AS 175 main spring size

[luiazazrambo]

Hello Watchmakers,

I got this AS 175 movement and it seems that its main spring lost its power, it is set and probably is shorter than it was when left the factory. Somebody created a new hook for it. It looks to be in a funny shape on the pics but this is because I measured its length. So it seems to be 1.47 x 0.11 x ~245 at the moment. I could not find 1.47 on cousins page only 1.45 or 1.5. When I have a close look the spring is in level with the inner rim of the barrel so I assume i shall not go for 1.5? I tried ranfft but could not find this movement there. Only on 17jewels but it does no provide dimensions for the mainspring. Could someone give me a hint here please?

AS 175

Best regards,

Lui

[nickelsilver]

Generale Ressorts says 1.40 x 0.11 x 260, their ref number GR 3696

[luiazazrambo]

Thanks a lot! I forgot to mention that the inner diameter of the barrel is 9 mm. Shall I still go for the 260 version?

Edited March 25, 2021 by luiazazrambo

[luiazazrambo]

Okay, I answered that question based on the following calculation and it is 260.

1. Mainspring should only occupy ½ of the barrel.

2. Square the radius of the inside of the barrel and multiply by Pi (3.1416).

3. Square the radius of the barrel arbor hub and multiply by Pi (3.1416).

4. Subtract the area of the arbor hub from the area of the barrel.

5.Divide the outcome by 2 because the mainspring only occupies ½ of the barrel.

6. Divide this mainspring space by the thickness of the mainspring.

[praezis]

14 hours ago, luiazazrambo said:

I forgot to mention that the inner diameter of the barrel is 9 mm. Shall I still go for the 260 version?

Hi,
"8" is the diameter of the ring, it is no property of the spring itself.  Preferably smaller than barrel diameter for convenient mounting

Frank

[luiazazrambo]

It makes perfect sense. Thank you.