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Issues replacing complete balance assy on Seiko 4R36A


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Hello everyone - I messed up the hairspring on a Seiko 4R36A when my tweezers slipped while moving the adjustment stud.  As the NH36A is identical to the 4R36A, readily available, and fairly inexpensive, I purchased a complete NH36A and transplanted its complete balance assembly.  I had both movements sitting next to each other, removed the balance plate screw, gently lifted the balance wheel from the plate, and very slowly moved the entire assembly with the balance wheel hanging freely to the other movement.

When it didn't start on its own after installation, I got really worried.  I had to re-fit it two more times until it finally started, but I suspect the new spring might be deformed slightly as the beat angle is low and I had to move the regulator (beat error) stud closer to the plate to keep it running.  Sigh.

I ordered another NH36A to try its balance assembly on the next attempt.  Some questions:

  • The hairspring for these models is crazy delicate - any tips/pointers how best to remove it?  Should I try to support it with another set of tweezers while moving it to the other movement?
  • Should I set the pallet fork to a specific position before the new balance wheel?
  • While watching Mark Lovick's Seiko and NH36A videos, he mounts the balance wheel and then rotates the balance bracket slightly counterclockwise to attach to the stud.  He seems to let the balance wheel hang freely.  Is that the preferred way of installing it?
  • Seiko/SII call out the "mirror finish" on the balance wheel/plate in the service manual.  Should I be using tweezers with rubberized grips?

Many thanks in advance.

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Two additional questions:

  • When securing the balance plate, should I apply gentle pressure to the far end to "snap" it to the stud and then tighten the screw, or should I tighten the screw first?
  • Should the balance wheel start on its own before I tighten the plate screw?
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4 minutes ago, OrbitalGolem said:

I purchased a complete NH36A and transplanted its complete balance assembly.  I had both movements sitting next to each other, removed the balance plate screw, gently lifted the balance wheel from the plate, and very slowly moved the entire assembly with the balance wheel hanging freely to the other movement.

You replaced the balance cock, together with the balance of course. "balance complete" consists of the balance wheel (and staff) with the hairspring. There are two ways to that, one is with the balance dangling, another is using a (preferably wide tips) tweezers to gram wheel and cock as one part. This 2nd method is preferable only if the balance jewels have been removed already, otherwise with the balance pivots sitting at a forced angle in the hole jewels, there is a chance to bend them.

4 minutes ago, OrbitalGolem said:

When it didn't start on its own after installation, I got really worried.  I had to re-fit it two more times until it finally started, but I suspect the new spring might be deformed slightly as the beat angle is low and I had to move the regulator (beat error) stud closer to the plate to keep it running.

You should document your questions with pictures. Place the balance cock flat and the balance in the hole, short straight up with the best lighting and camera (phone) settings you can get.

4 minutes ago, OrbitalGolem said:

I ordered another NH36A to try its balance assembly on the next attempt.

I recommend that you practice on something cheaper than that, because at $40 a pop it becomes an expensive exercise quickly.

4 minutes ago, OrbitalGolem said:

 

  • The hairspring for these models is crazy delicate - any tips/pointers how best to remove it?  Should I try to support it with another set of tweezers while moving it to the other movement?

See answer above.

4 minutes ago, OrbitalGolem said:
  • Should I set the pallet fork to a specific position before the new balance wheel?

Too early for you to try that way. Just set the balance into the lower hole first. Then the upper hole, with the cock not fully set into it's posts yet. If the impulse jewel is in the fork the mov't will be running. If it's not, grab gently the rim and observer in which direction it's stopped. With practice this observation can be made also looking at the wheel spokes position. Lift gently a bit and rotate a tiny bit to the side it was blocked. It will start run away. 

4 minutes ago, OrbitalGolem said:
  • While watching Mark Lovick's Seiko and NH36A videos, he mounts the balance wheel and then rotates the balance bracket slightly counterclockwise to attach to the stud.  He seems to let the balance wheel hang freely.  Is that the preferred way of installing it?

Some people don't worry about letting the balance dangle briefly. Many others do, also because a dangly balance can catch into something. There are long running topics here about that. 

4 minutes ago, OrbitalGolem said:
  • Seiko/SII call out the "mirror finish" on the balance wheel/plate in the service manual.  Should I be using tweezers with rubberized grips?

Better would be brass or bronze tweezers.

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13 minutes ago, OrbitalGolem said:

Two additional questions:

  • When securing the balance plate, should I apply gentle pressure to the far end to "snap" it to the stud and then tighten the screw, or should I tighten the screw first?
  • Should the balance wheel start on its own before I tighten the plate screw?

The balance cock should be in its place including, stud in the hole, while you re-position the balance wheel. Of course it must run even without the screw being present.

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1 hour ago, OrbitalGolem said:

Hello everyone - I messed up the hairspring on a Seiko 4R36A when my tweezers slipped while moving the adjustment stud.  As the NH36A is identical to the 4R36A, readily available, and fairly inexpensive, I purchased a complete NH36A and transplanted its complete balance assembly.  I had both movements sitting next to each other, removed the balance plate screw, gently lifted the balance wheel from the plate, and very slowly moved the entire assembly with the balance wheel hanging freely to the other movement.

When it didn't start on its own after installation, I got really worried.  I had to re-fit it two more times until it finally started, but I suspect the new spring might be deformed slightly as the beat angle is low and I had to move the regulator (beat error) stud closer to the plate to keep it running.  Sigh.

I ordered another NH36A to try its balance assembly on the next attempt.  Some questions:

  • The hairspring for these models is crazy delicate - any tips/pointers how best to remove it?  Should I try to support it with another set of tweezers while moving it to the other movement?
  • Should I set the pallet fork to a specific position before the new balance wheel?
  • While watching Mark Lovick's Seiko and NH36A videos, he mounts the balance wheel and then rotates the balance bracket slightly counterclockwise to attach to the stud.  He seems to let the balance wheel hang freely.  Is that the preferred way of installing it?
  • Seiko/SII call out the "mirror finish" on the balance wheel/plate in the service manual.  Should I be using tweezers with rubberized grips?

Many thanks in advance.

 

1 hour ago, OrbitalGolem said:

Two additional questions:

  • When securing the balance plate, should I apply gentle pressure to the far end to "snap" it to the stud and then tighten the screw, or should I tighten the screw first?
  • Should the balance wheel start on its own before I tighten the plate screw?

I think you are using “stud” in the wrong sense. Either way you must make sure both balance pivots are evenly seated in their respective jewels before screwing anything down. The balance should be moving and ticking while screwing down the cock. Other wise you will surely not get a good seating and possible damage the pivots. Assuming it has power reserve still left If its not running when balance is seated then its not seated correctly, impulse jewel not seated in the pallet and/or Pivot/cock not seated correctly. Therefore you should not be screwing down anything.

you should let the balance dangle. Much easier. You first seat the balance wheel. When you do this the cock should be slightly angled out of the movement. This allows impulse jewel to seat in the pallet fork and bottom pivot in the jewel first. then you rotate the movement until the balance cock is lined up to where it needs to seat. Do not rotate the balance assembly in any way. You want to keep the balance steady in one position in your tweezers and maneuver the movement with your free hand to finagle cock into place, this method is much easier than Mark Lovicks way not to say his way is wrong either.

i find that letting down mainspring helps with seating the impulse jewel, but if there is power and action in the pallet set it so it points to the outside of the movement. Making it easier to go in from angle with the balance assembly

Edited by saswatch88
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2 hours ago, jdm said:

You replaced the balance cock, together with the balance of course. "balance complete" consists of the balance wheel (and staff) with the hairspring. There are two ways to that, one is with the balance dangling, another is using a (preferably wide tips) tweezers to gram wheel and cock as one part. This 2nd method is preferable only if the balance jewels have been removed already, otherwise with the balance pivots sitting at a forced angle in the hole jewels, there is a chance to bend them.

You should document your questions with pictures. Place the balance cock flat and the balance in the hole, short straight up with the best lighting and camera (phone) settings you can get.

I recommend that you practice on something cheaper than that, because at $40 a pop it becomes an expensive exercise quickly.

See answer above.

Too early for you to try that way. Just set the balance into the lower hole first. Then the upper hole, with the cock not fully set into it's posts yet. If the impulse jewel is in the fork the mov't will be running. If it's not, grab gently the rim and observer in which direction it's stopped. With practice this observation can be made also looking at the wheel spokes position. Lift gently a bit and rotate a tiny bit to the side it was blocked. It will start run away. 

Some people don't worry about letting the balance dangle briefly. Many others do, also because a dangly balance can catch into something. There are long running topics here about that. 

Better would be brass or bronze tweezers.

Many thanks!  This is my first significant repair and the wife is being exceedingly patient as this is a watch I bought for her.  :)

Looking at the SII service manual (page attached), I thought "balance complete" referred to the cock and balance wheel/hair-spring.  Yes, you're correct - I attempted to replace the balance cock with the balance/hair-spring.

I'll take pictures moving forward.  I'll post a few of how it looks now later tonight.  Reading your reply, I suspect that I may have bent the pivot ever so slightly as the wheel seems to stick when it reaches a particular rotational angle.

I ordered brass tweezers today and will use those moving forward.

One quick question:

  • How much pressure should I apply to the balance cock immediately above the upper post of the balance wheel when seating the wheel?  With the balance pivot being so fragile, I'm thinking I may have bent the first one, which is causing the wheel to stick.
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1 hour ago, saswatch88 said:

 

I think you are using “stud” in the wrong sense. Either way you must make sure both balance pivots are evenly seated in their respective jewels before screwing anything down. The balance should be moving and ticking while screwing down the cock. Other wise you will surely not get a good seating and possible damage the pivots. Assuming it has power reserve still left If its not running when balance is seated then its not seated correctly, impulse jewel not seated in the pallet and/or Pivot/cock not seated correctly. Therefore you should not be screwing down anything.

you should let the balance dangle. Much easier. You first seat the balance wheel. When you do this the cock should be slightly angled out of the movement. This allows impulse jewel to seat in the pallet fork and bottom pivot in the jewel first. then you rotate the movement until the balance cock is lined up to where it needs to seat. Do not rotate the balance assembly in any way. You want to keep the balance steady in one position in your tweezers and maneuver the movement with your free hand to finagle cock into place, this method is much easier than Mark Lovicks way not to say his way is wrong either.

i find that letting down mainspring helps with seating the impulse jewel, but if there is power and action in the pallet set it so it points to the outside of the movement. Making it easier to go in from angle with the balance assembly

Many thanks for the reply.  I'll let the balance dangle on my next attempt.

Re: your last paragraph, is it best for me to have power in the main-spring when doing this?  Per your comment that the pallet should be pointing to the outside of the movement, I realize now that I had it in the wrong position, pointing "up" rather than "out" with the movement positioned such that the balance wheel is on the right-hand side.

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4 minutes ago, OrbitalGolem said:

I'll take pictures moving forward.  I'll post a few of how it looks now later tonight.  Reading your reply, I suspect that I may have bent the pivot ever so slightly as the wheel seems to stick when it reaches a particular rotational angle.

That is not enough to tell. You would need to remove the balance from the cock and examine both pivots carefully from all angles.

4 minutes ago, OrbitalGolem said:
  • How much pressure should I apply to the balance cock immediately above the upper post of the balance wheel when seating the wheel?  With the balance pivot being so fragile, I'm thinking I may have bent the first one, which is causing the wheel to stick.

No pressure, it must fall in place by itself. 

I do not recommend that you let balance dangle unless you're ready to sacrifice yet another one. Seiko hairspring do not tolerate any mistreat.

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40 minutes ago, jdm said:

That is not enough to tell. You would need to remove the balance from the cock and examine both pivots carefully from all angles.

No pressure, it must fall in place by itself. 

I do not recommend that you let balance dangle unless you're ready to sacrifice yet another one. Seiko hairspring do not tolerate any mistreat.

Understood.  Per your earlier comment about this (below), I should then use a larger pair of tweezers to hold both the balance cock and wheel?

"There are two ways to that, one is with the balance dangling, another is using a (preferably wide tips) tweezers to gram wheel and cock as one part. This 2nd method is preferable only if the balance jewels have been removed already, otherwise with the balance pivots sitting at a forced angle in the hole jewels, there is a chance to bend them."

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2 hours ago, OrbitalGolem said:

Many thanks for the reply.  I'll let the balance dangle on my next attempt.

Re: your last paragraph, is it best for me to have power in the main-spring when doing this?  Per your comment that the pallet should be pointing to the outside of the movement, I realize now that I had it in the wrong position, pointing "up" rather than "out" with the movement positioned such that the balance wheel is on the right-hand side.

Having power in the mainspring is up to you, but letting it down with the click spring makes it easier because when it has power you can make it bank to the other side when trying to seat the impulse/roller jewel.

Although the way to hold the balance assembly is highly subjective, letting balance dangle for the only purpose of installing you will not have any issues with Seiko. i can guarantee you will be more likely to damage the pivot or the hairspring trying to hold the assembly together with tweezers, this method requires a level of skill. I just would not let the balance dangle on a tack unless necessary and for only short period. Seikos are the very first watches i started working on and this is the way i did it for years never had any issues.

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