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Loads are hard to estimate, but maximum I guess could be 60kg or so...but as I said it could act in a number of directions.
Nominally, think of the tube as a prop, so in perfect use it’s loaded down it’s central axis, compression only. However in practice the tube may not always be vertical so there could be elements of flexural and torsional forces, but no tensile load.
The outside of the tube needs to be black, including the design. At the moment I’m putting a 20mm frosted acrylic tube inside a 25mm Carbon fibre tube and filling the void between the tubes with crystal clear polyester (no, this probably isn’t the best material) with about 20% ATH powder added (the powder gives some opacity which helps diffuse the LEDs).
Once the resin has cured, I stick an led assembly down the middle and cut the design with a dremel until I can see the light shine through (ensures I don’t go through the tube completely). At this stage the design is very visible even when unlit which is aesthetically displeasing, as well as being rough to the touch; hence I reinstate the design with clear polyester, this time with no ATH but instead some translucent black pigment. No, reinstating a design on a curved surface is NOT easy with a very fluid resin, but I’m working my way towards fixing that.
The idea for the 80gm weave was two-fold. I thought it might add some strength, plus I thought it would provide the diffusion that the ATH powder currently provides, without the settling out that is a problem with the ATH (one of my solutions to introducing the resin is to stand the rod vertically and fill it from the bottom using a syringe, so the design is effectively 1m deep, meaning there’s a lot of gravity at work!)
I’m toying with the idea of filling the void between tubes and the design at the same time, which would give more volume to fill and cast the etched design monolithically with the void fill material, effectively locking the two tubes together.
I’ve also thought of using an inflatable bladder as the central tube, meaning it could be deflated and removed leaving only the resin behind (and also meaning I could add the resin with it deflated, then inflate it to “press” the resin more effectively into the void and design).
Right now I’m doing a lot of thinking, not much doing! Sorry that I’m still being vague about the application, but I think there’s a gap in the market for this, but with low entry requirements...someone who already has more knowledge/experience than me could launch a product quite quickly, so I want to keep the exact application to myself for now.
Hopefully though I’ve outlined what I want to achieve above, but to recap;
Must be strong.
Must be uniform black on the outside until the LEDs activate.
Design “windows” must diffuse the light (think of it more as a backlit screen - as long as it glows light transmission isn’t that important)
Void down the middle must be maintained and I’ve discovered for the purposes of diffusion, the LEDs can’t be pushed right up against the “screen” material or they just look like point sources; need at least 10-15mm of clear air between them.
All suggestions as to materials and methods gratefully received!
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