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Seiko NH36 not running well after reassembly

smb88
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Hi all!

I wanted to try my hand at disassembling and reassembling a movement, I picked up a NH36 to give it a go. Disassembly was fine, and I thought reassembling was going well too until it came time to install the balance.

With the balance installed the watch almost runs, but the balance wheel hardly rotates and just doesn't seem right. I've tried removing and reinstalling the pallet fork (a few times) as well as removing and reinstalling the balance (a few times) but pretty much the same result.

Any ideas for what to check next? I guess I'll probably do another complete disassembly if not.

Cheers!

 
ErichKeane
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That looks like a ton of beat error plus low amplitude. Assuming it worked well before you removed it, I suspect there is either shmoo or damage in the gear train. You'll have to start taking it apart a little at a time and examine whether the jewels and pivots are all clean. I suspect end-shake is fine on them if it worked originally.

Another thing to do is to pull the balance and see whether the pallet fork 'snaps' back and forth correctly. I presume you're getting a really lazy one based on the power transmitting.


ONE thing you can check first though: DID you pull apart the balance jewel settings? Could you ahve reversed one of the cap jewels?
 
redpcar
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ah, reversing the cap jewels. Always happens to me. I'll be damned if I can't tell the right side from the wrong...
 
smb88
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ErichKeane ErichKeane
That looks like a ton of beat error plus low amplitude. Assuming it worked well before you removed it, I suspect there is either shmoo or damage in the gear train. You'll have to start taking it apart a little at a time and examine whether the jewels and pivots are all clean. I suspect end-shake is fine on them if it worked originally.

Another thing to do is to pull the balance and see whether the pallet fork 'snaps' back and forth correctly. I presume you're getting a really lazy one based on the power transmitting.


ONE thing you can check first though: DID you pull apart the balance jewel settings? Could you ahve reversed one of the cap jewels?
Thanks for the info!

Hindsight is a wonderful thing, and unfortunately in my haste to start unscrewing things I didn't really check that it was running well before disassembling 🤦‍♂️ lesson learnt...

Yep, the pallet fork is kind of snapping one way but not always the other when manually manipulating.

I didn't touch the jewel settings this time round.

I'll take it apart again and check for damage/gunk and see if that helps.

I'll keep you posted 😉
 
JimInOz
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With the mainspring let down, remove the balance and pallet fork.
Apply some tension to the mainspring and confirm that the gear train runs freely until it stops. If all is good there should even be a tiny amount of backlash at the end of the run.

Then fit the pallet fork, check it is correctly lubricated and then apply tension to the mainspring and check the interface with the escape by gently flicking the fork with the tip of a very soft artist brush.

Once you're happy with that, try the balance again.

Good luck with it.
 
smb88
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JimInOz JimInOz
With the mainspring let down, remove the balance and pallet fork.
Apply some tension to the mainspring and confirm that the gear train runs freely until it stops. If all is good there should even be a tiny amount of backlash at the end of the run.

Then fit the pallet fork, check it is correctly lubricated and then apply tension to the mainspring and check the interface with the escape by gently flicking the fork with the tip of a very soft artist brush.

Once you're happy with that, try the balance again.

Good luck with it.

Cheers Jim, the gear train certainly seems to be running freely with the pallet fork and balance removed, I can even use a puff of air on the escape wheel to spin everything up and it runs nicely.

With the fork fitted and flicked with a small brush it doesn't seem to "snap" back and forth, I've added a video. It seems ok in one direction perhaps, but not the other, any ideas what that might indicate?

 
smb88
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Jan Dietrich Jan Dietrich
NH36 is also a hard one to start with😄
It wouldn't have been my first choice! 😆

It was part of a kit which my lovely wife got me for Christmas as she knows I'm interested in watches and how things work!
 
smb88
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I don't see anything immediately wrong with the fork or balance, although my opinion is next to worthless!

P1090576~2.webp P1090571.webp
 
JimInOz
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In the pic above, is the balance pivot sitting in the jewel and not just on top of the balance cock?
 
Canuck
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Did you oil the jewelled bearings on the pallet arbor. If you did, that is a no no!
 
JimInOz
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Canuck Canuck
Did you oil the jewelled bearings on the pallet arbor. If you did, that is a no no!
Ah yes. I forgot to mention that. Although some Seiko tech guides indicate oiling them I never do.
 
Canuck
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On occasion, I find the holes in the pallet jewels are rather looser than I think they should be, on the pallet arbor pivots. When I run into that, I often find the lever “flutters” as you manipulate it. When I run into that fluttering problem, I put a microscopic dot on the pallet arbor bearings to act as a damper, to reduce the fluttering problem. The danger is in applying too much oil to the top pallet pivot so it migrates between the top of the pallet, and the underside of the pallet bridge. This can result in the action described as the pallet is manipulated.
 
smb88
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Canuck Canuck
Did you oil the jewelled bearings on the pallet arbor. If you did, that is a no no!
No oiling was performed! It was "factory fresh" so I just wanted to take apart and put back together.
 
smb88
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An update!

I had a spare 7S26 movement and I wondered if perhaps the pallet fork and/or balance were compatible.

I swapped over the balance and I think we've found the culprit.

I guess I must have somehow messed it up...

Screenshot_20260110-114600~2.webp
 
smb88
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Thanks for all the help and advice on this is, even though I obviously mishandled the balance somehow I still very much enjoyed the process and learnt a lot!
 
ErichKeane
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smb88 smb88
Thanks for all the help and advice on this is, even though I obviously mishandled the balance somehow I still very much enjoyed the process and learnt a lot!
I was beginning to suspect hair spring after I saw it laying down in that previous one (like Jim asked about!). You should try to place the pivot in the cock and look at the spring in the microscope. I got a feeling you've either bent it up, or, more likely, got itdoing an extra trip around the regulator screw or something.

IF so, you can likely gently just move the bridge and balance around to untangle it a little without getting into too bad shape.
 
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