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Help sizing mainspring

AP1875

By AP1875
in Watch Repairs Help & Advice

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AP1875 WRT Addict

AP1875

Posted
Posted

I unwound a mainspring from an automatic chinese watch. 

As I was greasing the mainspring the end snapped very easily. 

20191102_213023.thumb.jpg.0df6e95fdfb8d2af5542406a92516077.jpg

 

I need to purchase a new one from Cousins. 

 

The measurements I have are 

1.43 high

1.12 thick

500mm long

20191102_212534.thumb.jpg.545275a693d74e39695e37f1f618f09f.jpg

 

20191102_212625.thumb.jpg.2f6ff8b8ce9c5626d4f8c6b669879cdf.jpg

20191102_212811.thumb.jpg.572a5d3226fcb08b281bc5e41195e6c5.jpg

 

I can't seem to find anything on cousins that's close to these measurements? 

https://www.cousinsuk.com/category/mainsprings-by-list-watch-pocket

 

Is it important to get the exact size? How far can I deviate from my measurements? 

Could I use a valjoux 7750

1.50 x. 115 x 600? 

20191102_213023.thumb.jpg.0df6e95fdfb8d2af5542406a92516077.jpg

AP1875 WRT Addict

AP1875

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Posted
1 minute ago, oldhippy said:

What is the cal number? that is all you need. 

It's a chinese clone, so unfortunately I can't rely on referencing the cal. the sizes won't be right. With the measurements I know exactly what I need. 

Nothing matches up precisely on cousins so I am now wondering how much deviation I can allow for? 

watchweasol Distinguished Member

watchweasol

Posted
Posted

Hi   what is it a clone of.  with chinese clones getting the actual replacement will be difficult better to get a GR spring a close as possible making sure the spring height is the same or less to avoid binding on the barrel cover

rduckwor WRT Addict

rduckwor

Posted
Posted

If you must choose, I would match the spring height and strength (thickness) and go a slight bit shorter rather than longer.  A longer spring may bind in the barrel or worse, not fit at all.

Good luck.


RMD

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