Little bit of help needed please

[djolea]

Hi,

after watching Mark`s video on Unitas 6497 Low Amplitude performance problem Seagull ST36 ST3600 i managed to resurrect my old project UT 6498 by just placing an dial washer from Molnia 3602 beneath balance bridge.
Now i haw an interesting problem, UT 6497, after service, is working just fine except winding. It seams like a crown wheel or winding pinion is missing a teeth but they both look perfect even under the 10x magnification. Is it actually mainspring slipping?

[oldhippy]

Have you oiled the winding works? If so what did you use. Make sure you have used the correct screws around the winding, a protuding screw can cause this.

[djolea]

Only grease i have is Moebius 8200. I am using it for lubricating mainspring, barrel and motion works. There are 5 bridge screws + balance bridge on UT 6497/8 are they the same?

At the beginning of winding action there is almost no slipping but as  i wind the mainspring it becomes more difficult to the point that, most probably, i cannot wind the mainspring completely. 

[oldhippy]

I think you should have a look at the Mainspring, barrel and arbor and see if there is any wear, look at the bottom plate and barrel bridge to see if there is wear. Check the spring is the right size, it sounds as if the spring could become barrel bound normally caused be a bad spring, tired spring or one that is too high. The arbor should be nice and smooth on the shoulders with no marks.  When screwing down the barrel bridge if there is a short screw it is normally closest to the stem.    

[djolea]

First of all tx for your help. I will check all parts individually under higher magnification (5x and 10x) this afternoon.

[djolea]

After few hours with my movement i am pretty convinced that slipping is caused by mainsprings barrel arbor end. I spend some time reshaping it and now is much better but not perfect. Slipping is occurring one time i turn the crown and it can be fully wound. Is this possible?

[Khronos]

10 hours ago, djolea said:

Now i haw an interesting problem, UT 6497, after service, is working just fine except winding. It seams like a crown wheel or winding pinion is missing a teeth but they both look perfect even under the 10x magnification. Is it actually mainspring slipping?

I have the same problem with two ST 3600 (clone) movements.  My two cents worth is this.  I have several Chinese movements (not all ST 3600) that have this problem.  My research has led me to the crown wheel.  I don't know what kind of medal they are using but they are not holding up.  The metal is wearing off oh so slightly on the underside of the wheel and then the stem gear starts jumping a tooth and then eventually the entire crown wheel is crap.  The ones I've looked at, it seems the stem gear is not depthing 100% into the crown gear.  Only like about 25%.  The crown gear also seems to have excessive play.  If I hold down the crown gear it will wind fine.  Yes, the screw holding the crown wheel is tight.  I understand it has to turn freely but in my opinion it's a little too loose.  I've yet to see this problem with a real Unitas movement.  Only with the clones.

I would love to find a supply of crown gears that didn't cost more than a new clone movement.     Anyway, this all smacks of poor quality on the clone side. 

Oh, the dial washer under the cock was a good idea in my opinion.    Well done!

[oldhippy]

If the arbor catches the spring and winds and the spring at the other end is holding in the barrel. Then the problem must be in the winding gears, those on top of the barrel bridge or those in the winding. You normly find fragments of steel around which has worn.

[djolea]

Apparently something is happening between click and rachet wheel. At some instance it's like click slips under rachet wheel therefore missing a teeth. All this is very unusual specially because I changed barrel bridge with all parts on it together with complete barrel assembly. Could it be that something is wrong with mainplate?

[oldhippy]

Are you sure you have the little coller in some watchers that goes here.

 

[djolea]

Crown wheel ring is easy, first you put the ring then lubricate and after that goes crown wheel. 
It must be something really stupid. I managed to reduce slipping significantly and now I am going to case the movement. Maybe winding uncased movement causes slipping.

[MrRoundel]

6 hours ago, oldhippy said:

Are you sure you have the little coller in some watchers that goes here.

 

I learned about the existence of this part after cleaning a Wittnauer automatic and having it appear, like magic, at the bottom of the parts container. I now know where it goes, as I have seen it on a few AS movements over the past couple of months. If you're not aware of it, it's easily missed, as it appears to be part of the bridge. At least it did to me. Good luck.

 

[djolea]

Hi guys, managed to reduce slipping to somewhat acceptable amount. After i case the movement i hope it will reduce it furthermore.
But never mind the movement you guys are most well minded forum i have ever encountered. So, once again, thank you.