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What Material and Technique for Indicator Crystals?

Making your own bezel and the hot chip problem suggests that glass crystals may be a better choice.

But then, to make the idea complete, you would need a 3D printing stock that both melted in the printer and did not melt with the hot chips. Or, since this is a metal shop forum, just make the bezel from metal. Aluminum and brass come to mind. There's a nice challenge to your shop skills.

Another idea for a heat proof bezel would be to 3D print one and use it as the pattern for a mold. Then pour a heat resistant plastic or silicone material or even a metal like aluminum in the mold for the final bezel.

Since you want to make everything yourself, there are many possibilities.

Aside: They make all kinds of 3D print filaments. I wonder if they will ever come up with an optically clear one and a way to print with it with optically flat surfaces. I know; I dream. But what the heck, in my life I have seen TV cameras come down from the size AND WEIGHT of a refrigerator to small enough for my cell phone to have four of them in it and they aren't even the main components of the cell PHONE. And then there's computers: all I can say is wow. Dreams do come true. And I sit here typing this on one such dream.



One other alternative that is simple but not nearly as elegant as removing the bezel and forming a crystal as was thoroughly lined out by Jim Rozen in earlier posts to this thread, is to simply 3-D print a snap-on bezel to hold an acrylic or polycarbonate replacement or add-on crystal. I did printed one first for an inexpensive pressure gage that gets banged around. That worked so well that I made a couple of add-ons for indicators that often have hot chips fall on them melting into the crystal. With the add-on crystal, I'll just pop off the plastic bezel, put on another acrylic crystal cover, and be back in business in no time. This is not a fix that most would want for the Interapids and such. But it is quick and dirty and actually add a little protective bumper (that could get in the way) to the gage.

Brief video of printed bezel


It took about 5 minutes to CAD draw the file for this bezel. It is parametric so that its diameter takes just a click to change. Printing took about 20 mins. Material cost is pennies.
View attachment 384225
These cheapo indicators see hard duty in my shop. A little extra bumper and a sacrificial crystal is a plus.
View attachment 384226

These bezels were printed in PLA which is pretty durable stuff. As is they are very stiff and would be difficult to collapse a strong grip I could also have printed them in PETG which is even more robust but PLA was already in the printer.

Denis
 
Aside: They make all kinds of 3D print filaments. I wonder if they will ever come up with an optically clear one and a way to print with it with optically flat surfaces. I know; I dream.
You mean like this:
1674048833525.png
I am cheating here a bit as these are resin (SLA) prints. But they are 3-D printed using a resin I could buy (pricey) and load into my resin printer. I would guess print time for a "cystal" 1.5" diameter and .062" thick might be about 7 minutes. CAD drawing time would be 5 mins. That is less time than it would take for me to find a chunk of suitable single-weight glass let alone set up an abrasive slurry and cut a piece of tubing to use in my mill as a cutter.

"Or, since this is a metal shop forum, just make the bezel from metal. Aluminum and brass come to mind. There's a nice challenge to your shop skills."
I have made, in the past, both glass cystals cut with slurry abrasive and made steel and aluminum bezels which I think are pretty easy whether cutting them from bar stock or faceplate turning. But, since we are talking about 3-D printing, why not just 3-D print the bezel from aluminum or stainless or better titanium. Metal printing is slower than plastic printing, but if Elon Musk can 3-D print his entire rocket motors, I suppose we should be able to make a bezel.

I agree with you observation concerning tech advances we have seen. I often remind my grand kids that Dick Tracy's comic-book wrist radio was an improbable futuristic fairy tale when I was young and using slide rules and rotary-dial wall telephones.

Denis
 
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You mean like this:
View attachment 384351
I am cheating here a bit as these are resin (SLA) prints. But they are 3-D printed using a resin I could buy (pricey) and load into my resin printer. I would guess print time for a "cystal" 1.5" diameter and .062" thick might be about 7 minutes. CAD drawing time would be 5 mins. That is less time than it would take for me to find a chunk of suitable single-weight glass let alone set up an abrasive slurry and cut a piece of tubing to use in my mill as a cutter.

"Or, since this is a metal shop forum, just make the bezel from metal. Aluminum and brass come to mind. There's a nice challenge to your shop skills."
I have made, in the past, both glass cystals cut with slurry abrasive and made steel and aluminum bezels which I think are pretty easy whether cutting them from bar stock or faceplate turning. But, since we are talking about 3-D printing, why not just 3-D print the bezel from aluminum or stainless or better titanium. Metal printing is slower than plastic printing, but if Elon Musk can 3-D print his entire rocket motors, I suppose we should be able to make a bezel.

I agree with you observation concerning tech advances we have seen. I often remind my grand kids that Dick Tracy's comic-book wrist radio was an improbable futuristic fairy tale when I was young and using slide rules and rotary-dial wall telephones.

Denis
 
Watch crystals are available in the UK for around £1.50, flat, domed, high domed. Usually in 0.1mm increments in diameter.
I need to get one for a Compac DTI where for some reason the original has shrunk and fallen out. Who would try and make one at this price?
 
Watch crystals are available in the UK for around £1.50, flat, domed, high domed. Usually in 0.1mm increments in diameter.
I need to get one for a Compac DTI where for some reason the original has shrunk and fallen out. Who would try and make one at this price?
Me, even if the crystals were free—-if I were putting my Compac where hot scarf might fall on it. (I don’t) I’d just print an “auxiliary bezel“ as above and use it to clip on a glass sacrificial bezel. It’s a lot easier to use a sacrificial crystal than it is to replace an OEM crystal.
:-)

Denis

And I have feeling Rozen enjoys using his perfected technique so much that he’d be making his own regardless.
 








 
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