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Unobtainium replacement acrylic crystal -1960's Dugena ladies automatic


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Hello to everyone

The unimaginable has happened.

I have a ladies Dugena automatic on the bench, from what I can make out a model 3343 with the ETA 2651 movement with date complication.

The original acrylic crystal was cracked and had allowed moisture onto the dial. I began looking for a replacement.

No joy from local suppliers.

I began contacting local watchmakers, some of whom have been around a long time. One seemed confident, and asked for a sample. Foolishly, I sent him the original cracked piece as a sample, and he promptly sent me a replacement...which was the incorrect part....and didn't return the sample.

I asked for it, and he told me he had thrown it away, so confident was he that he had sent the correct replacement. Turned out he had merely contacted a local supplier, one of the same suppliers I had earlier been in touch with, and they had sent him something which he hadn't even checked before forwarding it on to me.

So I sit, with a beautifully running movement (a service and a new mainspring and away she went like a real champ!), ....and no crystal. I emailed the factory in Germany and....nope, nothing, not even a drawing or dimensional data available.

Much pondering and measuring revealed that a CNC milled replacement wouldn't work because it does not have a flat bottom ( and a simple flat bottomed crystal would not allow space for the hands and their posts) and then there's the finish from CNC milling to deal with. 3D printing has the striations of the layers, and resin printing has the same but not as pronounced.

It's a family heirloom, not mine, and once I have finished with it it is going to the great grandaughter of the original owner.....so yes, I'm in a pickle.

So my first question is.....how are crystals measured and labelled and named?

I see FB-FE-FH-FO-FR-FT etc etc....then I see lots of measurements....none of which I am too familiar with.

The part I need would be round with a part projecting from the housing or flange, itself concentrically circular with the flange but with two flats one at 12 o clock and one at 6 o clock, just like the middle one pictured towards the top of this page...https://www.flume.de/en/watch-glasses-watches-watches-plastic-special-fb-fe-fh-fo-fr-ft.html?next_page=1#NAVIGATION&listResult=&order=2&direction=asc#NAVIGATION

The flange itself would need to be 229, the distance across the flats 192 and the diameter of the raised circular part 204.

How are crystals catalogued and by what nomeclature?

Is there a resource somewhere that tells the story of how they are measured and described?

On to the second question - has anyone here had experience with casting unobtainium replacement crystals using water-clear polyurethane resin in a silicone rubber mould? Because that's what I am about to embark on doing.

I figure on having three pieces of acrylic lasercut at the local signage shop - a top, a single-piece that makes up the 'sidewalls', and a flange. Then thinly bonding them together with a drop or two of cyanoacrylate, and using this as a plug from which to make a silicone mould. Then I will cast a new crystal into that mould using low viscosity, vacuum-degassed clear UV stabilised polyurethane resin. I plan to make 2 or 3 so the owner has some spares for the future.

Anyone here with thoughts or experiences to share? It would be much appreciated....

20201219_172542.thumb.jpg.23e83c8ef2fc43a0e612041b0242fee2.jpg

There's the original on the left next to the (tatty) dial.

20210222_170306.thumb.jpg.0baec7f56073a549ec0da4970164cff2.jpg

One of the three or four incorrect ones I have been supplied with - close but far from worth a fag-end, never mind a cigar.

20210218_091420.thumb.jpg.5ba7213e70b28ce4c59edc37c13af586.jpg

That's the shape of what I am looking for....

Shame - look at that dial!

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Spend some time in the Sternkreuz catalogue and the G-S catalogue. They are big pdf files available online. It takes some time to really figure those catalogues out. If you don't find what you are exactly looking for, you can often modify something they do have, or glue it in to fit.

I think they will make custom items, I don't think it's cheap.

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So the 'F' is 'formproof' ... the flange-with-a-raised-shape you describe. The shape then being rectangular, bale, elliptical etc. hence FR, FB, FE.

Your need description is of the FE range from Sternkreuz. Sternkreuz's own website is a bit clunky but Cousins comes to the rescue with: https://www.cousinsuk.com/PDF/products/4709_FE205418_R19Smaller.pdf

The bit I'm not getting though is if I zoom in on your parts tray, that old crystal looks round as does the case aperture. Certainly nothing like the extreme of the crystal you're holding or the 229x192 you mention. Optical illusion or a misunderstanding of your measurements?

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I just discovered these guys the other day.  They may solve your problem

 

"Twin City Supply is one of the few remaining material houses to actually cut & fit crystals. In addition, we are one of the largest suppliers of G&S, BB, Perfit, Sternkruz, Security Brand, Seiko, Citizen, Bulova, Pulsar, & Mineral Glass Crystals in the world. Our inventory is actually larger than some manufacturers! Let our experience help you! Check out 6 additional pages of special order, & in stock Security brand crystals in our Current PDF ads & Information section!"

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21 hours ago, KOwatch said:

Spend some time in the Sternkreuz catalogue and the G-S catalogue. They are big pdf files available online. It takes some time to really figure those catalogues out. If you don't find what you are exactly looking for, you can often modify something they do have, or glue it in to fit.

I think they will make custom items, I don't think it's cheap.

Thanks KOwatch - i have seen the Sternkreuz name before, I didn't know they had a catalogue available. I couldn't find it in the GS catalogue but there's also no harm in spending a while having another look before putting all that time into making something.

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14 hours ago, WatchMaker said:

So the 'F' is 'formproof' ... the flange-with-a-raised-shape you describe. The shape then being rectangular, bale, elliptical etc. hence FR, FB, FE.

Your need description is of the FE range from Sternkreuz. Sternkreuz's own website is a bit clunky but Cousins comes to the rescue with: https://www.cousinsuk.com/PDF/products/4709_FE205418_R19Smaller.pdf

The bit I'm not getting though is if I zoom in on your parts tray, that old crystal looks round as does the case aperture. Certainly nothing like the extreme of the crystal you're holding or the 229x192 you mention. Optical illusion or a misunderstanding of your measurements?

Thanks Watchmaker, I saw somewhere that this would be a barrell shape, IIRC.

Thanks for the explanation.

No optical illusion - just a very bad image. Here's a better one......

 

20210119_144740(1).jpg

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14 hours ago, LittleWatchShop said:

I just discovered these guys the other day.  They may solve your problem

 

"Twin City Supply is one of the few remaining material houses to actually cut & fit crystals. In addition, we are one of the largest suppliers of G&S, BB, Perfit, Sternkruz, Security Brand, Seiko, Citizen, Bulova, Pulsar, & Mineral Glass Crystals in the world. Our inventory is actually larger than some manufacturers! Let our experience help you! Check out 6 additional pages of special order, & in stock Security brand crystals in our Current PDF ads & Information section!"

Thanks for the link - I will check it out. How's things in Texas?...one of my favourite states though far from here in South Africa. I've always enjoyed visiting there.....everyone is so polite! Maybe because almost everyone is packing....;-)

Stay warm!

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1 hour ago, Geoffrey said:

almost everyone is packing

Yeah...pretty much, although there are a few seeping into the state with alternative views.  Arg!

We are known for our friendliness...especially in the rural areas.  In the city, maybe less, but still pretty congenial.  I live in the rural part of central Texas.  You have a flat...somebody will stop and fix it for you.

Let me know how it goes with Twin City...from their website, they seem like a real Godsend for crystal needs.

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2 hours ago, Geoffrey said:

I saw somewhere that this would be a barrell shape

I've found you a page from Sternkreuz as below explaining the shapes. I'd say you've been going down the wrong route if you're pursuing FT (=barrel). I said FE above because from your initial pictures and explanation things looks more elliptical.

BUT out of interest I took a copy of the now clearer aerial view of your case and superimposed a perfect circle on it...

image.png.5e5394791e3c0147e3d3f4f1e810d034.png

And this does seem to be a circular aperture apart from those slightly flattened 12 and 6 o'clock positions. But nothing extreme on the face of it.

I know you've been pursuing a flanged crystal as presumably that's how it came originally but if this is elusive how about just experimenting with a much more widely available high dome crystal. You'd have to browse the Sternkreuz catalogue to see what you think is best but, for instance, if you went for an HW or HH range (high dome or extreme high dome) crystal and gently sanded away enough material at those flattened positions you should get the shape you need. The high wall aspect of the crystal wouldn't then be used to extend above the case but to go into the case against its sidewalls to locate it. Standard round domed crystals are widely available and inexpensive.

This is just an idea of course!

image.png.4e990b0bb9ab1a747dab408a91b5d318.png

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Looks to me as if it might be the FT category. That is if the bottom of the crystal is round and the top has the two flats.

My friend has the same type of situation with a Barthelay brand ladies watch, but it is round bottom, oval top. Tough get. Good luck.

 

 

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On 2/24/2021 at 6:58 PM, Nucejoe said:

So based on cousins catalogue which one do you need? 

Sorry to take a while to respond and thank you, Nucejoe. I've been single parenting a very active 11-month old ( a future apprentice, perhaps?) for a few days, but back to normal now.

I appreciate the link to the cousins catalogue from WatchMaker.

Unfortunately, I don't see what I need there. I'm looking for a flange diameter of 229, 195 across the flats and something like 204 diameter across the circular part. Unfortunately as I say, I don't see anything like that on the Cousins page. How wonderful it would be to have found it, and worth doing the tedious process of importing into South Africa.

 

I appreciate the lead though, guys!

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On 2/26/2021 at 6:23 PM, MrRoundel said:

Looks to me as if it might be the FT category. That is if the bottom of the crystal is round and the top has the two flats.

My friend has the same type of situation with a Barthelay brand ladies watch, but it is round bottom, oval top. Tough get. Good luck.

 

 

MrRoundel,  the 12 o clock and 6 o clock positions have quite noticeable flats. I think it's in the FT category, tonnenform or barrel shaped. I imagine a side-on view of a wooden barrel - flat at the top on bottom and curved to a greater or lesser extent on the sides.

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