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[dpn]

Hello all,

I've joined this forum to learn more about how to cut watch dials out of semiprecious and exotic materials.

Watch dials have very precise dimensional requirements -- one movement, for instance, requires a dial that's 36.4mm in diameter and 0.4mm. Depending on the movement, there are also quite a few precise holes that need to be drilled to accommodate hands, dial feet, hour markers, etc.

I'm a complete newbie, and I really have no idea how these sorts of cuts are accomplished. It's generally known that these sorts of dials have a very high manufacturing failure rate, with materials like opal being especially difficult to work with.

Assuming that one could get a round blank of the correct diameter, would a lapidary slab cutting saw be able to create slices as thin as 0.4mm? I'm also thinking that it might be possible to make very thin (~1.0mm) cuts with a slab saw and then sand the material down to a correct uniform flatness and thickness using a lapping machine?

I'm really starting from zero in terms of lapidary skills, and appreciate that there will be a steep learning curve with a lot of practice required.

If anyone is curious, I've attached a few photographs of very high end watches that feature semiprecious stone dials. I know that it's *possible* for large watch companies to endure high failure rates and create these dials, but I don't know whether it's *feasible* for a hobbyist or small-scale maker like me to get these sorts of results without spending tens of thousands of dollars on tools.

Any advice is appreciated!

Cheers,

Dan

A variety of semiprecious stone dials ...


Malachite


Opal


Turqoise


Lapis

[Slabbercabber]

Piaget uses a dedicated CNC machine that literally cost well over $100,000 to build.  Doing the work by hand is theoretically possible and they most likely did a few that way first to check the feasibility.  Getting the precision required for a watch using standard lapidary tools would be an enormous challenge.  It will be interesting following your experience with this.  I wish you the best of luck and I have no doubt you will get a lot of help from the people here.  As far as a round blank, you will need to start with a core drill as close to final size as possible and then turn it to exact dimension using a lathe.  Then drill the core while still in the lathe.  Notice that Piaget does not include markers on these watches.  Getting the holes in the exact location would be another huge challenge.  One good thing about starting with a round core is that you can polish the face before slicing.  Slicing to .04mm will be the real test.  I just don't have a clue how you are going to do that.

[R.U. Sirius]

I've done a bit of research a while back, but never tried pursuing this in practice. I'll share some opinions you could take with a grain of salt.

First off, the dial thickness "requirements" are not really requirements, but simply a historical consequence of the dials traditionally being made from sheet metal. You could accommodate thicker dials, but would need to design the case accordingly. There is plenty of room - the plastic "movement holders" we see in quartz watches are required to fill up the unused space, including thickness, between the case back and the movement. Some watches also have spacer rings between the movement and the dial!

Yes, the hands might need to be custom made with extension tubes that fit the movement posts.

Next, the stones. Note the distinction between the hardness and toughness when researching them. Some agates or jade might be tough enough and defect-free to stand on their own, although some destructive testing of a significant number of samples would be required to comfortably include these in something you'd sell. Otherwise, the turquoise, malachite, opal, or lapis examples you pointed to are certainly epoxied to a backing support (or have an epoxy backing) and then thinned down by sanding. I suspect that turquoise may even be not the real stone but "reconstituted turquoise" (look it up). You can learn a lot by reading up on how opal doublets are made, in this forum and elsewhere.

Come back and tell us what you found out!

[lithicbeads]

 You can simply lap the slab down to size as done with thin sections. When lapping things this thin it will be evident that the " uphill " side of the stone cuts faster than the trailing edge. This is fairly easily solved by using an old faceting machine to lap the slab. You can set the quill on the vertical setting and spin the dopped slab to get acceptable tolerances.

[freeformcabs]

I've had success in slabbing rough down to 1.5-2mm. Using a plaster mixture to incase several pieces of rough. But never any thinner. Its worth trying again but on a smaller saw with a thinner blade.

[Felicia]

There are small trim saws designed for finest work in faceting, using thin blades. I would say cut, smooth both faces to a fairly fine sand, and as r. u. Sirius mentioned epoxy to a backing before working to final thinness. One more thing, how are these faces attached, are they, say, epoxied to a metal backing? You might need to epoxy to that and do the final sand and polish from there. This sounds like a fascinating project, never done it myself, just trying to think of what might be done in a hobby setting. Enjoy your new endeavor!

[R.U. Sirius]

Just to add - there was an interesting post about slicing opals using in-house built wire saw.

Perhaps we shouldn't get too obsessed with thin blades here, though: your goal is to slice precisely. Thicker blades are actually more stable than thin ones. It's just that thick blades will waste more material. I would say a well aligned and vibration-free blade and vise are more important here, as well as choosing your rough. Stabilizing the slab (look it up) might also be wise for certain materials.

[dpn]

Thanks all for the wealth of information and the warm welcome to the forum! You all have provided me with great starting points for my research.

I'm not interested in creating custom cases and crystals, but using commodity parts. I may be more height restricted going this route than I would be with a bespoke case & crystal, but there are some nice commodity high-domed crystals that might give me more room to work. The note about hand extenders is a great one, however, as it'll probably be easier to get to a 1.0mm height with a dial than an 0.4mm height.

I agree that hour markers, etc. will be infeasible due to the precision required. A better solution would be adding a chapter ring, as Tag Heuer did with this fordite watch:



I've done more research since my original post, and I absolutely agree with @R.U. Sirius's suggestion to look into opal doublets and triplets -- a very thin opal doublet is probably a very good model of how to accomplish this.

To this point, does anyone know how thinly opals are sliced for doublets and triplets? I'm guessing that the answer is *really* thin, and the tools and techniques necessary to accomplish that are probably the right track for me to pursue for my project. I know that opal doublets and triplets aren't exactly embraced as good things, but I'm quite curious about the techniques necessary to create them. I'll be Googling this, but wouldn't object if anyone knew this information offhand. ;-)

Shoot, with a thin enough slice, it'd be trivial to mount my "stone" to a blank brass dial and take advantage of the brass dial's feet, etc.

As far as tools, I'm going to be looking into slabbing saws and lapping machines to start. As a total newbie, I know very, very little about these. My instinct is that it'd be easiest to get a nice thin slice with a larger diameter (12"?) thin-bladed slabbing saw. There's a local lapidary club I might look into to see about learning how to use this equipment. My instinct might be totally off, though, is this the sort of application that a smaller diameter slabbing saw might be better at? I feel like the cutting ability of the saw will be less important than how precisely it can be used -- forgive my lack of terminology, but having a precise way to smoothly and evenly feed the material to the saw sounds more important than the saw's raw power. Getting a "thin enough" slice to feed to a lapping machine to work down to the final height seems like a better option than trying to hit the 0.4mm slice target using only a slabbing saw.

And for the actual dial materials -- I'm honestly more interested in experimenting with weird but inexpensive stuff than expensive and difficult materials like opal. The idea of a fordite, "surfite", or "bowlerite" dial is what is really driving me here -- I'm absolutely in love with the fordite dials on those Tag Heuer watches. Not only are these synthetic materials inexpensive and cool, but they appear to be fairly easy to work with. See, e.g., this desktop CNC mill shaping fordite. Fordite has specifically been compared to rhodochrosite  -- 3.5-4 hardness, but brittle. The techniques required, however, seem squarely in the realm of the lapidary. And I certainly wouldn't say no to an opal or lapis dialed watch, if I figured out the technique!

Anyway, thank you all for the warm welcome and great information! I've got a lot more research to do. I'll keep updating this thread as a I figure stuff out, both to track my progress and to help other folks out if they're researching a similar idea. I'm a huge believer in open source information.

Cheers,

Dan

[R.U. Sirius]

I would likely try the following process flow, and am curious what others think:

• Cut or procure thin slabs and select fracture-free areas. Trim close to (but slightly larger) than the dial diameter. If possible, avoid oil saws and work with water-based coolants only, to ensure better adhesive bond later on
• Procure a blank dial and grind/lap to thin it down, checking the uniformity carefully
• Mount the stone preform to the dial using an appropriate epoxy that bonds to brass and stone. To minimize the risk of delamination due to thermal stress (brass and stone have different coefficients of thermal expansion), choose an epoxy that is slightly flexible. Also, choose an epoxy that will cure at a relatively low temperature (80C-95C). Clamp and cure. Let the bond develop over a few days.
• Drill the center hole in the stone using a diamond burr, through the existing hole in the brass. You might want to first temporarily mount the stack onto a support layer of marble or glass using wax.(
• Grind the perimeter of the stone to the dial. Use the finest grit that will still do the job, to avoid chipping. I believe this doesn't require perfection, as the perimeter of the dial will be hidden in the end.
• Grind the stone down to the desired thickness on a flat lap, checking frequently.
• Polish the stone

[dpn]

I love it, R.U. Sirius. Thank you so much for brainstorming this with me!

I'm also very eager to hear what other folks might suggest.

[lithicbeads]

Traditionally waterglass was used to glue the thin slab to a strong backing for lapping then soak it off with water.

[dpn]

Thank you @lithicbeads for this info! It gives me some specifics to research and investigate it. As a complete newbie, even learning the vocabulary of basic techniques and tool names is a challenge.


Sent from my iPhone using Tapatalk

[dpn]

As an update, just in case anyone is curious:

1) I have access to a Buehler "IsoMet Low Speed Precision Cutter" through an archaeologist friend who uses it to cut very thin, very precise slices of bone and teeth for examination through a compound microscope for his osteology research. (All I can say here is that it's cool to be a weirdo with weird friends.)

2) I'm still planning on joining my local lapidary club, the Sacramento Mineral Society, to make some connections, get some in-person tips, and make use of their workshop equipment. This is how I hope to cut my rough material into something suitable for turning and shaping on a lathe.

3) I'm still researching lathes, lapping machines, and how to best use them to create dial-size cylinders for cutting on the Buehler precision cutter, which would then be further flatted and thinned down on a lapping machine.

4) As I've researching things more, the final "stone" dial + backing template thickness may be less of an issue than I had feared. There are hand extenders available to provide more vertical clearance above the dials for a variety of movements, and it's possible to find higher-domed sapphire crystals that will also increase my vertical clearance.

///

Anyway, my efforts here are very much alive. I hope, with the advice of this forum and my local lapidary club, to get some additional advice and tips as I'm ready to progress into proof of concept and prototyping. Because I have really benefited from open-source information and the help of others over the years, I intend to continue documenting my efforts in a public way so other other folks might benefit as well.

Thanks again, everyone, for the warm welcome and great tips! I have donated to this forum as a tangible way of saying thank you.

-- Dan

[Felicia]

The right equipment can show up in unexpected places. That sounds like it should cover the bases as far as cutting the material goes, and definitely minimize finishing work. Like to know how it works out!

[Craigab]

Hi Dan,
You may want to get in touch with me. I have a little inside knowledge on this exact subject.  I'd be happy to tell you what I know. 
Craig