The most stuck of stuck casebacks.

[Birbdad]

I bought a junk watch for cheap to get the seiko 7006 within it and it has a very odd construction. 
You can see a guy open it here 

The case back is two parts, a ring and something else underneath it. If i put so much pressure on that caseback to open it that it starts to sheer metal off the case opener slots it spins about 15 degrees and comes to a total stop. I cannot for the life of me conceive of how a caseback can be THIS stuck. I have a case vice and a jaxa tool. I do not currently have a professional rack type opener but i can get a good purchase on the jaxa. THis thing is so stuck i'm pretty sure it's gonna break the teeth on the jaxa before it opens. Only real advice i could find was about supergluiing the casback to a nut and then turning the nut> This obviously won't work with the two part caseback constrution. 
Any ideas? 

 
 

[Waggy]

Double bag the whole movement and place it in a coffee mug of hot water and let it sit there for a while, as soon as the case has reached the same temperature as the water you can remove it - this will expand the metal. Quickly place an ice cube on the case back/ring and give it a few seconds to cool this part. Now you should have an expanded case and a contracted case back reducing the surface contact area of the treads and hopefully breaking any bonding between them. Now give it your best shot to torque off the case back... and if at first you don't succeed...

[Birbdad]

10 minutes ago, Waggy said:

Double bag the whole movement and place it in a coffee mug of hot water and let it sit there for a while, as soon as the case has reached the same temperature as the water you can remove it - this will expand the metal. Quickly place an ice cube on the case back/ring and give it a few seconds to cool this part. Now you should have an expanded case and a contracted case back reducing the surface contact area of the treads and hopefully breaking any bonding between them. Now give it your best shot to torque off the case back... and if at first you don't succeed...

Well this makes me nervous because i'm 100% certain this case is not waterproof anymore and if that doesn't work i'm gonna have the spare movement inside rusting away. I'll file that one away in last resort territory. 

[Waggy]

ha ha, you could triple bag it before putting it in water

[Birbdad]

2 hours ago, Waggy said:

ha ha, you could triple bag it before putting it in water

oh haha, i missed where you said double bag

I could give that a shot thanks man.

[RichardHarris123]

Let us know if it works. 

[watchweasol]

Hi.  A tried and tested method is to superglue a large nut to the case back and I’m when solid use a long spanner or wrench and unscrew.  Ihave used this method several times and had no failures. To remove the place the back in acetone, it dissolves the glue and the nut falls off and clean off the back, job done.

[Birbdad]

8 hours ago, watchweasol said:

Hi.  A tried and tested method is to superglue a large nut to the case back and I’m when solid use a long spanner or wrench and unscrew.  Ihave used this method several times and had no failures. To remove the place the back in acetone, it dissolves the glue and the nut falls off and clean off the back, job done.

Yeah i searched here and saw this but the problem is this has a two piece caseback. The slots to unscrew it are on a ring that is separate from the flat part of the caseback. 

 

11 hours ago, RichardHarris123 said:

Let us know if it works. 

I'll try this first since it's non destructive but i got a bit of info about it that makes me think that probably won't work.  I met a professional watchmaker in belgium who said he's had a bunch of these on  his bench and they are notorious for seizing up and cold welding. He says half of the ones he's gotten on his bench the only way he could get them off was to jam a screwdriver into the slots and hammer it to unscrew. 

[HectorLooi]

I've worked on a lot of Russian watches with similar two piece casebacks. The trick is to wet the back with water and let the water soften the organic gunk and dried up sweat. WD40 doesn't seem to work in this instance.

Instead of the Jaxa, I use a cheap, 2 pronged tool from China. The tip has to be ground down to fit into the notch snugly. 

[Endeavor]

I also worked on a lot of Russian watches, same back-lid closing principle. Nearly 99.9% of the time, I'm using only two slots of my jaxa-tool, which gives you the same tool as above, HectorLooi recommends.

It could be that the screw-ring is cross threaded or worse, was damaged and glued ?? You could try some acetone? But with this screw-ring/back-lid I've never encountered the mother of all the stucknesses

Suc6 !!

 

[Marc]

On 3/22/2023 at 7:29 AM, Birbdad said:

it spins about 15 degrees and comes to a total stop

I'm not familiar with this design on a Seiko (plenty so with the Russian watches) but a thought occurs...  If the retaining ring rotates 15 degrees and then comes to a complete stop and won't go any further, is it possible that this case back uses a bayonet style closure rather than a thread? In which case (no pun intended) trying to rotate it further would be futile, and all it would need once turned to the open position would be to lift it or gently pry it up if it is a bit gunked up. May be worth a try.

[mikepilk]

According to the Seiko Casing Guide, the 7006-500 has a Square-3 type casing . 

[Birbdad]

1 hour ago, mikepilk said:

According to the Seiko Casing Guide, the 7006-500 has a Square-3 type casing . 

So this is so bizarre but that information is wrong. The information for my other seiko project is also wrong in that same casing guide. It's so weird. I got that guide to see if it would help and both this watch and my other project's case codes are listed in there and neither are correct lol.

Edited March 23, 2023 by Birbdad

[mikepilk]

Very weird the Casing Guide being so wrong.

I'd put some WD40 around the back and leave it over night, Clean it off with IPA or similar, so it's not too slippery. Then try @Waggy's hot drink trick. 

If you can find a way of holding the case securely, and have something relatively soft like a brass rod, you could try a sideways tap with a hammer on one of the notches. It might break the stiction.

[Birbdad]

22 minutes ago, mikepilk said:

Very weird the Casing Guide being so wrong.

I'd put some WD40 around the back and leave it over night, Clean it off with IPA or similar, so it's not too slippery. Then try @Waggy's hot drink trick. 

If you can find a way of holding the case securely, and have something relatively soft like a brass rod, you could try a sideways tap with a hammer on one of the notches. It might break the stiction.

this saturday i'm gonna go at it. i'll report back. And yeah it si weird about the casing guide. If you watch the vid i posted in the OP you can see the weird two piece case back. Iv'e never seen a system like that.

[RichardHarris123]

Why were two piece backs made, doesn't seem to be any advantage. 

[Endeavor]

1 hour ago, RichardHarris123 said:

Why were two piece backs made, doesn't seem to be any advantage. 

If you were to study the Vostok Amphibia, how the Russians designed a far more clever & far more superior water-resistance watch, you would understand

[Birbdad]

1 hour ago, RichardHarris123 said:

Why were two piece backs made, doesn't seem to be any advantage. 

GOOD QUESTION. IF what that one watchmaker said about them i can see why they ditched them pretty fast.

[rehajm]

With that design you're really looking more for the bezel removal tricks. Perhaps the little jam jar lid embedded in a bead from the hot glue gun? I've been waiting for an opportunity to try that one! 

[tomh207]

Best bet I think would be a good case vice in a fixed or at least heavy vice then try the tools you have again if that fails the a small brass drift and brass hammer to get it started. 
 

next we’ll be recommending an angle grinder

 

Tom

[RichardHarris123]

I watched a video of someone servicing a fake Rolex , after he had finished, he tested out his grinder.  Hehe. 

[Neverenoughwatches]

1 hour ago, RichardHarris123 said:

I watched a video of someone servicing a fake Rolex , after he had finished, he tested out his grinder.  Hehe. 

That was Mark our host . 

5 hours ago, Birbdad said:

this saturday i'm gonna go at it. i'll report back. And yeah it si weird about the casing guide. If you watch the vid i posted in the OP you can see the weird two piece case back. Iv'e never seen a system like that.

Ok so Col just noticed your thread. I dont know if this is relative to your seiko. But my dad's 70s Russian Sekonda quartz has a ring like this holding a case back plate in position. The plate has a tab that locates into a groove in the case itself to stop the plate from spinning as you undo the ring. The removal notches on the ring were quite small so i had shape the jaxa pins to fit. The ring was very tight, after some pussy footing around i eventually bit the bullet and gave it some welly. Maybe not the best approach but it did give in to my hands of steel.