A few years ago [Brian McCafferty] created a nice big RGB LED panel in a poster frame that aimed to be easy to move, program, and display. We’d like to draw particular attention to one of his construction methods. On the software end of things there are multiple ways to get images onto a DIY RGB panel, but his assembly technique is worth keeping in mind.
The technique we want to highlight is not the fact that he used table tennis balls as the diffusers, but rather the particular manner in which he used them. As diffusers, ping-pong balls are economical and they’re effective. But you know what else they are? An inconvenient size!
An LED strip with 30 LEDs per meter puts individual LEDs about 33 mm apart. A regulation ping-pong ball is 40 mm in diameter, making them just a wee bit too big to fit nicely. We’ve seen projects avoid this problem with modular frames that optimize spacing and layout. But [Brian]’s solution was simply to use force.
Observing that ping-pong balls don’t put up much of a fight and the size mismatch was relatively small, he just shoved those (slightly squashy) 40 mm globes into 33 mm spacing. It actually looks… perfectly fine!
We suspect that this method doesn’t scale indefinitely. Probably large displays like this 1200 pixel wall are not the right place to force a square peg into a round hole, but it sure seemed to hit the spot for his poster-sized display. Watch it in action in the video below, or see additional details on the project’s GitHub repository.
I made it in 2020 : https://iooner.io/ping-pong-led-frame/
What about cutting them not in the “middle” but a little bit upper, where the diameter is 33mm?
It is important to use ABS ping pong balls for projects like this. Do not use celluloid ones, those are ridiculously flamable and a couple hundred ping pong balls will cause a serious deflagration.
G’sus christ those flashing christmas lights.
Why. Just why.
to annoy the neighbors might be a reason?
to cut the energy bill in half when the flashing is at a duty cycle of 50%
it’s the default setting and nobody knows how to change it
the new setting is volatile and therefore set back to default when power turns on at 18:00
to screw up the camera settings, so nobody can make a decent photo or video
those blinkin lights were the only ones left in the xmas light store
You could also make a grid from cardboard painted with silver paint, cover it with semi-transparent paper (cheap printer paper or baking paper) and you have nice big square pixels with no bleed. If you print some mask on that paper, you could have round holes or bigger borders between pixels to add character.
I wonder if one attached two suction cups on either end of an ABS ping pong ball, dipped the ball in hot water or blew hot air and pulled the right amount if one could consistently get an ellipsoid with 33mm minor diameter.
I know I’m into “get off my lawn” territory, but… squeezing a pingpong ball is a ‘hack’ now?
painting the sides would keep the spill to a minimum. Also, as mentioned above make sure it’s a plastic pong ball.
Technically, celluloid is a plastic, just not a petroleum based plastic.
I work in biobased polymer research, and haven’t been able to find celluloid ping pong balls, except the very expensive match-grade ones. I wasn’t willing to shell out big money for something I was just going to grind up for testing….
https://www.ittf.com/2020/01/28/transition-celluloid-plastic-balls/
“With safety awareness growing worldwide, the flammability of the ball had become a risk driver.”
So, like, during a game? Cuz that’d be pretty cool to see. Like a high speed version of “hot potato”.