Help for crystal change on a rather rare watch ?

[Endeavor]

Hallo All;

I'm facing a bit of a challenge, one of those "no-room-for-any-error" .......

I bought a "MIR" 15-years in orbit commemorative Poljot 3133 chronograph (Housing+movement) for spare parts. After the purchase I started reading about this model and it turns out that only 104 of these were made. Of these 104, according to the Polmax3133 website (http://www.polmax3133.com/gallery0101_mir2001.html), only watch #035-104 and #070--104 are known to the writer. I do have #026 - 104 and with the original "never-seen" convex case-back.

 

The watch is in poor health; heavily scratched case, back-cover, bezel & crystal, a pusher missing, wrong crown, balance-assembly (apart from the cock) missing and a very dirty movement.

I managed to buy a rather expensive identical year 2001-2005 NOS housing with the correct pushers and crown for the MIR-watch, but the new housing doesn't have the original Tachymeter-ring. Also, since I'm now planning on using the old numbered case the pushers, crown, crystal and tachymeter-ring (and perhaps the bezel) have to be swapped.

The only way to get the tachymeter ring out is through the front. Assuming that the crystal could take some force, I pressed with my thumbs from the inside against the old crystal and before I knew, glass scattered all over the place. It turns out that the crystal was only 1mm thick and made out of mineral glass

As said, the new housing was rather expensive and I can't afford to brake the new crystal. The new housing is still in transit, so I can only describe the setting of the old crystal. It seems that the crystal was captured (or press-fit) in a sort of nylon/plastic ring between the housing and crystal. I can't measure the exact size of the old-crystal anymore; 1000 pieces.

My questions are;

1) how to get safely the new crystal and nylon/plastic ring out of the new housing (I do have a hand-press with dies, if that is what is needed?)

2) can the crystal be swapped, re-using the nylon/plastic ring out of the new housing?

3) as a back-up plan, what needs to be known about the crystal before attempting to push it out? (Thinking of, if possible, trying to get the crystal diameter still seated if that's close enough ??)

4) In case it goes wrong, what can be done? Who has similar crystals (CousinsUK?) and those nylon/plastic rings ? Are they rather common (the ID of the housing is 29.94mm and the old nylon/plastic ring (not compressed) appears to be 0.4mm thick material)?

5) Can the crystal-size be calculate backwards from the housing ID, back from the 29.94mm?

6) Other do's, don'ts & watch-out fors tips are very welcome ......

Hope to hear your expertise / experiences ......

 

 

 

Edited October 27, 2019 by Endeavor

[watchweasol]

Hi  Esslinger web site gives a good insight to the fitting and measuring of crystals in the from of a tutorial. well worth a look before going any further.

[Endeavor]

1 hour ago, watchweasol said:

Hi  Esslinger web site gives a good insight to the fitting and measuring of crystals in the from of a tutorial. well worth a look before going any further.

Thank you very much, useful information I've done other types of crystals, but never this type therefor, with no room for error, better double check and I've learned already some do's & don'ts.

Below 2 pictures of the watch-case, without and with tachymeter-ring. The tachymeter sits in a housing-ring with an ID of 29.96mm. Above the tachymeter-ring sits a slightly wider housing-ring with an ID of 29.98mm and measured from the top of the case that ring sits 1.2mm deep. However the width of the 29.98 ring is, best guesstimate, 0.8mm.

Most likely the crystal bottoms out on top of the tachymeter-ring.

 

I therefore assume that the crystal-gasket required has to have an diameter of ø30 mm and a height of 0.8mm.

CousinsUK has two 0.8mm heigh gaskets for 1mm crystals on offer, an ISO Swiss;

and a Sternkreuz, also 0.8mm heigh.

According to the Esslinger information, one needs to first order the crystal-gasket, install & measure it and thereafter order the right size crystal ...... (?)

Given the fact that CousinsUK gives the ID, can one not order the crystal as well?

The ISO Swiss has an ID of 29.28mm and the Sternkreuz has an ID of 29.3mm

The 1mm thick CousinsUK (sapphire) crystals on offer come with 0.1mm increments. The appropriate range would be 29.2 / 29.3 or 29.4 mm.

Would the 29.3mm crystal with the Sternkreuz 30x29.3x0.8mm gasket be my best bet ?

Any thoughts / comments on my "logic" ..... ?

 

 

 

 

 

 

 

Edited October 27, 2019 by Endeavor

[watchweasol]

Hi  I understand where you are coming from, but I would follow the Esslinger advice that way having fitted the gasket to the case you then measure again for the crystal that way there is less margin for error and better chance of a perfect fit.

[Endeavor]

13 minutes ago, watchweasol said:

Hi  I understand where you are coming from, but I would follow the Esslinger advice that way having fitted the gasket to the case you then measure again for the crystal that way there is less margin for error and better chance of a perfect fit.

After fitting the gasket and the measurement is, say for argument sake, 29.25mm, do you than order the 29.2 or the 29.3mm crystal?

[watchweasol]

According to convension what ever the measurement is add 0.01, I believe that's what is quoted by Esslinger and others. The criteria is that when fitting the crystal it must be pressed in square to avoid a pinched gasket. So great care must be taken on fitting. A screw press is best as it is more controllable. I have done it using the hand press I lubricates the crystal edges a little water, just a wipe, lay the crystal on to the gasket ensure its square and press gently so it eases it in with little or no real force, also choose the correct dies for the job.

[Endeavor]

7 hours ago, watchweasol said:

According to convension what ever the measurement is add 0.01, I believe that's what is quoted by Esslinger and others. The criteria is that when fitting the crystal it must be pressed in square to avoid a pinched gasket. So great care must be taken on fitting. A screw press is best as it is more controllable. I have done it using the hand press I lubricates the crystal edges a little water, just a wipe, lay the crystal on to the gasket ensure its square and press gently so it eases it in with little or no real force, also choose the correct dies for the job.

There are many tools we all wish to have but I, just like you, have to do it with a hand press and from the limited set of dies, the closest fitting   The good news is however, that CousinsUK warehouse seems to be filled to the brim with crystal-gaskets & crystals, so that takes the "only-one-shot"-pressure a bit off.

It's nice to note that you talk out of experience and your answers & tips are clear enough for me. Thanks a lot for your help !

Edited October 28, 2019 by Endeavor

[watchweasol]

My pleasure glad to be of constructive help.

[StuartBaker104]

I have a screw press from China which wasn’t very expensive (45gbp from Redrooster) and learnt (as you have) that they should be used to both remove and fit mineral glasses.  As long as they aren’t damaged then the crystal gaskets can be re used.

[Endeavor]

9 hours ago, StuartBaker104 said:

I have a screw press from China which wasn’t very expensive (45gbp from Redrooster) and learnt (as you have) that they should be used to both remove and fit mineral glasses.  As long as they aren’t damaged then the crystal gaskets can be re used.

Thank you for the tip

The new watch case has arrived and I pressed (with my old hand-press & correct die) the glass crystal out without any issue or damage to the crystal nor gasket. The glass crystal measures 29.4mm. The gasket is a bit harder to measure (even when seated in the housing) due its size, shape and my normal size sliding-caliper.

What I have learned however is that there are two different types of crystal-gaskets; the "L" shape and the "I" shape. The "L" shape has a shape, as the letter suggest, of a cylindrical top part and at the bottom a thin "ring" with a smaller diameter, forming a kind of "stop" on which the crystal bottoms out. One can not press the crystal through a "L"-gasket whereas with an "I" shape gasket you can. The "I"shape is basically just one flush cylinder.

As you can see above, both CousinsUK pictures of the gasket which I had initially chosen have the "I" shape, marked as: "x0.80 I Gasket" and "I Gasket 30.0"

The 1mm high gasket which came out the new housing has a "L" shape and is, as far as I can see, in that size not available by CousinsUK. The bulk of gaskets available do have the "I" shape.

Even though mineral glass crystal which came out of the new housing is totally perfect, I opted to order a 29.4x1mm sapphire crystal and it will be set in the "old" "L" shape gasket ..... at least that's the plan

BTW; these sapphire crystals are IMHO very cheap, only £8.95 .

Kind regards ....

Edited October 31, 2019 by Endeavor

[Endeavor]

Just to report back; Ordered a sapphire 29.4mm crystal and pressed it (with my hand-press), using the gasket out of the new case, into the numbered case without any issue.

The movement has been fully repaired & restored, dynamic poising of the balance and the case is now complete, original and in very nice condition. According to all the information I can find of the 104x Poljot "Mir"s made (number of individuals who visited the MIR during its lifespan between 1986 - 2001), this the 3rd known (the other two known cases are 035-104 & 070-104). It has never been featured in any catalogue.

I'm pleased with the results and thanks for the help

[dadistic]

Wow.

An outstanding restoration of a valuable piece of history, congrats.

 

 

[Endeavor]

Thank you

A piece of history, just like with any watches out of the Soviet Union (CCCP), which never comes back. Sadly the MIR has been "burned" due to the collapse of the Soviet Union, further funding's and age. It was a "trail-blazer" for the current ISS. The "Buran" space-shuttle was another. I'm honored to own a watch which commemorates such an exceptional moment in time !

In a few days time I'll be updating & concluding the whole story of this MIR watch on the WUS-forum: https://forums.watchuseek.com/f10/poljot-3133-commemorating-mir-space-station-5055311.html

[Endeavor]

https://forums.watchuseek.com/f10/poljot-3133-commemorating-mir-space-station-5055311-3.html#post50264399