• The Bulletins and Marts are again available online. The network connectivity problem has been fixed. Thank you all very much for your patience.

Watch Help How to replace a missing mainspring..

AceHigh

Registered User
Sep 20, 2021
14
1
3
34
Country
I have a couple different pocket watches with empty barrels. I have not seen a thread on here that might help me figure out what the proper mainspring is without having the original mainspring in hand.
It’s possible that I missed the thread if it exists. Any suggestions on how to figure out what mainspring should be installed if I do not have an original to measure from?

Thank You!
 

gmorse

NAWCC Member
Jan 7, 2011
12,930
2,394
113
Breamore, Hampshire, UK
Country
Region
Hi AceHigh,

If you have the barrel and arbor, you can calculate the correct spring from the dimensions of the barrel; the inside diameter, the inside height and the diameter of the barrel arbor are all relevant, together with the calculators on this website. I suggest you start with the 'Reverse Engineering' calculator about 2/3 of the way down, which will give you a fair idea of the spring dimensions. Then you can go through the spring tables in the materials houses and see what matches the closest. The other consideration is the type of outer termination to fit the barrel in question. Bear in mind that the spring must be able to fit in the barrel with the lid on, and that the strength of springs is proportional to the cube of their thickness.

The other way is to ask the materials dealers whether they have springs to fit the particular models of watches in question. If they're American watches, I should try Dave's Watch Parts for a start.

Regards,

Graham
 
  • Like
Reactions: AceHigh

AceHigh

Registered User
Sep 20, 2021
14
1
3
34
Country
Hi AceHigh,

If you have the barrel and arbor, you can calculate the correct spring from the dimensions of the barrel; the inside diameter, the inside height and the diameter of the barrel
Thank you Graham,
You are a wealth of knowledge! I was thinking this was the route I was going to have to go but it is reassuring to hear you say it. Also the resources you provided will be extremely helpful.

Thank you!
-Nathan
 

Forum statistics

Threads
169,773
Messages
1,481,794
Members
49,157
Latest member
DavidEckman
Encyclopedia Pages
1,060
Total wiki contributions
2,965
Last update
-