6497 Incabloc spring

[oddbod]

Hi chaps, I decided to service one of my Asian 6497 Pam's today, and have hit a snag. It was all going well until I got to the last part of the service, the top incabloc spring on the hairspring staff/ regulator. I opened it up and hinged it upwards and the little blighter dropped out of its seating groove, tried and tried to get it back into its groove, no chance..finally picked the lyre spring up with tweezers (after about 2 hours of hair pulling) and decided a bit more oomph might get it to re-seat. Nope it snapped in half!
I can get genuine ETA 6497 incabloc springs from Cousins for a few quid, the question is do they fit the asian 6497 movements..and also should i get some jewels for the incabloc (just in case) as they're tiny little things which tend to ping into hyperspace as per the springs??
Does anyone know if the genuine springs and jewel caps fit the asian 6497/

Any help appreciated!!

 

[Mike Advice PI]

Did you get anywhere with this? I've been in the same situation with a broken spring and couldn't find any clear answer about what might replace it.

I did a bit of research and found that the replacement spring for an Incabloc setting in a Unitas 6497/8 was part number 470.13. I ordered some from Cousins and found them to be too small compared to the broken spring, specifically in the length of the hinge tongue. This photo shows the broken spring beside the replacement.



I then found a photo on the Ofrei site which showed a more promising looking spring with a longer tongue.



That was part number 176.03. I ordered some of those from Cousins, but once again they were too small. This photo shows the broken spring beside the replacement.



I haven't tried to fit the 176.03, but it doesn't look like it will work. Eventually I found some measurements for Inca springs on Boley.de which suggest that the 176.03 is the biggest lyre spring they make. To me that looked like the end of the search.

I suppose the only ways to fix the problem are: (a) buy a new movement and use the spring or the whole balance, (b) find a friendly PAM modder who might have one or two Chinese springs lying around, or (c) buy and have a go at fitting a complete block (go to cousinsuk and search ‘UT64973024’ - info picked up in passing in the PAM forum), which will need tools, skills and experience most of us don't have. It may need a complete Inca block on the bottom as well, and even a Swiss balance to do the job right, according to the modder whose name I forget. Edit: it was Strodda, and his contribution appears in this forum.

In the end I bought a new movement for £35 shipped and switched the bridges and stem over. Now I have a source of spares and a watch that works again, so I'm happy.

If anyone has any other info on sourcing a replacement spring, I'd be happy to hear it.

 

[Tickleshoes]

The Asian "Incabloc" are not based on any Swiss counterparts so swapping gen pieces won't work. The most cost effective option is installing an entire gen setup. I'm going through that now with my 127 - gen incabloc top and bottom.

 

[Mike Advice PI]

As a follow up to this, I put one of the Incabloc 176.03 springs on the upper balance cap jewel and assembled a watch using the movement. After a week and a half's wear it seems to be doing its job just fine.

I thought the spring might shift in use, but it's even survived a fall without moving. I've set it as centrally as possible on the jewel and although the springs don't fit a long way under their retaining slot, they're staying put.

If you were being paid to fix somebody's watch you probably wouldn't risk it, but for a watch tinkerer it's a way to get out of a broken spring problem.