.5 (cal 370) springs.

7 seems too strong for a fully jeweled time-only movement. Bestfit does show 7 strength (7x7x16.5) for some 15''' tavannes movements.
 
  • Like
Reactions: rleegabe

Chris Radek

NAWCC Member
Apr 13, 2014
817
336
63
Lincoln, NE, USA
timeguy.com
Country
Hold on a second, it can't really measure 0.19 mm thickness!? That's a 7x4 spring. I don't think your numbers make sense, can you say more about how you measured, and maybe show us a picture of the old spring in the barrel?
 
  • Like
Reactions: rleegabe

rleegabe

Registered User
Oct 4, 2001
544
10
18
68
Alderwood Manor Washington State
Country
Region
Hold on a second, it can't really measure 0.19 mm thickness!? That's a 7x4 spring. I don't think your numbers make sense, can you say more about how you measured, and maybe show us a picture of the old spring in the barrel?
I used my electronic caliper so it may be off, but I used my Dennison gauge and the spring was 7 wide, 7 in strength and 12 1/2 inches long.
 

rleegabe

Registered User
Oct 4, 2001
544
10
18
68
Alderwood Manor Washington State
Country
Region
Having a devil of a time finding a mainspring for this watch. Have called Timesavers, Esslinger, McCaws, Daves watches Cas-ker, Cousins in Great Britain, no luck. It measures in Dennison 7x7x12 1/2 inches long, in millimeters it's Width 1.63x thickness 0.19x length 318mm the watch is a Tavannes 13 ligne movement an old trench watch. Serial number 39959. If anyone knows who else I might try would appreciate a response, thanks.

View attachment 642429 View attachment 642430 View attachment 642431 View attachment 642432 View attachment 642433
Would anyone know the caliber of this movement :???::???::???:
 

rleegabe

Registered User
Oct 4, 2001
544
10
18
68
Alderwood Manor Washington State
Country
Region
I suspect it's just wrong. Bestfit shows 13''' tavannes taking 6x11x11.5 (cal 330) and 7x10x13.5 (cal 370) springs.

7 seems too strong for a fully jeweled time-only movement. Bestfit does show 7 strength (7x7x16.5) for some 15''' tavannes movements.
Saw that to but the spring is only 12 1/2 inches long. I have another movement that is the same so will tear down to compare. Didn't want to because it was serviced before I got it.
 

gmorse

NAWCC Member
Jan 7, 2011
12,337
2,037
113
Breamore, Hampshire, UK
Country
Region
Hi rleegabe,

Go back to first principles; measure the ID of the barrel, the OD of the arbor and the barrel's inside height and plug those figures into the calculators here.

The strength of a spring is proportional to its width and the cube of its thickness, so accurate measurement is essential and a vernier caliper just isn't good enough.

Regards,

Graham
 
  • Like
Reactions: rleegabe

Chris Radek

NAWCC Member
Apr 13, 2014
817
336
63
Lincoln, NE, USA
timeguy.com
Country
It's completely standard to see springs measured in mm or dennison for the width and strength (thickness) and then inches for the length. I don't know why. I could go over to the drawer and show you 100 springs marked this way, and probably none in all mm.

On some old springs, especially Elgins, they would mark the strength in inches too (4 decimal places), but this is rare today.

I am surprised but pleased when I see a listing with all three numbers in mm. Of course that's the way that makes the most sense today, but to me at least, it's not standard yet. Just flipping through the Cas-ker mainspring catalog, springs are listed primarily in dennison/dennison/inch and sometimes also have mm/mm/inch. No lengths are given in mm. So I guess my advice is be ready to interpret any system. Fortunately you can tell them apart pretty easily. Your watch's spring is not .0037 mm thick, and it's certainly not 11mm thick, nor is it 300 inches long.

One way this gets tricky is a lot of times I see mm and cm confused, so something will explicitly say .115 mm, when they mean 1.15mm. The mainspring list in the Shugart book is full of this kind of mess.
 

Chris Radek

NAWCC Member
Apr 13, 2014
817
336
63
Lincoln, NE, USA
timeguy.com
Country
Wow I've lived here all my life and never noticed that americans use weird measurement systems! Doesn't everyone measure their body weight in bald eagles per oil well? No wait, some people use "stone" for that :emoji_stuck_out_tongue_winking_eye:

I probably rambled on, but my point was, it's good to understand the systems commonly in use if you're looking for a mainspring, so I tried to explain them. All of us in this business have to use suppliers all over the world, old books, old stock, etc etc.
 

Al J

Registered User
Jul 21, 2009
673
98
28
Canada
Country
Region
Conversion chart for anyone who might need it. No idea where I got this from, but have had an electronic copy for years now. I use it often as a lot of the books like Bestfit always list springs in Dennison...

Mainspring chart.jpg
 
  • Like
Reactions: rleegabe

gmorse

NAWCC Member
Jan 7, 2011
12,337
2,037
113
Breamore, Hampshire, UK
Country
Region
Hi Al,

There's a typo in the worked example at the bottom of this table:

Screenshot 2021-03-10 141731.jpg
It should read '113.0976 ÷ .2'.

Regards,

Graham
 

gmorse

NAWCC Member
Jan 7, 2011
12,337
2,037
113
Breamore, Hampshire, UK
Country
Region
Hi Al,

You know this isn't "my" document, right? I just use it for the conversion tables...
Yes, I know, I'm just thinking of anyone freshly coming to this subject . . .

Regards,

Graham
 

Forum statistics

Threads
164,923
Messages
1,435,155
Members
85,880
Latest member
Augustiner
Encyclopedia Pages
1,101
Total wiki contributions
2,872
Last edit
Rockford's early high grade movements by Greg Frauenhoff