Unknown fossil service

[Terrinecold]

I am trying to service this watch. 
It is a fossil between 15 and 20 years old. 
The back of the case say AM-4031 110606

I have included pictures of the case back and movement. 
 

The inside of the case says fossil china. 
The movement says 21 jewels adjusted Japan. 
 

It is unidirectionally winding. So I think it may be a Miyota but it doesn’t look like an 8215 or derivative. 
 

I’d like to not break it so I am taking it slowly. Right now I am unsure how to remove the rotor. There is one obvious screw accessible for that but there is also another one which is visible which I can’t reach. 
 

I am also trying to figure out how to remove the stem. 
 

I’ll keep you updated 

 

 

I managed to remove the crown and the movement from the case

Removed from the “ring dial” not sure how to call the metal bit with the minute markers. I still haven’t figured out how to remove the rotor. I think I need to remove the plastic spacer to remove the dial

I didn’t need to remove the spacer the feet screws were accessible through holes in the plastic spacer 

I removed the screws which I could hoping to separate an automatic winding bridge. But instead it was a Miyota style cover everything bridge. I still haven’t figured out how to remove the rotor. I am starting to think I need a dedicated tool. There are a couple of flats on the center of the rotor where I would have expected a screw. I am guessing some special wrench is needed there. 
Indirect center second pinion. It looks like a Miyota but I am not sure which one

I have now disassembled everything I could I still don’t know what to do with the rotor and main bridge there is no way I can put that bridge back with the rotor still on. 
 

I also still don’t know what movement it is. The rotor says it is Japanese and there are some similarities with Miyota 8215:

single bridge design, unidirectional winding, indirect central second. But the look of the bridge and a bunch of details don’t match. Any help there would also be appreciated 

[nevenbekriev]

https://miyotamovement.com/product/6T28/

The internal part of the rotor bearing is a nut that is tighten on a threaded post that sits on the middle of the bridge. You need to unscrew it, just like You have tried, but with more proper tool.

[Terrinecold]

Thanks for the confirmation I think I have the 6T15-1TH*
 

https://miyotamovement.com/product/6T15/
as there is that small 6 o clock date. I looked for it all yesterday knowing it was likely a Miyota but didn’t find it till your reply. It is close to the 6T28. 
Now I’ll try to find a tool which will work. 

I don’t have much capability to fabricate things. I have a friend with a 3D printer do you think it could be used to make a tool precise and rigid enough?

Interestingly the movement pictures I see have a screwdriver slot in the nut which monde doesn’t. I wonder if I could add that with a dremel or hand file. 

On a different note asI es typing my microscope camera arrived hopefully I’ll be able to make better pictures

Except it looks like I ordered the wrong adapter for it

[caseback]

Some of those very cheap screwdriver set actually have a selection of small size wrenches:

[Terrinecold]

@caseback indeed.  I'll check the exact dimension tonight.

I did find this

https://www.amazon.com/Moody-58-0161-8-Piece-Metric-Wrench/dp/B003HGHU9I/ref=sr_1_1?crid=12RW2VFWH854D&dib=eyJ2IjoiMSJ9.vzl7Co7oEUunyeCWTks5tyYb0yJ9mH2s3hQAtN7UMQXGjHj071QN20LucGBJIEps.FaOnyG9Gm2rjwd8I5Z1D-vb03j00YbWhzSHV4hgDHUI&dib_tag=se&keywords=Moody+58-0161&qid=1717445510&sprefix=moody+58-0161%2Caps%2C106&sr=8-1

It is fairly cheap but only about 25% cheaper than a new 6T15 movement so worth it only if I will use it more than this once.

Has there been other cases where you had to use a wrench inside a watch movement?

Edited June 3, 2024 by Terrinecold
adding information

[caseback]

44 minutes ago, Terrinecold said:

@caseback 

Has there been other cases where you had to use a wrench inside a watch movement?

Nope, only on several Japanese automatic movements. I can't remember if they were all Citizen's. There might have been some Ricoh's or Seiko's with a simular construction as well.

[Terrinecold]

I measured the width at 2.05mm. The smallest wrench I have found so far is 2.5mm.  
 

Just found that the imperial set has a 5/64” which will be just a tiny bit too small but a file should be able to fix that

 

[nevenbekriev]

Guys, do You believe that the 'nut' pops up above the rotor surface enough to be cought by a wrench?

[HectorLooi]

Why all the fuss? I just use a big eyebrow tweezer to grip it and it works fine. The eyebrow tweezer also works great for replacing Chinese Incabloc springs that fall out.

[Terrinecold]

I can try a big tweezer the biggest I had in my set didn’t do the trick but I’ll check if my wife has some none watchmaking ones. 

[Terrinecold]

I received the small wrenches and they are useless the smallest one 5/64 which is supposed to be smaller than what O need os actually bigger. 
The tweezers method didn’t work I couldn’t found any sturdy enough to unscrew the thing. Right now I am giving up. I think the only way would be to dremel a slot in the bolt as the newer version of the same movement seem to have but I don’t want to go though that, I don’t have a way to hold the piece and I don’t think I can be precise enough with a demel. 

[AndyGSi]

Looks like you need what's called a H Blade or maybe just file a slot in a 2mm Screwdriver.

https://www.cousinsuk.com/product/hublot-bezel-screw1

[HectorLooi]

38 minutes ago, Terrinecold said:

The tweezers method didn’t work I couldn’t found any sturdy enough to unscrew the thing.

Use this type of eyebrow tweezers. The angled jaw type gives better torque than the straight ones.

[Terrinecold]

I showed the picture to my wife she says she has some. I’ll try thanks 

@HectorLooi I showed the picture to my wife she says she has some. I’ll try thanks    
 

@AndyGSi

2 hours ago, AndyGSi said:

Looks like you need what's called a H Blade or maybe just file a slot in a 2mm Screwdriver.

https://www.cousinsuk.com/product/hublot-bezel-screw1

there is no slot and that is the problem I don’t see how either would help. 
As I mentioned all versions of this movement I saw for sale do have a slot bridging the gap and either of those would work but the one I have does not 

[nevenbekriev]

Take a rod that is bigger in diameter than the nut but is smaller than internal diameter of the outer bearing ring. File a slot in it.

[AndyGSi]

56 minutes ago, Terrinecold said:

I showed the picture to my wife she says she has some. I’ll try thanks 

@HectorLooi I showed the picture to my wife she says she has some. I’ll try thanks    
 

@AndyGSi

there is no slot and that is the problem I don’t see how either would help. 
As I mentioned all versions of this movement I saw for sale do have a slot bridging the gap and either of those would work but the one I have does not 

The idea is the slot in the end of the screwdriver would fit the flats to unscrew it so if you're saying it 2mm then would need to be a 3mm or larger.

[AndyGSi]

The smallest one of these may work.

 

[Terrinecold]

The tweezers for eyebrows worked 

 

thanks every body. It is really great to have such incredible help and support. 

[Terrinecold]

2 hours ago, nevenbekriev said:

Take a rod that is bigger in diameter than the nut but is smaller than internal diameter of the outer bearing ring. File a slot in it.

I think that would have worked but the tweezers did the job. 
 

On 6/4/2024 at 2:13 AM, nevenbekriev said:

Guys, do You believe that the 'nut' pops up above the rotor surface enough to be cought by a wrench?

It didn’t. It did pop out a tiny bit but not enough for the wrench 

[Terrinecold]

I hope I took enough pictures. I am now going to clean everything and I am pretty uncertain about my ability to put it all back together. 
The basic movement should be ok with likely some frustration when putting the big bridge on. But both the calendar side and the automatic parts will be stressful. Specially since everything is so tiny compared to the ST36

so many more parts

This 2 will be of great help.  The Miyota site actually provides them

This part is called “date dial guard” in the Miyota chart. As you can see there is a wheel and some kind of spring/jumper on it which I don’t think I can remove.  I also don’t see them in the assembly - disassembly chart. 
Do you think I am correct it is supposed to stay together and I shouldn’t try to disassemble it further?

[Terrinecold]

Good progress made on the assembly. 
Next step the barrel (and gear train ) bridge 

 

time to breath a bit and go rock climbing. 

Interestingly lots of place where I thought one would put some oil (hp) Miyota recommends grease:

center wheel pivots. 
Driving gear for ratchet wheel pivots

reduction wheel pivots

[Terrinecold]

Well I can't always report good progress.

I just spent an hour trying to set the barrel bridge.  That is one bridge which goes over:

The barrel

The driving gear for ratchet wheel

Reduction wheel

sweep second pinion (which is on a spring)

Third wheel and pinion

fourth wheel and pinion

escape wheel

I still haven't managed to do it.

In particular, most wheels I can jiggle a bit to make their pinion go into the jewels but the sweep second pinion and the fourth wheel are not accessible once the bridge is in place and everything else is good.

Does anybody have suggestion?  I have already reassembled a Miyota clone but it was also a bit bigger than this movement which is a pretty small one

[HectorLooi]

Don't give up. You just need patience and practice. Don't use force or try to screw down the plate before making sure everything is in place.

My first few watches took me like 45 minutes to get the train wheels in. Now it usually takes me less than a minute.

Make sure that all the bottom pivots are in their respective holes before putting on the top plate. Then apply gentle pressure with a pegwood or gloved finger. Start from the barrel, 2nd wheel, 3rd wheel.... and finally the escape wheel. You can feel the plate drop each time you get a pivot in.

If you experience the pivots that you have already gotten in coming out of their holes when you work on other wheels down line, you can put 1 or 2 screws nearer the barrel side in but don't exert any force on the screws. Just lightly turn the screws until you feel pressure and backoff 1/4 turn. This will prevent the plates from separating. 

I use a homemade tool with a brass wire, shaped like an oiler to lightly touch the wheels to guide them into place. I find that an oiler made of hardened steel can leave scratches on the brass wheels.

Once you think you have gotten all the pivots in, test it by using a blower to blow on the escape wheel. It should spin freely. Continue applying pressure on the top plate with the pegwood or finger until you lightly tighten all the screws. Don't tighten fully yet until you reconfirm that the wheels are able to spin freely. And reconfirm again after you have fully tightened all the screws.

What you are experiencing is normal. All of us have gone through it. Don't work on watches when you are tired or frustrated. All of us can tell you what that leads to. But I'm sure you'll experience a few hard lessons even after reading this advice. It's only human.

Go forth and practice. Good luck!

Edited June 13, 2024 by HectorLooi
Typo

[Terrinecold]

Thanks Hector,

I do think though that the problem I am experiencing is specific to Miyota movement in general and the 6T series in particular.  When you describe putting the bridge you are talking about the train wheels.  The problem here is that under that same bridge you have the 4 train wheel, the barrel, 2 extra winding related wheels and the center sweep pinion.  I can mostly put them in their holes but 2 of those (the 4th wheel and the second pinion are completely under the plate so I can't nudge them in the right position.  

I managed it with a larger Miyota 8200 series but with the smaller 6T15 it is even worse.

Anyway, I'll retry tomorrow evening or this week end.  This evening is going another rock climbing day (going from very light pressure on tweezers to much more force going through the fingers, although in climbing we also want to use the absolute minimum grip which won't make us fall to save the muscle and be able to climb longer routes).

to add insults to injury, if you read this thread from the start, I initially messed up the disassembly as I couldn't detach the rotor.  I normally (and I think I did this time too) put all my parts in their individual compartments in the part tray and I am doing my best to be very careful about them.  But in the week and a half it took to figure out how to detach the rotor I somehow lost the screws from the bridge.  I have a few others which will be needed later.  I know they are reference 922-600 but I couldn't find what it means in general term so I don't know if I can buy replacements or an assortment of screws and replace those 2 by others.

[caseback]

You could try the "tapping method". Don't put any pressure on the bridge and just tap the side of the movement holder until the pivots find their place. It often works.

If there is some kind of click mechanism putting pressure on one of the wheels (like the 8200 has if I remember right), use a bit of rodico to keep the click "open" and remove it later.