I seem to be a bit behind the curve compared to other testers, my hardware hasn't shown up quite yet (tracking predicts it'll show up today, so maybe I can get it unboxed and plugged together this evening - we shall see). But that doesn't mean I've been sitting back doing nothing. There's more to my project than just electronics after all!
After playing with the necessary 3D design, and printing one unfortunate failure, I realized I was taking the wrong approach to wrapping a flat string of LEDs around a spherical object. A spiral pattern just wasn't going to work given the LED strip's inability to bend along its thin edge. Being the intrepid rapid prototyper that I am, I mulled it over, and decided to give longitudinal mounting a try instead.
Here's attempt number two, printing away:
With a little bit of math, and a little more 3D modeling, I came up with a working design. Each channel is essentially made up of 11mm wide strips of a 40mm radius sphere incised into a 42mm radius sphere, that channel is then rotated 72 degrees around the center line of the sphere, and the process is repeated until there are a total of five channels. That may sound a little confusing, but the practical upshot of this you get five channels that will hold the LED strip and that are sized specifically to fit two segments of the strip (i.e. six LEDs per strip, and 30 LEDs per ornament).
My hope is this will give a relatively even lighting effect on the final ornament. But we will see.
You can see that in addition to the incised channels, the inner sphere has five raised nubs at points 45 degrees up the arc of the sphere. These will provide additional clearance between the inner sphere and the outer shell of the ornament to make for easier mounting of the LED strips and wiring.
Each 6 LED segment will have to be wired to its neighbors, and then each ornament will have two sets of wires coming out of it. One to hook to the supply (or the previous ornament) and one to hook to the next ornament. The holes in the top and bottom of the core will be useful for wire routing to keep the surface clear of stray wires.
One thing I discovered, but wasn't surprised about, is that the sticky 3M backing on the LED strips seems to be all but worthless. If there's anything it will stick effectively to, PLA plastic isn't it. I'll probably end up having to tack the strips down with hot glue or odorless silicon or something.
The only thing missing from the ornament now is the outer shroud. It's mostly designed, but not quite finished, and will be printed in nylon for a nice white diffuser layer that has a nice smooth texture to it.
Now... if only my hardware would show up I could put it through its paces and make a glowing ball...
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