Difficulty identifying balance staff sizing - AS1287

[Pauldoubleyou]

He'll everyone. I have had an AS1287 inside a 50s-60s Iram military style watch for too long, and have had continued issues with it relating to the balance staff. 

 

There appears to be two versions, an earlier non shock balance and a later Inca setup. No matter what I try I always seem to end up with the shorter Inca staffs or balance complete. I've tried four so far and I am getting frustrated. 

Does anyone know of any documentation that would show me the correct staff measurements for a non shock AS1287?

I have found what I think is the right staff (pictured) and have included the ones I currently have (the packet on the watchmakers mat), however I don't understand the measurement method on the packets. Can someone please confirm which of the two is the longer (higher)?

 

Any help much appreciated, especially relating to the measurement standard. thankyou.

[HSL]

If you want some measurements on a non inca there is the one which says sold out BS5484, which is slightly longer than the inca version, guess the BS0414 might be some equivalent but not sure since the rest of the measurements are missing from the BS5484.
Notice there also exists atleast a third version for the supershock. ( And probably some more). So, measure your balance carefully.

https://www.balancestaffs.com/a-schild.php?caliber=1287

[Pauldoubleyou]

1 hour ago, HSL said:

If you want some measurements on a non inca there is the one which says sold out BS5484, which is slightly longer than the inca version, guess the BS0414 might be some equivalent but not sure since the rest of the measurements are missing from the BS5484.
Notice there also exists atleast a third version for the supershock. ( And probably some more). So, measure your balance carefully.

https://www.balancestaffs.com/a-schild.php?caliber=1287

Thanks for your reply. I unfortunately don't have an original staff to measure, as I bought the movement without a balance. Therein lies my frustration. The site you linked to is very helpful though, hopefully I can measure my existing (recently bought) staffs and take it from there.

Edited June 22, 2021 by Pauldoubleyou

[JohnR725]

2 hours ago, Pauldoubleyou said:

There appears to be two versions, an earlier non shock balance and a later Inca setup. No matter what I try I always seem to end up with the shorter Inca staffs or balance complete. I've tried four so far and I am getting frustrated. 

Does anyone know of any documentation that would show me the correct staff measurements for a non shock AS1287?

I think what the problem here is you're asking the wrong question. The question is what part number do I need so that I can end up with the correct balance? Or the correct balance staff for that matter? If you look at the second link it lists the parts for your watch. This is always where things get interesting? you'll notice for balance staff they list seven different ones. For balance complete they do show three but if you look at the part numbers there's only two.

then I attached some images from bestfit online and of course additional problems perhaps. Notice you have lots of choices and probably only one that's right.

then the physical bestfit book becomes interesting because is an indication that there are variations which is of course why there so many listed in the images. but fortunately it looks like you want the basic simple one which should be 100/66.  unfortunately for the third link it's out of stock. then providing this is the right staff number I snipped out a couple of more images of the bestfit book which is what the dimensions mean and the dimensions. One of the irritating things of the physical book is on the dimension chart if you're trying to find a particular staff you just have to be lucky to go through the list and find it it be really nice if they list of the sizes by the numeric staff also.

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&AS_1287

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=AS_1287

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=U\ZD]J

http://www.julesborel.com/s.nl/it.A/id.151223/.f

 

[clockboy]

I have found using as much data from the old balance is most useful. Even when purchasing the correct balance some tweaking is often required 

[praezis]

Hi,

16 hours ago, Pauldoubleyou said:

Does anyone know of any documentation that would show me the correct staff measurements for a non shock AS1287?

Any staff manufacturer's catalog (Ronda, DCN) shows the sizes. You already got them above (L=290).
Ronda's is available as pdf on the Cousins website.

16 hours ago, Pauldoubleyou said:

I have found what I think is the right staff (pictured) and have included the ones I currently have (the packet on the watchmakers mat), however I don't understand the measurement method on the packets. Can someone please confirm which of the two is the longer (higher)?

The staffs in your 1st picture are totally wrong. "1287" is Ronda's staff number - not the calibre, which you find below: "IMER 485". Its length is 308.

There are no staff sizes on the packages.

BTW. the length difference of AS1287 staffs is minimal: ordinary 290, Incabloc 287 (all are 1/100 mm).

Frank

Edited June 23, 2021 by praezis