Before I Buy

[Takeitapart]

Hello mainspring experts.  I am beginning to put together a Seiko 4205.  I am ready to replace the mainspring into the barrel.  I want to confirm the proper Bergeon arbor, barrel and hand direction.  I have measured the inside of the barrel and it is 7.0mm.  If I read the Bergeon size chart I should use a 6.5mm or #2 size which would fit inside the barrel  Also I believe this is a right hand wind.   Any input would be appreciated

[Jon]

Most springs are clockwise (right handed), but this is an anti-clockwise spring (left-handed). A Bergeon No. 2 is ideal for this. It has to have the blue dot on the winder and not the red dot, which denotes using for an anti-clockwise spring.

Right-hand (clockwise spring) winder has a red dot and left-handed (anti-clockwise spring) has a blue dot.

The reason I call it a anti-clockwise spring is because the direction of the spring from the central arbor is anti-clockwise, or comes out from the arbor in a left hand way. I think calling the spring left hand and right hand are really confusing, rather than clockwise and ant-clockwise, but that's just me.

I hope this helps

Edited February 1, 2024 by Jon

[Takeitapart]

Thank you very much Jon!  I find the right and left quite confusing.  By any chance do you have a photo of a clockwise/right hand  that I could view.  I do better with pictures..

 

Mark

[Jon]

this is an anti-clockwise winder

 

And here is a lesson slide with a clockwise spring

 

Edited February 1, 2024 by Jon

[Takeitapart]

Great! Thank you!!!

[Waggy]

I struggled also, I have a mental trick to distinguish them, when looking at them in the barrel a right hand thread grows to the right (clockwise) and left handed spring grows to the left (anti-clockwise). Then I try not to think about it too much in case I break my mental trick and have to think of another way of remembering it. It's just like a normal thread you would see on a bolt, if you stood the bolt on its hex end and looked down it would have a right handed thread (well 99% of them anyway).