Damaged mainspring

[dreadnought]

Hello All

Newbie here

I am at present doing Marks watch repair course on level 2,.  I have stripped down the 6497 that he advised working on, all going great till replacing the mainspring into barrel, I have the Bergeon mainspring winders, wound the spring into the winder, turned the arbour back a few turns to take arbour out and out came the mainspring as well all twisted and bent in 2 places, I unravelled it laid it on my bench and it is also not laying flat.  So new mainspring required,  does anyone know which mainspring I should get from Cousinsuk, I measured the length and it is 540mm long the rest I dont know, looks like I will have to buy a micrometer

[watchweasol]

Hi  you will be able to measure the spring Length , thickness, height etc with a vernier gauge,    If its a clone movement (6497) you may have to get the nearest fit as chinese clone spare are hard to find. 

[JohnR725]

9 hours ago, watchweasol said:

clone movement (6497) you may have to get the nearest fit as chinese clone spare

I'm not sure in the cloned mainspring is whether they are different then the original mainspring. But we also have to look at whether it is actually a 6497 or 6497 – something in other words they run at a higher frequency and I think that's a different mainspring than the standard 6497.

10 hours ago, dreadnought said:

spring into the winder, turned the arbour back a few turns to take arbour out and out came the mainspring as well all twisted and bent in 2 places, I unravelled it laid it on my bench and it is also not laying flat.

I think you need to work on your technique here? Usually for the handle when you wind the spring in you let the spring unwind the handle so than there is no tension and then to unhook it you just have to be really careful of what you're doing. So in other words when your winding it backwards to get it done clock you don't want to somehow wind the spring backwards. Because you just trying to get the hook unhook from the spring. The other thing that happens is if you choose a Winder that's too small the entire spring gets jammed inside the Winder and that's an issue.

Fortunately if you choose carefully with the new spring you should build just shove it in and not have to play with the Winder except of course you don't get the lesson of learning how to use the Winder.

Looking at the references the 6497 or 6497 – 1 depending upon the source is either 440 mm or 450 mm. I'm noticing what one of the problems this trying to find a reference for 6497-2 that's what the Chinese clones usually are 21,600bph trying to find a listing of the size of the spring or even finding anyone that acknowledges such a movement exists is proving to be interesting.

Unhelpful because and not getting a size but if you have access to someone would best fit parts its number is 770/274.The other way I see the part number is 771/6497-2 Which is still unhelpful because I can't get a size so I have no idea how big or small it is. Based on run times the Chinese clone watch I suspect that that's probably what you have.

On the other hand if you just Google that you want to mainspring for this listings will come up like this one and it does present a minor problem of pulling the spring is shorter than what your spring is. Which tells us the Chinese modified that and basically it may be an issue.

https://www.startimesupply.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=1&Product_Code=ETA6497-2-MS&Category_Code=1H-Parts-Movt-Mspring-ETA

 

 

[dreadnought]

Hello Everyone

Thankyou very much for a very quick reply, very helpful.

This may be a long reply, but I hope it will be helpful to other newbies like me. 

I set my Daughter on this quest as well she has a lot of years working on the internet, She found one web site with a link to Generale Ressorts mainspring catalogue and downloaded it for me. I am doing Marks Watch repair course, I looked at his website for the Mainspring video as He shows how to use the catalogue, found the Unitas 6497 line, typed the number into Cousinsuk mainspring page and it came up with a mainspring GR4307-1 at £23, but looking just above and below there was 2 more springs exactly the same size and the same barrel diameter, but the cheaper 1 was 40mm longer 1 at £14.75 and 1 at £7.30, any way mainspring ordered.  Be here tomorrow

GeneraleRessorts.pdf

[jdm]

20 hours ago, dreadnought said:

She found one web site with a link to Generale Ressorts mainspring catalogue and downloaded it for me.  

The wondeful thing about this catalogue is that was last updated in 1974. One wonders, what had happened in the following 48 years (beside the  big quartz crisis) No new calibers were made? I very much doubts so.

Anyway, for the casual reader, I recommend consult instead the one which is hosted by Cousins UK. It has many corrections and notes added by a knowledgeable unknown someone. 

[JohnR725]

15 hours ago, jdm said:

The wondeful thing about this catalogue is that was last updated in 1974. One wonders, what had happened in the following 48 years (beside the  big quartz crisis) No new calibers were made? I very much doubts so.

The first edition was printed in 1964 and had 7500 calibers. The second edition as you pointed out was 1974 and now has 16,500 calibers. I wonder if the number of calibers increase in a linear rate probably not plus all of the calibers that were discontinued but are still listed in the catalog

So we do have the problem of new calibers an the specifications not necessarily document the references are old.