Making a custom crystal

I recently had a need to create a custom crystal for a watch I have in the shop. So I thought I'd share what was involved. This is a rectangular crystal that has an arc in one direction, and the crystal that was on the watch was cracked, and one side had some material missing. I tried to find a replacement of the right size with no luck - I even looked for something oversized that I could cut down, but no luck.

So I ordered in some acrylic material, and decided to make it myself. I first traced out the profile from the case, not the existing crystal, as that crystal wasn't an exact fit in terms of the curve in it:



Selected some cedar that was wide enough, and transferred the profile over:



Cut the profile out on the scroll saw:





Had to fine tune it by hand to make is as close as possible:





Cut the crystal stock:



Now getting ready to heat:



Into the oven - had to play around with the temperatures:



Once it had formed, the form is removed and left to come fully to room temperature:







Close:



I ended up making a few to get it just right. Once I had one that looked good, the cutting and fitting started:





Not bad:



The watch this is for is a Tiffany dialed Patek Philippe, so of course the movement was serviced:



Final assembly time:



The profile looks pretty good:





Overall, I am pretty satisfied with this result:



Learned a few things along the way, the first is to go slow when trimming, because it's very easy to go too far...🤦

Another was about temperatures. Getting impatient and overshooting the required temperatures is not a good idea. It made the acrylic too plastic, and it picked up defects that could not be polished out. I found that 138 C or about 280 F is just right for this.

I was fortunate that this only had an arc in one direction, or this would have been much more complex to make.

Cheers, Al

That's bad ass.

I probably had a glass one that would fit.

Yes, that's how these are fitted. I use UV curing cement for this.

That looks great! Your client is going to be thrilled.

This is the polar opposite of "servicing" practices of many watch companies described in this thread (starts about midway down the second page): https://omegaforums.net/threads/has-the-modern-watch-scene-lost-a-bit-of-spark-lately.130380/

This sort of craft work is inspiring! Nice work Al!

This is cool! Is this acrylic material specific for making replacement watch crystals, or is it a typical acrylic sheet like you can pick up at a hardware store?

Possibly, but the chances of you having one of the correct dimensions, and more importantly the correct curve to fit this case (because it would have to be perfect) from a random selection of crystals, I would suggest I’d have better luck winning the lottery.

Thanks for sharing this! Nice watch and the owner must be thrilled. 👍

Is it waterproof now? 😗

Since this is only curved in one direction, this sort of completely just isn’t needed. It would actually add a fair bit of work to polish it, where this material really only needed polishing to remove incidental scratches.

Cheers, Al

As waterproof as it ever was! 😉

It’s not a specific material for watch crystals.

My crystal cabinets with approximately 30,000 NOS glass crystals are hardly random. But that’s okay!