Using polyester casting resin for AV-bay windows?

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Jul 22, 2015
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I am putting a window in the AV-bay for my level three, and was looking at ways to make the transparent bit.

ImageUploadedByRocketry Forum1486744749.662070.jpg

The hole is 1.4" diameter and about 1/4" deep. My original thought was to cnc a curved flange around a piece of 1/4 acrylic to match the inside of the tube, but a friend suggested that I pour the window inside the hole with a clear resin.

I would tape in place a sheet of wax paper or mylar on the outside of the hole, contouring to the OD of the tube, then orient the hole facing down and pour resin from the inside with a syringe. This would allow the resin to perfectly match the outside of the tube and leave me with a perfectly clear inside surface. I would have to go back and buff the outside clear.

The resin I've found:

Does anybody have any experience with something similar? This method is certainly much easier for me than machining acrylic.

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I've used jewelry embedding resins in the past. Be careful. Many of them yellow or turn cloudy over time when exposed to UV. Also, some resins are not water resistant. They will cloud when getting wet. Make sure you use a water and UV resistant resin like the Crystal Clear series.

It's also really tough to get a smooth surface that doesn't show distortions when looking through it. I'd suspect filming through the window would also show distortions. You'll need to polish with a felt wheel and very fine rubbing compound. I did that with a piece of jewelry made of deconstructed watch parts, and I still saw refraction and prisms when the sun was on it. Pretty! But not what I wanted.

It's really much easier to simply cut a polycarbonate disc and glue it in. If you do cut polycarbonate, you can pass a flame quickly on the edge to get rid of the opaque surface where it was cut. Makes it pretty.
Trace a circle the right size, crudely cut it out with a Dremel. Sand to fit. Flame the edge. Probably less than 30 minutes of work. Will take that at least that long to make sure you have a good mylar seal, pour resin, pray you have continuous mylar-to-resin contact or you will get voids on the surface, polish.
I ruined something similar to this. When I made this one, I simply hung it from a gold chain in a black felt shadow box. (lesson learned)

This was made from a forgery Cartier watch. When you turn it over, you see the Cartier name, and it freaks people out when they think I cut up a $15,000 watch. :lol: