St1606 Movement Calibrating

[Lawson]

Hi Guys,

 

Just completed my second watch.  It's an old Rotary again (can't argue with the price!), this time with an ST1606 Movement.

I've completed a full strip down and service on the movement, and it came up a treat :).

This one had a much more challenging trainwheel setup than my first one ... but with patience it came back together well.

 

 

When I put it on the ACETimer it looks like it needs some calibration.

 

 

I understand the first number means it's running 9 seconds a day slow, and the second is the balance rotation angle; but I don't really understand the other numbers, and would really appreciate some advise and wisdom .... and perhaps a video on calibration from Mark *hint hint* :P

 

PS. I'm enjoying servicing watches so much, and it seems to come quite naturally to me  ... I just regret that I didn't look into watchmaker sooner!

[bobm12]

Hi Lawson, I would like also some more insight into time graph reading. I believe the angle should be bigger (between 270 and 300? I hope anyone reading this can shed some more light on it), so maybe a couple of the balance coils are either touching or maybe some oil have shorted them? In any case, -9s a day is not bad at all! Good job!

[Lawson]

Thanks for the encouragement Bob :)

 

Yeah, it's flicking between 230-240 degrees ... as you can see in the picture.

 

Also one interesting part of this watch.. Instead of an endstone for the centerwheel, it's just got a removable metal shim collar.

 

 

I removed it and there wasn't any jewel underneath, so I just oiled it with 9010 *shrug* not sure it that was a boo-boo or not.

 

[WillFly]

What do you think the purpose of the cut-outs in the ratchet is? Just curious...

[Geo]

What do you think the purpose of the cut-outs in the ratchet is? Just curious...

My guess is that it is purely aesthetic.

[anilv]

In this case, I would agree that its mainly aesthetic.

 

In other cases it may allow for oiling of pivots which may otherwise be covered, worth checking !

 

Anil

[Marc]

Hi Lawson,

 

you're quite correct about the first numbers; -9 seconds daily rate, and 230 degrees balance amplitude.

 

The third number is the beat error.

In a perfectly adjusted watch the beat error will be zero and the watch will tick evenly (or "in beat", think musically), and with the movement at rest, the balance pivot, the impulse jewel, and the pallet fork pivot will all lay in a straight line. When a movement is out of beat the ticks and tocks will be uneven.

 

Beat error can usually be adjusted in one of two way depending on the movement. On more recent watches the hairspring stud is anchored to a lug that can be rotated around the balance pivot (like a second rate adjustment lever) so that the resting position of the impulse pin can be adjusted to bring it exactly in line with the balance and pallet fork pivots. This can be done without any disassembly and with the watch running.

On older movements the hairspring stud is fixed to the balance cock so the same adjustment has to be effected by rotating the hairspring collet around the balance staff. Not so easy as the balance has to be removed from the cock for each adjustment.

Yours looks to be a fixed stud so unless you are confident with working with balances and hairsprings you may want to leave this alone as 1.3ms (milliseconds) is liveable with.

 

The last number is the lift angle of the movement. This is the angle through which the balance rotates whilst it is receiving impulse (or lift) from the escape wheel (via the pallet fork). That's my understanding anyway. It is not something that can be adjusted but is a design parameter of the movement and the timing machine needs this to be able to calculate the amplitude so you need to tell the machine what it is before you start.

 

It's worth mentioning that these values are spot readings for the movement in that particular position and state of wind. to properly regulate the watch you should evaluate it in several positions and check it fully wound and after 24 hours of running. 230 degrees isn't too bad if you didn't install a new mainspring, although it won't be accurate unless the lift angle is correct.

[bobm12]

Hi Mark, excellent explanation. Would you say an amplitude greater than 275 degrees is what we want in a watch? I'm not too sure about the ideal range for that. Thanks in advance.

[matabog]

A good explanation on the lift angle:

 

 

... if I may..

[Marc]

Ideally yes, and if you can get over 300 degrees then so much the better (and in a relatively recent movement expected). However, with vintage watches, unless you are adjusting everything back to the "as new" specs there can be times when >300 just isn't practical. That being said, properly serviced and lubricated, and with a new mainspring, it is achievable more often than not.

 

Incidentally it is most important where complications are fitted that they are taken into account. If a chrono is running then it will reduce the amplitude, and most significantly, if a day or date complication is engaged then the amplitude will also drop, so keep that in mind when you are testing your watches.

[Lawson]

Thanks for all the feedback on this guys.  I'm learning a lot here, and it's greatly appreciated.

 

One question about lubrication and the amplitude.  At present I only have Moibus 9145 for Pallet Stone oiling.  I remember Mark commenting on a video that if the beat rate is over 28000, then you need to use a different oil.  My question is, if I use what I have in a faster beat rate watch, just how much could this affect the movement?

[bobm12]

Hi Lawson, I believe you meant 9415, which is used for higher bit movements. For lower bit ones use 941. Nevertheless, if the only one you have is 9415 you can also use it in the lower bit movements without any problems or so it is said. Bottom line, you are OK with what you have!