Omega Constellation Wonky Sweep Hand...need Help.

[noirrac1j]

Hello my watch repair colleagues,

I am having a tough time with my Omega Constellation cal. 751 which I overhauled in December 2014. The other day I wore this watch and it was fine all day. I had a meeting to go to that evening, and it was then I noticed that the sweep hand had somehow hung up on the minute hand. I turned the crown to release the sweep second hand, but only succeeded in spinning it around along with the minute hand.  At that point I took the watch off to prevent damage.

 

When I got home I discovered the sweep hand had come off and the watch was running. I then opened the  watch case, removed the movement and reattached the sweep hand and placed the watch in ,y display box.  The watch was running fine when checked a little later, but the next day I was horrified to see that the sweep hand had come completely off again even though the watch was not being worn.

 

 

I again opened the case this evening and removed the bridge to check the sweep second pinion. I looked fine and it was properly seated and engaged with its corresponding drive gear. I placed the sweep hand back on without the bridge and it worked fine---the only little thing was that it was hitting the movement holder so I replaced the bridge and the oscillating weight while holding the movement in my hand. After this I noticed the sweep hand seems to be wonky and spins around if the movement is rotated. If I set the movement on a flat surface, the sweep hand arcs as it should—If the movement is moved in a twisting manner, the sweep hand swings down to the bottom (6 hour marker)..if set down onto my workmat, it begins anew its upward arc towards the 12 hour marker.

 

 

 

 

 

 

 

 

1) What is going on? Do I need a new sweep second pinion (part 1253A), or is the sweep hand itself somehow not properly seated, damaged in some way, and needs to be replaced? I pushed it down onto the pinion hard enough for it to be secure--I am sure of this.

 

2) Is the bridge causing some disturbance the sweep second pinion? I noticed the sweep hand was fine while I had the bridge removed, but once I had in back, on it got wonky.

 

I am baffled and am almost ready to sell this watch for parts….and its one of my favorites! Please give me some input.

 

Thanks.

 

JC

[anilv]

Hi Noirac,

 

When you said you pressed the seconds hand on firmly.. did you support the backside of the pinion?

 

If you did not do this it would not be possible to get the seconds hand on correctly.

 

Also the spring pressing on the back of the seconds hand could be out of adjustment.. it needs to apply some pressure on the back of the pinion.

 

Anil

[Geo]

+1 for Anil's expanation.

You must support the pinion when pressing on the hand.

I use my staking set fitted with and inverted flat punch to support the pinion while gently but firmly pressing on the second hand with a second flat punch. I finish off by fitting the small spring at the bottom that prevents flutter of the sweep second hand. This also allows you to make sure that the spring has the correct tension to do its job.

[noirrac1j]

+1 for Anil's expanation.

You must support the pinion when pressing on the hand.

I use my staking set fitted with and inverted flat punch to support the pinion while gently but firmly pressing on the second hand with a second flat punch. I finish off by fitting the small spring at the bottom that prevents flutter of the sweep second hand. This also allows you to make sure that the spring has the correct tension to do its job.

 

 

Thank you Anil and Geo for your input. I didn't know I needed to support the sweep second pinion while placing the sweep hand.... I willl certainly try this later and re-post with an update. I was hasty when I said I would sell the watch for parts; its just that I get panicky when things like this happen and I don't have an answer. Of course, you guys help assuage my fears by helping me systematically trouble shoot instead! I don't have a stake set, but I do have a good hand (usually), so I'll simply improvise a way to hold the pinion in place while pushing the hand on....I'll also give the spring a slight twist to let it exert a little more pressure to prevent the flutter. Muchas Gracias!

 

JC

[noirrac1j]

Hello,

I was able to press the sweep second hand onto the seconds pinion very firmly and also tightned the spring a bit. The sweep hand moves around the dial as it should, but still flutters if I lift he watch from horizontal to vertical. I also observed the pinion carefully while I lifted and turned the movement around and could see no unusual movement of the seconds pinion and the drive gear--They were still properly interlocked and moving as they should. I don't know if I should attempt a complete tear-down or replace the sweep hand and the sweep second pinion in the hopes that perhaps it is something to do with those two parts. Does anyone know if there could be another reason that a watch can run, keep time, and yet have the sweep second hand flutter and spin around if the watch is tiltled, but runs fine if the watch is laying flat. I'm open to suggestions with this one!

 

JC

[CKelly]

One thing that might be going on is that the hand itself is loose on its tube. That would allow it to slip a bit when not laying flat. It might be worth trying a generic second hand to see what happens.

Charles K

[Geo]

One thing that might be going on is that the hand itself is loose on its tube. That would allow it to slip a bit when not laying flat. It might be worth trying a generic second hand to see what happens.

Charles K

This is well worth checking!

Although the you have checked the operation of the pinion gear and driving wheel, the backlash that causes this problem is so small you may not be able to see it happening. Try holding the watch vertically with 12 at the top and look at the hand again, if the spring is the problem, the flutter will be greatest as the hand is between 2 and 4 on the dial. If it is the tube it will have more of a problem between 8 and 10.

Another thing to try is by gently exerting a little extra pressure on the spring with a piece of pegwood. This should be also done with the watch in the vertical position, and watch the action of the second hand for a complete revolution. If this removes the flutter, give the spring another wee tweek to increase the pressure.

[noirrac1j]

This is well worth checking!

Although the you have checked the operation of the pinion gear and driving wheel, the backlash that causes this problem is so small you may not be able to see it happening. Try holding the watch vertically with 12 at the top and look at the hand again, if the spring is the problem, the flutter will be greatest as the hand is between 2 and 4 on the dial. If it is the tube it will have more of a problem between 8 and 10.

Another thing to try is by gently exerting a little extra pressure on the spring with a piece of pegwood. This should be also done with the watch in the vertical position, and watch the action of the second hand for a complete revolution. If this removes the flutter, give the spring another wee tweek to increase the pressure.

Thanks Geo. This suggestions is a great idea , and I would not have thought that to check where in its rotation the flutter occurs would give a hint as to what might be happening. I've seen your postings, and you and Anil (several others too) are a tremendous resource. I'll check using the suggested technique. More in a bit....

 

JC

[noirrac1j]

Hello and Good morning afternnon and evening,

 

I've checked the location of the flutter by holding the watch vertically (with 12 at top) and the sweep hand can neither complete the upward arc from 6 towards 10, nor can it sustain its arc from 2 moving downward towards 6: it simply slides down to the 6 regardless. I practically took the entire watch apart and checked the sweep second pinion and it was fine (not in the mood for picture taking by this time) and I am going to try a new sweep second hand. I want to beg and plead with the watch, coax it gently, force it to my will, hit it with a hammer, or simply let it languish without hope---I am at a loss.

 

JC

[Geo]

Hi Joe, it sounds like the second hand tube is either too slack on the pinion, or the tube is slack in the hand.

[bobm12]

Maybe the tube -- in the hand -- is cracked (or bell shaped) and can't exert the proper pressure on the pinion, Joe. This will probably surface when you try another hand in its place. Don't despair, remember patience is key! Maybe let it rest for a couple of days and then go back to it with renewed interest.

 

Cheers,

 

Bob

[noirrac1j]

Thank you Geo and Bob. I am going to try a new generic hand and see how that goes......For some reason, a new sweep pinion costs over $40, and so a generic set of hands would be a better solution ($12.00)  at this time. The strange thing is that the watch was working fine--and continues to keep time--up until the moment I noticed the sweep hand hand had become stuck on the minute hand, and later  it came off completely. Perhaps at that moment the tube on the hand was damaged or stretched out. At this point, this is as likely an explanation as any. More to come....

 

JC

[Geo]

Keep us posted Joe, you'll get there. :)

[noirrac1j]

I've been super-super busy with school and also tending three interns this summer, but wanted to give an update on this Omega Constellation 751. Well I twice ordered a generic set of Omega hands from a seller on 'bay (JandKwatches) but they did NOT work. I bought them twice thinking maybe I got a ill-fitting sweep second hand or something, but the second one was the same. These replacement hands do not fit the sweep second pinion because they are slightly too small. I then ordered one from J Borel and again the same thing happened. I tried everything I could think of to make it go on and even held the pinion from behind with all sorts of jerry-rigging to no avail...I stopped for fear of snapping the sweep second pinion and have even more trouble. The watch was running fine and keeping time except for the darn sweep hand which continued to flutter and flop down to the 6 marker whenever beginning its upward swing towards the 12 marker.

 

I then took the old sweep hand, and with my finest pair of  Erem brass tweezers, squeezed as hard as I could over the little opening of the sweep hand. I then pushed it back onto the sweep second pinion again and this time it stood on firmly--there was no fluttering! I replaced the movement in its case and wore the watch over the course of a normal day and everything was fine. No flutter and no falling to the bottom of the dial. This confirmed for me that the problem was indeed that the sweep hand opening had stretched out and was no longer keeping tight tension on its pinion, and this was causing it to slip down on its upward arc as well as the downward arc). Just a word of caution that the "new" hands available for the Omega Constellation 751 do not all fit: my omega is the constellation 168.041 without the integrated bracelet.

 

JandKwatches graciously accepted return of the generic set of Omega hands and of course J Borel did as well.

 

 

Regards,

JC

Edited July 23, 2015 by noirrac1j

[DJT2]

I've been super-super busy with school and also tending three interns this summer, but wanted to give an update on this Omega Constellation 751. Well I twice ordered a generic set of Omega hands from a seller on 'bay (JandKwatches) but they did NOT work. I bought them twice thinking maybe I got a ill-fitting sweep second hand or something, but the second one was the same. These replacement hands do not fit the sweep second pinion because they are slightly too small. I then ordered one from J Borel and again the same thing happened. I tried everything I could think of to make it go on and even held the pinion from behind with all sorts of jerry-rigging to no avail...I stopped for fear of snapping the sweep second pinion and have even more trouble. The watch was running fine and keeping time except for the darn sweep hand which continued to flutter and flop down to the 6 marker whenever beginning its upward swing towards the 12 marker.

I then took the old sweep hand, and with my finest pair of Erem brass tweezers, squeezed as hard as I could over the little opening of the sweep hand. I then pushed it back onto the sweep second pinion again and this time it stood on firmly--there was no fluttering! I replaced the movement in its case and wore the watch over the course of a normal day and everything was fine. No flutter and no falling to the bottom of the dial. This confirmed for me that the problem was indeed that the sweep hand opening had stretched out and was no longer keeping tight tension on its pinion, and this was causing it to slip down on its upward arc as well as the downward arc). Just a word of caution that the "new" hands available for the Omega Constellation 751 do not all fit: my omega is the constellation 168.041 without the integrated bracelet.

JandKwatches graciously accepted return of the generic set of Omega hands and of course J Borel did as well.

Regards,

JC

Congratulations on your repair. For a newbie like myself, it's great to read people's fault finding & problem solving techniques. Post's like this that give real detail & end in a happy conclusion are a fantastic resource. Thanks

Sent from my GT-I9505 using Tapatalk

[CKelly]

Hi,

  I ordered a new Omega second hand from Borel myself and it was just a bit tight as well. After trying as you did I eventually took a small broach and opened it up just a bit and after that everything was fine. Wondering if they are all a bit snug.

[noirrac1j]

Hello CKelly,

Thanks for you comment. I guess if it also happened in similar way with you the new genuine hands frm Borel must all be snug. I don't have a small broach to try what you did, but the original hand went back fine after I squeezed it--come to think of it, I believe I used fine steel tweezers and not my brass. In any case, it worked. Thanks for the input CKelly.

 

Regards,

JC