Geometric beast

Amazing project. Thanks for share.

Would you mind sharing what software you used to createthis?

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Pretty simple in terms of software:

Sketchup for calculating angles. (Nobody loves geometry and/or trigonometry this much)

Inkscape for tweaks and layout into a cutsheet.

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Geeeez! Cool orb! :sunglasses:

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Wow… that’s pretty incredible. I can’t even imagine the math involved in figuring out those angles. Truly impressive.

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That’s amazing! What kind of light are you using that throws shadows that sharp all the way across the room?

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Generally shadows get sharper as the light source gets smaller (or more focused), so in this case, I was using a super cheap red LED flashlight.

Basically one of these, or its many many clones:

I unscrew the lens assembly which exposes the (quite small) LED inside, and you get about 180 degrees of fairly radiant light, so it throws nice clean shadows for a good ways.

These lights aren’t the brightest necessarily but they are decently good throwers and super cheap (if you have the batteries, like 2$ sometimes). I keep a few around, they make good car lights and whatnot. They can run off single AAs, but for best results (far brighter) use a lithium rechargeable 14500 battery.

Anyway to setup the shot, I just stand the light up on its butt inside the piece, then carefully position the camera so the LED is blocked, thus avoiding a massive hot spot on the pic. Turns out pretty nicely, those are all straight off my iphone with no post processing.

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Ah, yes; bare LED. Was figuring it wouldn’t look that nice with a
full-sized bulb. Thanks!

Yeah a traditional diffused light bulb would muddy things up pretty badly. Even a clear bare filament bulb would not be a great option, so a single LED is what’s up. I wonder if there’s a light source specifically designed for this, with a clever lens that throws light in a more collinear fashion on a larger degree spread. Someone out there must know how they do this for like planetariums and whatnot?

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Well, that’s a bit of a contradiction. What is needed is a very small diffused LED that throws light over a wide range of directions, with the least collinearity.

Radially symmetrical? Single-point origin? That what throws good shadows?

Semantics aside, I’d hope the gist was gotten.

Not semantics, the exact opposite of what you want. Collinear light would shine in just one direction!

“More collinear”. Oh internet, is there nothing that can’t be picked apart? I do own a laser cutter and use 3d modeling software, the term collinear hasn’t passed me by.

Anyway see above re: gist.

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Rather than continue the back-and-forth chatter here, I’ll PM you.

But for those shopping for an LED that will cast great, sharp shadows, look for one with the least collinear radiation pattern, which normally goes by the name “diffused.” And the smaller the diameter of lens, the better.

This is a good choice in my opinion:

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While these clear-lensed units are a bit better than their translucent equivalents, they tend to throw their light in pretty uneven patterns (a circular hot spot with very little diffusing beyond) and so wouldn’t work in my case. If you’re projecting an image, however, this might work fairly well in dim environments.

They also won’t throw enough light to function as a lamp. For something brighter, the current best I’ve found have been the standard star shaped emitter boards, you can take your pick from any number of models (I’m a Cree brand guy) but going for the smallest die you can find that will give you the lumen count you’re aiming for at the voltages you’re prepared to provide gets the best results.

Of course as you go brighter, you have to consider heat dissipation so you get into sink design, and form factor becomes an issue… it gets to be a game of compromises pretty quickly.

I have a few clear 5mms laying around, I’ll keep them in mind if I need a smaller directional light source in a project, they might come in handy.

The examples I cite above aren’t clear LEDs. The “diffused” means they are translucent.

Yes, they will be dim compared to the Cree stars, which are great if you want to have bright sharp shadows in a particular direction. The ones I cited above will be better for night lights.

Another good source I’ve found is here:


Ah, right, I looked at the pic and they looked pretty clear on my phone. The price of moving quickly, I suppose.

You’re right, those would approximate a pretty small point source, so might throw decent shadows in certain situations. I find that in general LEDs this small don’t have much practical application beyond being indicators – they just don’t throw enough light for what I’m usually trying to do. Still, handy to remember them in some situations.

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have you tried plexi?

No, but I bet it’d look cool.

you can also bend plexi if you heat it with a dryer and make a jig for the angle
just something to think about
might be cool for next exploration

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