Jump to content

Mainspring Sizing


Lawren5

Recommended Posts

I need to find a replacement mainspring for a Ball pocket watch which uses the Hamilton 992B movement. The broken mainspring measures 2.82 mm wide, 0.16 mm thick/strength and 23.5 inches long. The closest replacement I can find has all the right specifications except that it is only 20.75 inches long, nearly 3 inches shorter. Would using a short mainspring present any problems?

Link to comment
Share on other sites

I don't think the 534B will work because it has a width of 3.0mm whereas the broken mainspring measured 2.82 mm. The 534-718047 with a 2.80mm width is the one I've been considering and should work if the shorter length is not a problem.

Link to comment
Share on other sites

what was bothering me in the back of my mind is I worked on a ball watch and there were some differences and I just can't remember what they were? then before you remove the mainspring did it seem like there was additional space in the barrel for something wider? It's unlikely that they made a custom mainspring for the watch so it would have to be one of the Hamilton mainsprings. so I'm giving you the complete Hamilton 16 size section so you can see what once was available and what is currently available hopefully.

ham-ms.JPG

ham-mb.JPG

Link to comment
Share on other sites

usually the thicker part of the barrel lid isn't a problem because if you put the arbor in the lid that corresponds to that diameter.

I have an image from the 1946 Hamilton material catalog. Basically were down to they used the mainspring for the Hamilton 992 not Hamilton 992B. You notice in the catalog here when it came to end style both the 534 and the 534B are for motor barrels. 

so looking at eBay searching for 992 mainspring keeps coming up with 992B mainspring but I did find a couple in 992 and at least one of them is a white spring which typically makes it newer. The older blued spring is depending upon who made them can hold up and be very nice condition or they can be set and occasionally they get rusty not always noticed by the seller.  Of course getting the white spring means that while you have a whole bunch of choices a very long time ago typically on the modern spring they've consolidated all those choices down to 1  maybe 2  if you're lucky.

 

Hamilton 1946 catalog mainspring list.JPG

Link to comment
Share on other sites



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • That would be something! Which brings me back to;  
    • you think you're going to sleep tonight you're not, you're going to ponder the question of what makes you think those of the right parts?  
    • Does anyone knows what size case a need for a dial diameter 20.60mm?
    • Sounds like the story with my Rolex. Poor (expensive) job done by an official Rolex dealer with an "in-house" watchmaker, hence I learned watchrepair and did the servicing myself. Same story as I learned with the Omega 861, again poor job by an "in-house" watchmaker by an official Omega dealer. Once your watch goes through that back-door, you have no idea what is going to happening to it 🫣   Quite nice that they sent back the parts which had been replaced !
    • yes that's definitely not right at all. I have a picture one of my friends has a Omega coaxial there was having issues to lose asking me where he should send it. As that's a specialty watch I suggested the service center. When he got it back he sent me a picture so the replace the dial as you can see the hands the mainspring barrel and I think the price was really quite decent considering all the stuff they can replace. So I do know they do change the barrels but the other person I worked at the service center when I would ask questions and unfortunately I can't remember all the answers. I think a lot of the changing a parts is at the discretion of the watchmaker. Plus I don't know enough about the chronographs and whether that would be considered a vintage watch? I take some of the vintage watches may have been sent directly to Switzerland or another service center. Obviously with a watch like the one down below they probably have a infinite supply of parts is its relatively modern vintage stuff becomes more interesting even the watch companies don't have necessarily infinite supply of parts. But no matter what the watch shouldn't disintegrated six months that's definitely an issue.        
×
×
  • Create New...