Exploding Crystal and Watch Gasket Woes

The goal is to determine the correct size for the crystal and watch gasket for the 3D printed stainless steel watch body. But I was having problems with the crystal exploding!
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[@FranklyPeetoons]

Your videos conquer the problems encountered in other such videos - you effectively depict milling WHILE cooling/lubricant is spraying, without obfuscating the work. And the difficulties with clamping while machining provide a revealing glimpse into unintended consequences. Top-notch problem-solving and documentation.

[@dass1333]

Everything I make does not need much for tolerances, it's art. But I like to work on skill and best practices. Your efforts to get perfection helps inspire better methods. If one accepts adequate they have stalled. Getting a new to me X Y today so my mill can make more precise mistakes. Good work John. Thanks for the thought path to discovery.

[@BaconbuttywithCheese]

My intuition tells me the pocket for the crystal needs a cleanup pass with a rotary tool ie boring bar to give a non cnc finish. At the micro scale it will have a lot of irregularities which would not be there if a lathe was used for example. My 0.02.

[@universebecomingltd]

Nope, I didn't catch that either; however, when you revealed the problem, I then remembered having similar problems with vices. I didn't think of it because I haven't done any machining in around eight years. As a side note, a channel improvement might be to provide a few more sentences of background for what you're working on, for those new to the channel. I'm not new to the channel, but I don't have time to catch all of the videos you publish. I knew you were designing a wrist watch, but I was puzzled by why this experiment appeared to be too large compared to the watch bezels I've seen you make I love your videos! You are highly meticulous, and that makes your videos highly entertaining to me.

[@JohnSL]

That's a great suggestion, thank you.

[@DonkeyHotie]

You should download and spend some quality time reading the Parker O ring catalog. They freely share all their engineering and research data that goes into each type of O ring joint (end compression, side compression, sliding, static, etc). There is a specific type of joint you're designing there. It has design guidelines for how much compression you want in the material, for the best performance, in explicitly that type of application. TL;DR: you want about 10% compression designed into the material when it's installed. Some more, some less but, that'll get you close.

[@JohnSL]

Been there, done that. I used that information for the o-rings. But I have not been able to find information about the Hytrel gaskets.

[@Preso58]

So, it's true what Robin Renzetti says, everything is made of rubber!

[@christiansrensen3810]

I did have similar problem, so when I saw that you clamped, I thought maybe you calculated this and the ring seals would take the deformation.... but when I saw the first test with bulbles, I thought this my rabbit hole. 😂 The clamp you have is very good...don't underest the power of this.. ..

[@thoughtbombdesign]

I didn't see it either. I was thinking surface finish on a sealing surface. If you ever do have that issue, you can cut the sealing surface with something like a fly cutter so the machining marks are concentric instead of crossing the sealing face. That is ideal. My other guess was that what you screw the back of the fixture on you were actually building pressure 'inside the watch' and pushing the crystal out. If course it was much more basic.... 🙄🤣

[@techkits]

I love your attention to detail and your troubleshooting skills! I wonder if these parts be better suited for making on a lathe?

[@JohnSL]

I'm guessing they could be. But I don't have a CNC lathe. Plus, the wall finish that matters, which is the "vertical" wall, will have a much better finish from an end mill than from a lathe. And that's the wall that provides the seal with the gasket (it's between the outside diameter of the crystal and the body).

[@herro-wo3sg]

Put a polishing bob in a collet holder and put some mold polish in the o ring groove and circle interpolate the o ring groove with the polishing bob. You should only have to go about .01 deep to press hard enough and you'll want to run your spindle as fast as it can go and use a slow feed rate, that should give a really nice surface for an o ring seal without having to use a lathe.

[@DominikKomzik]

my first guess was leak at point of lead-in/out of roughing or finishing path raised small burr but when it came loose i was clueless

[@JohnSL]

That was my first guess as well...

[@PaulSteMarie]

I can't really guess, since you told me the issue, but i think i would have thought it was a flaw in the o-ring, especially since it looked like the bubbles were coming from a single location. Had they been visible at two locations 180°apart, perhaps i would have realized what was happening.

[@David_11111]

yay

[@dass1333]

Should be. What could go wrong.

[@David_11111]

no lube ?

[@JohnSL]

My understanding is that for testing, it's best not to use something as that's more demanding. For final assembly, yes, add lube, as this will help with water resistance.

[@David_11111]

might help with seal, have tested a few dive watches. same kit or very similar !

[@briansaban3849]

Hey John, Did you happen to get my email? Maybe in your spam