Seiko 7S26C assembly woes

[RobBrandywine]

So, I partially disassembled the movement just far enough to get the new mainspring barrel I ordered in plus I removed the balance to keep it from getting damaged.  I made a rookie mistake when doing this in that I flipped the watch over to look at something on the dial side and 4 parts fell off , which I determined to be the old barrel, the clickspring, and the 3rd and 4th wheels.  So, I didn't get to look at where the 3rd and 4th wheel were seated.  I finally figured this out and got to the point of replacing the train of wheel/automatic works bridge.  So far so good.  But I couldn't get the bridge to seat fully at all 3 screws.  Whichever two I got to seat, the 3rd one wouldn't seat fully.  So I removed the bridge and was making sure all the wheels would turn as they're supposed to.  The 1st, 2nd, 3rd, and 4th wheels all turn but the escape wheel doesn't.  I noticed that the pinion gear of the escape wheel isn't held in place at this point.  When the 4th wheel turns, the pinion gear just kind of moves to the side, out of contact with the 4th gear teeth.  Is this normal?  Do I have to get the bridge seated for that pinion gear to be held against the 4th wheel?  Finally, with the 4th gear removed should I be able to turn the escape wheel or does it depend on it's pivot being held?  Thanks for any help!

[watchweasol]

Hi. A bit of a pickle indeed.  Thing to do is back check what you have done so far , then dismantle it again noting where the parts come from , take pictures,  check the plate filling without the wheels, check the wheel pivots are intact as clumsy fitting can snap them off very easily, in your case inspect the escape wheel pivots closely then re assemble carefully.  Parts/data sheets can be found at CousinsUk material house under documen5 downloads.

[eccentric59]

What scares me is the statement "I couldn't get the bridge to seat fully at all 3 screws." You don't seat the bridge with the screws, you secure the bridge with the screws once the bridge is seated and all pivots are in their respective jewels. Trying to tighten the bridge screws when the wheels aren't turning freely is an invitation to a broken or bent pivot. You might want to take a close look at the escape wheel because that definitely should engage with the 4th wheel when seated.

Do you have the data sheet for the 7S26A? If not here you go: https://seikoserviceusa.com/uploads/datasheets/7S26A&7S36A.pdf

[RobBrandywine]

What I did was screw in all 3 screws, slightly.  Then I would lift and lower the bridge and check to see if the bridge was properly lowered in to place.  I could never get it in what I considered a fully lowered position. Of course, there's always the possibility that I am  too cautious in what to expect.  But I'm not willing to try to screw it down at this time.

It's a good suggestion to remove the 3rd and 4th wheels and see how far down the bridge goes. 

[JackH]

One thing to check is if the click is wedged under the bridge. It should be outside the edge. When I first started, I had it caught under the bridge and took me a while to find it.

Edited February 3 by JackH

[watchweasol]

Hi what Jack says is right that’s why I suggested fitting the plate without a thing else to appreciate how it fits and Ger the feel of it as it fits,  then start reassembling again checking out each abs every step

[rossjackson01]

Getting quite good with my 7S26's now. I knackered at least 4 on my learning curve. Been learning just over 25 month.

System

All parts oiled as per Seiko chart. I use the maxim from Mike of Myretrowatches. If you can see it on the oiler, it is too much.

Centre wheel and then bridge. Insert barrel. Rotate barrel to see centre wheel ok. 

3rd wheel. 4th wheel and escape wheel into relevant correct locations. Gentle touch on barrel to if all move. Don't spin it much as it will dislocate the wheels.

Pawl lever parts fitted correctly to Barrel train wheel bridge. Make sure pawl lever is inserted correct way.

Offer Barrel train wheel to plate. Move click and allow it to settle. Move it gently over pivots. It it doesn't settle, then I usually rap tap the holder with the top end of the tweezers. This allows, sometimes, the pivots to find their respective holes.

Even if I think all is ok. I gently hold the barrel with pegwood and gently move the mainspring barrel. If all OK.

Put a screw into a holding hole. 1 or 2 winds. Check rotation on the mainspring barrel. If ok, wind down to small bind. Check again. Do the same to two other screws. If all ok, by checking with mainspring winder rotation, secure each screw separately and check wind. I have had it where on the final tightening of a single screw the wheel bound. Ease off. Try wind. Only when happy, secure all.

Check rotation again.

I've been lucky with my last two 7S2's. Both had the barrel bridge settle as I offered to to the plate. Flaming amazing. But they were virgin watches. Had never been opened before.

All three watches prior took me over 2 hours each time. All working now. But 'gentle' is the name of the operation. Not damage a pivot for nearly a year now. Phew!

Movement is now working well. Case cleaned. New crystal to be ordered tomorrow.

 

Note

Don't despair.

Consider the alternative to damage

Have a break. Coffee. Go shopping with bride if you have one. Show her your problem. Maybe  she will not understand. But letting your bride into what you are doing is a great show of trust. It was she who learned to say to me the lifesaver, "Don't ping. Coffee". I'd come back. Flaming thing would often go in ok. She would smile that knowing smile. 

Hope this helps

Great hobby this.

Edited February 3 by rossjackson01
Spelling, Grammar

[JackH]

6 hours ago, watchweasol said:

Hi what Jack says is right that’s why I suggested fitting the plate without a thing else to appreciate how it fits and Ger the feel of it as it fits,  then start reassembling again checking out each abs every step

The click trapped under the bridge issue got me a few times when I was starting out. I also struggled with the tiny diafix cap jewels. 

[RobBrandywine]

Bingo JackH.  I had just come to post that it was fitting down now and all I could figure was that I had the click under the bridge. 

  But I'm going to have to take it back apart to see why the escape wheel doesn't turn.  Also, AFAICT, the center hole of the rachet wheel is circular, not square.  Is that normal? Or maybe I just need to look at it under more magnification?

Edited February 3 by RobBrandywine

[Malocchio]

2 hours ago, RobBrandywine said:

 But I'm going to have to take it back apart to see why the escape wheel doesn't turn.  Also, AFAICT, the center hole of the rachet wheel is circular, not square.  Is that normal? Or maybe I just need to look at it under more magnification?

It's not completely circular, there are two straight sides opposite each other. The escape wheel might have a pivot missing. I snapped one when learning stuff the hard way. I also snapped a pallet fork pivot. You have to be absolutely certain before tightening the screws. Keep very light pressure on the bridge with a peg wood while turning the wheels to make sure every pivot is in its hole. Maintain the pressure while tightening screws.

[watchweasol]

Hi. When you think the bridge is correctly fitting check the end shake on the wheels they should all lift and drop under their own weight then fit the screws and continue checking the drop whilst tightening down the screws. 

[JackH]

3 hours ago, RobBrandywine said:

Bingo JackH.  I had just come to post that it was fitting down now and all I could figure was that I had the click under the bridge. 

  But I'm going to have to take it back apart to see why the escape wheel doesn't turn.  Also, AFAICT, the center hole of the rachet wheel is circular, not square.  Is that normal? Or maybe I just need to look at it under more magnification?

I am happy to be able to help. This happened to me too. I finally learned to pull the click aside slightly while installing the bridge.

[rossjackson01]

Not sure if you have the Seiko 7S26c guide

 

7S26C_36C_tech_guide_update.pdf

Edited February 3 by rossjackson01

[RobBrandywine]

I gave things a couple of days and restarted.  I took things down part way (same as I did before).  The center wheel and bridge are still in place along with the Pallet cock, pallet fork, and escape wheel.  I can turn the escape wheel with tweezers and the pivot looks fine,  I can also turn the center wheel with tweezers.  I want next to install the barrel and see if turning it turns the center wheel.  My question is, given the above is it necessary to disassemble any further?

I'll be using rossjackson01's tips as I go along.

[watchweasol]

Hi. So the situation’at the moment is that all wheels installed and their respective bridges and all rotate freely, yes and now you want to install the barrel, yes.  If you have sufficient clearance and space ok but you may need to shuffle abit to get the barrel bridge on and don’t forget the click spring.

[RobBrandywine]

Not exactly, all I have installed is the 2nd wheel with it's standalone bridge and the escape wheel with the pallet cock (using Seiko's terminology).  Those two wheels spin. with tweezers. Installing the barrel next to check the spin of the 2nd wheel is JackRoss01's way of doing it and I think it sounds like a good second check of the 2nd wheels ability to spin.

[RobBrandywine]

I  got back to where I was before -- putting the train wheel bridge on.  I must say I'm not having any fun.  This may not be the hobby for me. I've made about 25 attempts now and twice I've got it down to where the train moves, but both times I fumbled with the first screw and the train froze again.

[rossjackson01]

Rob

Got news for you. You are definitely the man for the hobby. What you are doing, exactly as I did, is learning to get you motor skill correct. You will probably do quite a few more 'flaming hecks' before you get to the lighter touch sensation stage. 

I'm as the stage where I can 'feel' the screws. You don't know that you are getting there, but I can assure you, you are. Even last week I had to remove a bridge 4 times, even though every wheel did spin nicely, it did not 'feel' good. On one occasion I thought the pallet fork was the culprit. Took it out and, 'well I never'. That train doesn't feel right. Try again.  Feels good on the spin now. Tomorrow's job. Rebuild the dial side. It's another Seiko. A Bellmatic 4006. Same principles as the 7S26 on the trainwheel bridge. 

Don't forget, you can tell us what you are doing and what you feel. And, hey! You'll get the feedback to tell you that we have all been there, and still do the same even now.

Great pleasure in this hobby. Good man you are.

Edited February 6 by rossjackson01
More information

[Waggy]

Just to pick up a point on installing the train of wheels bridge. On the YouTube channel from weekend watch repair you see him using a technique where he rapidly taps the movement holder with his tweezers to get the wheels to sit in their jewels. I have copied this and around 75% of the time it works and removes hours of heartache (well it seems like hours at the time). You can see him doing it on most of his videos.

Link to the channel below

https://www.youtube.com/channel/UCRmSkqKTlLVf9epzW95OaoA

[nevenbekriev]

Well. I read and wonder... The lever is in the movement with it,s cock, then why You expect the train is going to spin??? Take off the lever, then try again

[Neverenoughwatches]

5 hours ago, Waggy said:

Just to pick up a point on installing the train of wheels bridge. On the YouTube channel from weekend watch repair you see him using a technique where he rapidly taps the movement holder with his tweezers to get the wheels to sit in their jewels. I have copied this and around 75% of the time it works and removes hours of heartache (well it seems like hours at the time). You can see him doing it on most of his videos.

Link to the channel below

https://www.youtube.com/channel/UCRmSkqKTlLVf9epzW95OaoA

That would be our very own big hammer guy Thor.  ( Adam ) hes come a long way, wish him all the best with his channel .

[rossjackson01]

8 hours ago, Waggy said:

Just to pick up a point on installing the train of wheels bridge. On the YouTube channel from weekend watch repair you see him using a technique where he rapidly taps the movement holder with his tweezers to get the wheels to sit in their jewels. I have copied this and around 75% of the time it works and removes hours of heartache (well it seems like hours at the time). You can see him doing it on most of his videos.

Link to the channel below

https://www.youtube.com/channel/UCRmSkqKTlLVf9epzW95OaoA

Use that method all the time now. Most effective. As you say 75% is a good representation. It's the other 25% that I feel like getting the big hammer. But I don't.

[RobBrandywine]

18 hours ago, nevenbekriev said:

Well. I read and wonder... The lever is in the movement with it,s cock, then why You expect the train is going to spin??? Take off the lever, then try again

What do you mean by lever?  The train of wheels is complete down to and thru the pallet fork; the balance wheel is removed. Shouldn't be train of wheels be free and just move the pallet fork back and forth? And it does move - without the bridge on, and twice, with the bridge on.

[steve855]

@nevenbekriev gave us the key to this one.

Pallet fork will keep the escape wheel from turning freely, that is its job. With the balance in place and oscillating, pallet lets the escape wheel, and thus the rest of the train, move in small steps.

I think trying to install train wheel bridge with pallet fork in place is making it more difficult than it needs to be.  Also runs the risk of dislodging a pallet stone if the escape wheel pushes down on it when trying to assemble.

I think it will be much easier if you remove the pallet fork and its bridge before installing train wheels and bridge.  Then you can check that the train spins freely.  Stick with it, you'll get there.  Eventually it will all just fall into place and you'll say "aha!"

just don't force it.  

[nevenbekriev]

6 hours ago, RobBrandywine said:

What do you mean by lever?  The train of wheels is complete down to and thru the pallet fork; the balance wheel is removed. Shouldn't be train of wheels be free and just move the pallet fork back and forth? And it does move - without the bridge on, and twice, with the bridge on.

By lever I meen pallet fork.

See, I am not sure what You mean by this:

On 2/5/2024 at 7:11 PM, RobBrandywine said:

... The center wheel and bridge are still in place along with the Pallet cock, pallet fork, and escape wheel.  I can turn the escape wheel with tweezers and the pivot looks fine...

 

But if the pallet fork is in the movement, take it out. There are videos that show how some idiot starts assemly of the movement with putting the lever in place. Do not learn from them...