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Felsa 690 mainspring

avion

By avion
in Watch Repairs Help & Advice

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avion Member

avion

Posted
Posted

Hi

If you're familiar with the Bidynator movement, I would appreciate your help!

The break spring on my Bidynator looks different than the one in this post:

http://forums.watchuseek.com/f6/felsa-690-auto-mainspring-1021404.html

Mine doesn't have the additional "tongue" (this extra piece of layer) see photo please:

There is a tiny notch where the tongue appears in the other post. So maybe it was there once.

What do you think? Is it missing? Could It work without it ?!?!?

Thanks !

Ron

IMG_20160802_184700_HDR.jpg

JohnR725 Distinguished Member

JohnR725

Posted
Posted

So your photo really isn't doing anything for me as it doesn't look like a mainspring? So looking up the watch you have it's an automatic. The link you had talked about it originally was a two-part mainspring. Today they come as one piece which should work fine, I have several listed below.

MSS-WA40 1.45 x 0.11 x 312
Generale Ressorts  3984-X  1.45  0.11  340  
Zf1044, 1.40 x 10.5 x 0.11 x 350mm

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&Felsa_690

 

 
 
avion Member

avion

Posted
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Posted

Yes. It consists of a breakspring and a mainspring. Problem is that the inner barrel of that movement is smooth. So I find it hard to believe that it would work with a "one piece" spring. Are you certain?

JohnR725 Distinguished Member

JohnR725

Posted
Posted

Your mainspring barrel wall is supposed to be smooth. So automatic watches require a mainspring that slips it cannot be permanently attached to the mainspring barrel otherwise the automatic will wind up to the end bad things will happen. So to solve that problem the mainspring has to slip. Thoroughly watches the slipping part was a separate spring with a hook that a standard spring would hook to. Then later on they made it all one spring with various ends that slip. So as long as it's a mainspring of the right size for an automatic it should work. Then make sure you use the right type of breaking grease for the barrel.

ms-1.JPG

ms-2.JPG

jdm Distinguished Member

jdm

Posted
Posted

I consider this kind of interesting. The bridle must slip at the end of winding, but one should to use braking grease to let it grab at all other time, apparently the two things are contradictory.

Maybe Nomos did the right thing on their latest auto movement, no slipping. The rotor stops when the spring is fully wound.  

JohnR725 Distinguished Member

JohnR725

Posted
Posted

Breaking grease interesting substance. So it needs to hold the end of the mainspring until sufficient forces developed to allow it to slip or bad things will happen in timekeeping but it can't slip prematurely as that's equally bad. Then when it does slip it has to be a very high pressure lubricant so you don't grind the barrel itself.

So I have a link to various types of breaking greases unfortunately it does not talk about applying them as the quantities may be different and how they are applied and how to test that the breaking greases actually working.

Then the video shows what happens if things don't work right. Then when he's examining the barrel wall notice it's not smooth? Like everything else in watchmaking there is lots of different ideas not all mainspring barrels have smooth walls.

https://www.youtube.com/watch?v=7KNTrHVD088

http://hiro.alliancehorlogere.com/en/Moebius_8201.html

 

 

 

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JohnR725 Distinguished Member

JohnR725

Posted
Posted
On 8/6/2016 at 2:24 PM, jdm said:

I consider this kind of interesting. The bridle must slip at the end of winding, but one should to use braking grease to let it grab at all other time, apparently the two things are contradictory.

Maybe Nomos did the right thing on their latest auto movement, no slipping. The rotor stops when the spring is fully wound.  

Nomos I be curious to see an image of how they stop the rotor. It's not entirely a new idea automatic watches have lots of innovative things. For instance LeCoultre 497 Also stops the rotor when it's fully wound. Has an up down indicator so you know if it's wound up as there is no manual way to wind the watch.

jdm Distinguished Member

jdm

Posted
Posted
23 minutes ago, JohnR725 said:

Nomos I be curious to see an image of how they stop the rotor. It's not entirely a new idea automatic watches have lots of innovative things. For instance LeCoultre 497 Also stops the rotor when it's fully wound. Has an up down indicator so you know if it's wound up as there is no manual way to wind the watch.

Maybe (I don't know for sure) they simply count on the fact that the very small torque of the rotor, which is only active for fractions of seconds, can't break the mainspring or any other winding component, which according to them are build with special materials http://www.nomos-glashuette.com/the-movements/automatic/duw-3001/ 

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