6497 clone mainspring

[drD]

I have recently started to take apart the clone 6497 from a watch which had stopped winding effectively. I removed the mainspring from the barrel but it was fractured. Ive tried measuring it with verniers but cant seem to find a mainspring for it on cousins. Does anyone have an idea of the spring required, or is it better just to buy a new unitas complete barrel with arbor and spring? third option would be to buy a new clone but this seems bonkers in terms of cost. Any suggestions would be gladly received as im desparate to put it back together and isee if i can make it run...

TIA

drD

[VWatchie]

https://www.cousinsuk.com/search?searchTerm=GR43071

[praezis]

If you post the inner barrel diameter, we can suggest an appropriate strength ans length. For height you can measure the old spring.

Frank

[drD]

thanks guys, i got it at approx 630 long, 1.44  height, 1.0 thick barrel inside 14.4

is the length not that important?

[drD]

3 hours ago, VWatchie said:

https://www.cousinsuk.com/search?searchTerm=GR43071

If that fits would the length longer also work £7 rather than £23??

[Nucejoe]

How long is the £7 one? 

[drD]

480 vs 440, https://www.cousinsuk.com/sku/details/mainsprings-by-list-watch-pocket/gr4309

[praezis]

5 hours ago, drD said:

thanks guys, i got it at approx 630 long, 1.44  height, 1.0 thick barrel inside 14.4

For 14.4 mm barrel a spring 0.17 - 430 ... 470 (thickness / length) will be ok.

5 hours ago, drD said:

is the length not that important?

not that 

Frank

[VWatchie]

Ha, this is very interesting! So, by looking at the measurements and then comparing it to other springs we might find a fully working alternative costing almost 70 % less! Never thought of that! I'd guess the £23.35 simply reflects that there are tons of Unitas 6497/98 movements that people still service.

[praezis]

Yes, price calculation is interesting. 
Just a minute ago I looked for jewels 140-50 on a wholesaler's site: 

140-48 $14
140-50 $28
140-52 $14
140-54 $14
...

[drD]

so have loaded the spring into the barrel. it looked like it could only go one way to latch into the abor - does this look right becasue i cant get it to wind up?? Noob idiot question im sure. 

[nickelsilver]

That's the correct orientation, but the inner coil looks too large for the arbor. Did you buy the longer spring? It's tricky to close the inner coil, ideally you would have pliers with  concave and convex faces opposing which can reduce the radius of the curve. If you try, it's good to heat the tool in an alcohol flame until almost too hot to handle, it doesn't affect the heat treatment of the spring but does facilitate the bending process. Nivaflex is resistant to plastic deformation- it tends to go straight to "breakage".

 

[jdm]

4 hours ago, drD said:

 i cant get it to wind up?? 

Most likely the innermost coil is a bit too large to engage the hook. See if you can close it a bit, pressing gently and not near the hole which has less material. Too much squeezing and it will break, be advised.

Edit - above you have it, master Nickelsiver always ahead, better, and with more tricks. I never want to play cards with him.

[drD]

4 hours ago, nickelsilver said:

That's the correct orientation, but the inner coil looks too large for the arbor. Did you buy the longer spring? It's tricky to close the inner coil, ideally you would have pliers with  concave and convex faces opposing which can reduce the radius of the curve. If you try, it's good to heat the tool in an alcohol flame until almost too hot to handle, it doesn't affect the heat treatment of the spring but does facilitate the bending process. Nivaflex is resistant to plastic deformation- it tends to go straight to "breakage".

 

yes bought the larger spring, i bought 2 incase i broke one so i guess ill have a go at bending it.. Thanks for the advice.

[drD]

are you saying try and bend in this region?

 

 

[JohnR725]

On 3/10/2022 at 12:58 AM, drD said:

clone 6497

Then is it really a 6497? The reason I ask is there's at least two of them, there is the normal one we think of that sometimes is called a 6497-1 this runs at 18,000 beats per hour. Then there is the more common Chinese clone which is known as a 6497-2 this runs at 21,600. The reason for asking is there is quite a bit difference between the two of them a lot a similarity but a lot of differences. In particular one difference is the mainspring both mainsprings are different both arbors are different and both barrels are different. Then somewhat unhelpful answer is from the bestfit website I copied and pasted the information below as you can see both mainsprings are different.  So the reason you might be having some issues is if you're getting the wrong mainspring. 

ETA 6497-2  770/274  771/6497-2 GENUINE MAINSPRING

ETA 6497-1  770/288  770/ETA6497-1 GENUINE ETA MAINSPRING

 

[nickelsilver]

Yes, distributed along the whole curve right up to where the next coil starts.

[jdm]

7 minutes ago, nickelsilver said:

Yes, distributed along the whole curve right up to where the next coil starts.

If one had a tool with a suitable / special collet, do you think that would work? 

[drD]

@JohnR725 thanks for the info, id assumed it was a 6497 and it follows the 6497 unitas cailber on a diagram of parts and assembly. ill have a look at the mainsprings you noted also . Thanks

[JohnR725]

56 minutes ago, drD said:

id assumed it was a 6497 and it follows the 6497 unitas cailber on a diagram of parts and assembly.

Technically they both 6497's They just have a – with another number. For instance if you look at the two PDFs that I have attached other than the cover page they look identical. On the cover page we find out there's a different frequency and the running time of each is different. Otherwise the documents are identical. Then unhelpful is any information related to mainsprings as apparently they very. Even if you go back to the older documentation it's not entirely clear whether they have separate mainsprings are not.

 

ETA CT_6497-2_FDE_482448_13.pdf ETA CT_6497-1_FDE_482160_11.pdf

[drD]

thanks for the above info - they both look the same dont they. as a chinese clone i wonder which ive got. tried bending the mainspring but could get it tighter until i bent it! Then i fractured it. will have another go with the second. then its a toss up between buying another cheap calibre or the more expensive mainspring, my main consern it that that spring may also not lock into the abor. 

[JohnR725]

5 hours ago, drD said:

they both look the same dont they. as a chinese clone i wonder which ive got.

The easiest way to tell would be to put it on the timing machine and see the frequency. But even without that I suspect most if not all the clones at least currently will be 6497-2 movements

5 hours ago, drD said:

Then i fractured it.

 

On 3/13/2022 at 5:24 AM, nickelsilver said:

It's tricky to close the inner coil, ideally you would have pliers with  concave and convex faces opposing which can reduce the radius of the curve. If you try, it's good to heat the tool in an alcohol flame until almost too hot to handle, it doesn't affect the heat treatment of the spring but does facilitate the bending process. Nivaflex is resistant to plastic deformation- it tends to go straight to "breakage".

Interesting about heating up suppliers? My experience has been with any of the modern White Springs if you try to bend it it breaks. The person I work with tried something which does work which is taking a piece of peg would in the center and then you squeeze the peg what keeps you from bending it too much and I've had great success handing it to my boss and having him do it because of I try to bend it it will break. So with the peg with air and you slowly manipulating it you don't put enough of a curvature to break the thing I'll have to try the hot plier method

5 hours ago, drD said:

my main consern it that that spring may also not lock into the abor

Seeing as how you have your barrel apart what you measure the inside diameter of the barrel and the outer diameter of the arbor that goes on the mainspring. I left myself a Post-it note we have 6497 parts that work all measure one of those these I'm curious if there's an actual difference like the parts list or at least some of them indicate. Because my guess is in order to get a longer running time there's more mainspring in their they had to shrink something or make the barrel slightly bigger or maybe they did both. Even though visually they look identical at least on the plans

[drD]

14 minutes ago, JohnR725 said:

piece of peg would in the center and then you squeeze the peg what keeps you from bending it too much

great idea. ill try that with the second spring - would you recommend doing this whilst its still in its packing ring or once its in the barrel? once the spring is free o never seem to be able to free hand coil it back, and the cost of the spring winders is eye watering!

 

16 minutes ago, JohnR725 said:

Seeing as how you have your barrel apart what you measure the inside diameter of the barrel and the outer diameter of the arbor that goes on the mainspring.

ill measure it and give the internal dimensions

[JohnR725]

5 minutes ago, drD said:

would you recommend doing this whilst its still in its packing ring or once its in the barrel? once the spring is free o never seem to be able to free hand coil it back, and the cost of the spring winders is eye watering!

Trying to do it in the barrel would be at least in my experience different costs if not impossible. I can usually do it with the American mainsprings or the older blued steel spring is as their soft in the center. Which gives you the only option of still doing it in the ring which is nice can give access to both sides. Ideally you should have mainspring winders

[JohnR725]

13 hours ago, drD said:

ill measure it and give the internal dimensions

As I have a broken 6497 running at 21,600 I assume that means it's a 6497-2 equivalent. Broken because I found winding it much easier to do than a standard  6497 and then fell off mysteriously. Yes you could see it was welded into spots and they were very security came off. But that didn't give the opportunity to take the work where we have brand-new 6497 parts to compare.

You can see in the photograph the clone is on the left and the standard spring is on the right visually they're just a little bit different in size the arbor for the clone is 3.65 mm in diameter the standard is 4.10.