7750 chrono minute hand question

[Marmac]

Hi folks

So, im working on my old Chronomat. And im just not getting the minute (chrono) hand right. So, it will align fine at 12" (30) when reset. But when i start the chrono and the first minute goes, then it will be sligthly over the 1 minute, and from there its ofcourse missing all minutes after that. Until reset, then its back to center at 12 (30).. Any clues? Maybe its not that visible in the photos, but its pretty obvious that its unalign after start "in real life"

I've also done a Baume Riviera Chrono i have, 7753. On that one the minute hand is also center when reset. But immidatly when i push the start butten, the minute hand will jump/go just a little bit forward, making it unalign for the rest of the "run".. Also that one will return fine to center when reset. (for the most time, 1 of 20 times it will return to ca 5-10 min mark. Then with a start-stop-reset it will return to center again..

 

So, i loved working with these movements, but im just off with that chrone minute hand it seems

[nickelsilver]

When you start the chrono does the hand move a little? On this movement the hammer is in full contact with the heart cams of both seconds and minutes; in that position you should verify that the minute jumper is making full contact with two teeth on the minute counter wheel. If not, loosen the screw for the jumper slightly and adjust the eccentric (it requires a special tool, but there are cheap ones available).

 

If the jumper is making proper contact with the hammer down, then it's an issue with the dial.

[Marmac]

16 minutes ago, nickelsilver said:

When you start the chrono does the hand move a little? On this movement the hammer is in full contact with the heart cams of both seconds and minutes; in that position you should verify that the minute jumper is making full contact with two teeth on the minute counter wheel. If not, loosen the screw for the jumper slightly and adjust the eccentric (it requires a special tool, but there are cheap ones available).

 

If the jumper is making proper contact with the hammer down, then it's an issue with the dial.

Thanks Nicklesilver. Well, not on the Chronomat. But on the Baume, yes it moves just a bit when pushing the startbutton.

[nickelsilver]

16 minutes ago, Marmac said:

Thanks Nicklesilver. Well, not on the Chronomat. But on the Baume, yes it moves just a bit when pushing the startbutton.

In that case see how it does all the way around, if it's a printing issue or the dial isn't centered, it should line up on some then go back out of alignment. I do a lot of chronos and see alignment issues often; I get things dead on at zero as that's the most disconcerting, not much you can do (usually) for off center dials or printing. Sometimes you can coax a dial back on center but getting all the holes aligned on a chrono is tricky- and you really don't want to break the feet!