Seiko 7S26C assembly woes

[Jon]

I wrote a set of lessons for the 7S26C some time ago, so you might find these slides helpful. Unfortunately slide 4 regarding the barrel is a video which can't play on this forum, so I copied it as a static slide, so apologies for that.

 

 

 

 

[RobBrandywine]

Whew, I finally got it!  Three things worked for me. 1) Leaving the click spring off.  Many times the barrel would stop spinning and I was able to free it by moving it in the opposite direction. 2) I put the bridge on with only the barrel and 2nd wheel in.  Then added the 3rd wheel, and finally the 4th.  Still having a problem though, so I pressed on the bridge up by the S in Seiko.  This was the final thing, but even then the train would hang even after I had the screws in partway.  I had to back one or the other out a little, always going back to the good known point, and try tightening one of the other screws just a little, until they were all, all the way in.

[JackH]

On 2/8/2024 at 6:39 AM, Jon said:

I wrote a set of lessons for the 7S26C some time ago, so you might find these slides helpful. Unfortunately slide 4 regarding the barrel is a video which can't play on this forum, so I copied it as a static slide, so apologies for that.

 

 

 

 

Excellent information Jon! -- I wish I had this when I started working on the 7S26. 

[RobBrandywine]

Stuck again.  I've got the pallet fork back in and the pallet fork cock.  But when I push the pallet fork back and forth it isn't snapping in place as the videos show.  I can see the left jewel retracting from the escape wheel (directions from the pallet cock facing the escape wheel) but I can'r see the other jewel and so don't know how it is interacting with the tooth over there.  Does the pallet fork have to be set down in a certain orientation to the escape wheel teeth?  Or any other ideas?

[JackH]

Make sure that both pallet pivots are seen through the jewel (top and bottom). The watch needs to be wound a bit to get the pallet to snap back and forth. I usually wind the crown wheel with a screwdriver a turn or two.  

Edited February 19, 2024 by JackH

[nevenbekriev]

4 hours ago, RobBrandywine said:

Stuck again.  I've got the pallet fork back in and the pallet fork cock.  But when I push the pallet fork back and forth it isn't snapping in place as the videos show.  I can see the left jewel retracting from the escape wheel (directions from the pallet cock facing the escape wheel) but I can'r see the other jewel and so don't know how it is interacting with the tooth over there.  Does the pallet fork have to be set down in a certain orientation to the escape wheel teeth?  Or any other ideas?

The first thing to check is wether You have placed the pivots of the fork in the stones. If so, there will be certain axial free play and the fork will move with no resistance from the bearinfs. If it is OK, then You shoud look at the pallet stones and how they interact with the wheel teeth. Yes, they both are seen. If the 4th wheel doesn't let you see free the entrance pallet, then use the hole in the plate from the other side. And as I expect that You will not understand what You see, make pictures and show them here. In both end positions of the fork.

[RobBrandywine]

Thanks.  I think the pivots are seated correctly.  I watched My Retro Watches place his and I tried very hard to emulate and felt I had.  But when I try to get close enough with enough magnification to see, I block the light.  The fork seems to move freely.  I do see both stones. I've taken 6 photos but I don't know if they are good enough.  It's what I could do with an iPhone.

 

 

Oh, and yes, I did have power in the gear train when I was testing.

[RichardHarris123]

I have just reread the post, you didn't answer whether or not the wheel train was free before installing the pallet.  Is the wheel train free running?  

If not then the pallet cannot snap back and forth because it's not receiving power. 

[Neverenoughwatches]

8 minutes ago, RichardHarris123 said:

I have just reread the post, you didn't answer whether or not the wheel train was free before installing the pallet.  Is the wheel train free running?  

If not then the pallet cannot snap back and forth because it's not receiving power. 

eyup me old mucker

[RobBrandywine]

It was free before I put the pallet fork in.  It isn't free now. 

One thing I noticed that doesn't seem correct is that the exit pallet stone seems to be on the wrong side of the escape wheel tooth.  When I swing the fork arm toward the left, the stone comes up behind the tooth after it has passed whereas the animation I'm looking at shows the exit stone blocking the forward moving tooth.

[RichardHarris123]

Remove the pallet and check for free movement on the wheel train.  I still think that the escape wheel isn't moving freely. 

Edited February 19, 2024 by RichardHarris123

[eccentric59]

1 hour ago, RobBrandywine said:

When I swing the fork arm toward the left, the stone comes up behind the tooth after it has passed whereas the animation I'm looking at shows the exit stone blocking the forward moving tooth.

From the top down (as shown in the pictures) does the escape wheel rotate counterclockwise? I'm wondering if you got the mainspring in upside down. Granted, if that's what's going on  the spring won't engage the hook on the arbor, but you could get a little energy in the wrong direction.

[nevenbekriev]

The entrance pallet seems to be moved much out from the slot. Take the lever out and make some pictures of it, specially the entrance pallet. I don't have Iphone and experience with their camera usage, but Samsung A52 has abilities to make 1000 times beter pictures.

[RobBrandywine]

2 hours ago, RichardHarris123 said:

Remove the pallet and check for free movement on the wheel train.  I still think that the escape wheel isn't moving freely. 

I'm ahead of you there, I did that yesterday.  As soon as I removed the pallet cock and pallet fork, the train was free and the escape wheel spun like a son-of-a-gun.  Then I reinstalled and the train was locked up.  I guess the next step will be to leave the fork in and the cock off and try.  And if it spins then, try installing the cock without screwing down, and test again.

2 hours ago, eccentric59 said:

From the top down (as shown in the pictures) does the escape wheel rotate counterclockwise? I'm wondering if you got the mainspring in upside down. Granted, if that's what's going on  the spring won't engage the hook on the arbor, but you could get a little energy in the wrong direction.

That's an idea.  I could recheck that.  This was a barrel complete so I guess you mean the barrel upside down?  I remember seeing the bowed sides of the arbor and turning the rachet on the arbor until it dropped a little further and locked in place,

Okay, in taking the cock off, I loosened both screws and the escape wheel spun, for about 3 seconds from the energy I had put in.  I'll experiment with a couple of things to see if I can get it spinning as I completely lower the cock.

[RichardHarris123]

If you mean you loosened the screws on the pallet bridge and the escape wheel spun, the the pallet is binding.  Lack of end shake, not properly between the jewels? 

[RobBrandywine]

The escape wheel is turning clockwise.  Is that correct?  Do all brands and movements turn clockwise?  

The big end of the arbor has the rachet screw hole in it, right?  The other end is just a pivot.

The pallet fork.

 

[eccentric59]

Clockwise is correct. It was just a thought, but sometimes exploring less than likely scenarios leads you to the actual problem.

 

[nevenbekriev]

Well, the quality of the pictures is bad, but still I see what I see. I will try to explain, I am not sure to whum - the topic starter or the others in the group...

Look at this picture:

The upper circle shows that the fork is in banking position, it can't move further to the right.

The other circle shows that the tooth of the 'scape wheel can't still leave the impulse plane of the palllet, thow the lever movement in this direction is already limited by the banking.

The normal thought here is:

9 hours ago, nevenbekriev said:

The entrance pallet seems to be moved much out from the slot...

OK, but the last pictures don't seem to show such thing. What I see there is different, but it leads to the same effect:

 

The fork (the tail of the lever) is bent to the direction, shown with green arrow. At least this is what I see and this is the thing that explains what happens. I don't want to speculate how it could happen and why.

 

Edited February 20, 2024 by nevenbekriev

[Nucejoe]

What  cleaning solution  to use, for plastic  mainplate of 7s26.

Link to discussion on proper solution be useful .

 

Edited February 20, 2024 by Nucejoe

[RobBrandywine]

Thank you very much!  I'm going to order a new pallet fork and see if that makes a difference.  It will probably take 2 weeks to get here, though.

Nucejoe - please create your own thread to ask that question.

[Nucejoe]

1 hour ago, RobBrandywine said:

Nucejoe - please create your own thread to ask that question.

PM sent.

[RobBrandywine]

Okay, the new pallet fork came in yesterday and I installed it today and it seems to be correct now.  The exit stone is on the proper side of the escape wheel tooth and the lever arm seems to click when you give it a little push.  On to the next problem, LOL.

[RobBrandywine]

I'm been putting this off because I'm stuck again.  I got the balance positioned and it will rotate when I use my blower on it, but it won't keep in motion.  What can cause this?  Also, it may be unrelated, but it is harder to turn the rachet screw than I remember it being before disassembly. 

[Nucejoe]

1 hour ago, RobBrandywine said:

 I got the balance positioned and it will rotate when I use my blower on it, but it won't keep in motion.  What can cause this?  

Common causes are,

1- Zero end shake on balance arbour. A test for thjs issue is to loosen the cock screw a turn or so.

2-Broken hole jewel or damaged end stone.

3- Hairspring rubbing on balance spokes or on under side of balance cock. 

4- Balance rim rubbing on the fork cock. 

5- Bent staff pivot. must be examined under high magnification.

6- Fork not free to snap back and forth. Check end shake on fork arbour.

7- Tiny hair stuck in the hairspring coil.

8- Roller table rubbing of fork horn.

9- Guard pin rubbing on the Roller table.

Good luck

Edited March 1, 2024 by Nucejoe

[RobBrandywine]

Good stuff, lots of leads.  The only one I can eliminate is #1 because I put the cock screw in a quarter turn at a time, always checking for free movement of the balance wheel.  So, in effect, I've already done that test.