LED Diffusion Hack Chat

Lets get started! Thanks for joining us @Becky Stern ! While we wait for people to gather, could you tell us a bit about your work and what you do? and if anyone has questions they can go to https://hackaday.io/event/160157-led-diffusion-hack-chat)

mpinner3:02 PM
#sternSquad4evar

Becky Stern3:02 PM
Hi everybody! Thanks for joining the chat! I'm thrilled to be here.

David Hunter joined  the room.3:03 PM

Colin Alston3:03 PM
I work on ill conceived and mostly impractical RF electronics

Becky Stern3:03 PM
I make tutorials about electronics, crafts, and the combination thereof. I've made so many wearables using LEDs that I have tried out many diffusion techniques over the years! I currently work at Instructables.com.

Stephen Tranovich3:03 PM
Wahoo, Hi everyone!

Becky Stern3:04 PM
Many of the techniques I have to share are documented in my recent guide here: https://www.instructables.com/id/13-Ideas-for-Diffusing-LEDs/

Tom Hodder3:04 PM
Hello

Awesome. that link is great, theres so much there.

Becky Stern3:05 PM
Today I'd like to chat about paper, fabric, plastic, glue, glass, and 3D printing, just to name a few diffusion materials...

Our first question is about materials! from @Morberis " LDPE in sizes larger than 24x36 seems to have a yellowish tinge, at least from Mcmaster Carr. Do you have a thickness you recommend?" I think you recommended LDPE as a defusion material?

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Becky Stern3:06 PM
My background is in design-- I went to Parsons in NYC for undergrad, where I majored in Design & Technology. During grad school at ASU I started blogging for MAKE magazine and then went on to work at Adafruit and now Instructables.

sfrias13:07 PM
Great!! @Becky Stern Design->Adafruit->Instructables.

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Becky Stern3:08 PM
Low-density polyethylene (LDPE) is the type of plastic used to make shrink film and food packaging. I've never ordered it from McMaster but imagine you could use any thickness you want, depending on the application...

Becky Stern3:09 PM
Sheet plastics can be sanded to cause more light refraction

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Becky Stern3:10 PM
When you're just starting out, it can be helpful to visit a plastics store in person to check out the materials

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Our next question is from @Matt Ebel "I've been experimenting with pourable 2-part epoxies, pouring them into curved molds (silicone cupcake cups, etc) and then laying a NeoPixel ring on top of the liquid to create an attached lens that projects the ring's colors in specific ways. Right now it's all experimentation - I make a lens-ring combo, then I turn it on and place it facing a white sheet to see what kind of effect it has on the emitted patterns.

Is it possible to use tools like blender or other 3D software to reduce the trial-and-error aspect of a process like this? Are there resources to get plastic optical parts made either to spec, or in generic 'standard sizes' that would fit over common led-ring PCBs?"

Becky Stern3:11 PM
Here in NYC the defacto go-to is Canal Plastics, but I've heard folks on the west coast praise Tap Plastics https://www.tapplastics.com/

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Becky Stern3:12 PM
What a cool technique! I'd love to see a tutorial about your workflow.

Paul Stoffregen3:13 PM
yup, Tap out here for retail plastics :)

Becky Stern3:13 PM
hey @Paul Stoffregen!! The legend.

mpinner3:14 PM
*swooooon

Becky Stern3:14 PM
Using 3D tools, you could create your own mold forms or a jig that gets embedded with the LED ring that stands it in the right position in the mold.

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Chinna3:14 PM
Does anyone with 3D PRINTED LIGHT PIPES

Chinna3:15 PM
*wprk

Chinna3:15 PM
*work

terrag3:15 PM
I loved the part of your LED video where you demonstrated hot glue nubbin directly on a 5050 LED. Could you describe the type and level heat used to get good adhesion?

Becky Stern3:15 PM
You can get plastic parts manufactured but the mold tooling costs can be expensive: https://learn.adafruit.com/how-we-designed-an-injection-molded-case-for-raspberry-pi/

Becky Stern3:16 PM
@Chinna Light pipes use the same science as fiber optics, so I doubt FDM 3D printing would make a good one, unless we are talking resin 3D prints...

anfractuosity3:17 PM
that's interesting! i didn't realise the whole mould wasn't EDM'd

terrag3:17 PM
Do you think the hot glue applied directly to the 5050 LED could prevent the LED from shedding heat if the LED is on a surface that doesn't conduct heat very well?

It would be cool to get parts manufactured! @Mike Judge asks "Have you found any awesome off the shelf parts you can't wait to combine with LEDs but haven't had the chance yet? "

Becky Stern3:17 PM
@terrag Thanks! That's just my regular-old glue gun with multi-temp sticks, nothin' special. I was surprised it stuck, too, but upon inspection noticed the pixels' lens is a kind of soft plastic that I think melted a little when the hot glue touched it.

Chinna3:18 PM
Thanks Becky

Joshua Young3:18 PM
Formlabs now has optically clear resin for light pipe manufacture. You can buy off the shelf light pipes in pop them in your 3d printed thing maybe?

https://vcclite.com/product-category/light-pipes/

Becky Stern3:19 PM
@terrag why is everybody so doggone concerned about 5050 pixels and heat? They hardly make any at all. I have no reservations about encasing them in adhesive.

Becky Stern3:20 PM

Becky Stern3:20 PM
I recently made a little sampler board to test out some thermoplastic, which I have never used in a project before

terrag3:20 PM
Ok, thanks, I'll try it. Your sampler board is such a great idea!

Becky Stern3:20 PM
It comes in little beads and you melt them together using hot water. Moldable and dries rigid and white

Becky Stern3:21 PM

Becky Stern3:21 PM
@Joshua Young cool idea!

mike3:21 PM
+1 on the great sampler board. Is there any way to add color to thermoplastic?

terrag3:21 PM
I recently used some thermoplastic to fill the gap a 3d printed "shark fin" antenna cover on a car. It's still holding up well after being in the hot sun.

Lets try to keep questions https://hackaday.io/event/160157-led-diffusion-hack-chat here just so the chat flows a bit better and we can get all the questions answered!

Becky Stern3:22 PM
I'm not sure how to color it, this was my first time using it.

Becky Stern3:23 PM

Becky Stern3:23 PM
Here's some 3D printed (ninjaflex) diffusion

Becky Stern3:23 PM
You can see the LEDs only light up a small section of the print because they are touching so close

Morning.Star3:23 PM

Becky Stern3:23 PM
One of the most important tools for diffusion is space/distance

Morning.Star3:24 PM
This is what I use. Its called Polymorph. Never managed to colour it... ;-)

Becky Stern3:24 PM
Color it with LIGHT!

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Frank Buss3:24 PM
a colorful LED would color it, when powered

Morning.Star3:24 PM
Imma gonna have a go now XD

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Becky Stern3:25 PM
Another diffuser I love but haven't used nearly enough yet is PING PONG BALLS.

Becky Stern3:25 PM

Becky Stern3:25 PM
This piece is by Moritz Waldemeyer

Okay, @dante.rva has a specific question, "What would be your recommendation for shinning an LED through the back of a rhinestone? I had been considering using E6000 or a white silicone adhesive to diffuse the light. "

Frank Buss3:26 PM
I guess just the ping pong ball wouldn't work very good for bright small pointy LEDs, saw in your blog you used cotton as well

Becky Stern3:26 PM
Well E6000 dries clear (sometimes with some bubbles) but sticks to almost everything. The silicone may not stick to the LED or the rhinestone, and white silicone adhesive is usually opaque (does not transmit light at all).

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Becky Stern3:27 PM
@Frank Buss on the contrary, ping pong balls work great for small pointy LEDs because they have so much volume. The angle just has to be right.

Becky Stern3:28 PM
So @dante.rva I'd suggest E6000, if you want it a little cloudy, try using a toothpick to stir some more bubbles into it before applying.

Frank Buss3:28 PM
ok, will try it, but your unicorn looked promising as well

Becky Stern3:28 PM
Also double check the rhinestone has a clear back, the ones I've used for nail art have a shiny (but opaque) back.

Frank Buss3:28 PM

https://cdn.instructables.com/FJC/KX5R/JIYU21I7/FJCKX5RJIYU21I7.ANIMATED.LARGE.gif

INSTRUCTABLES

dante.rva3:28 PM
Clever idea! Thank you!

Becky Stern3:29 PM
Yes the unicorn horn is 3D printed, and the polyester fiberfill was used to keep the NeoPixel sticks centered inside the horn.

Joshua Young3:29 PM
google says ping pong balls are made out of celluloid, same thing as photographic film, so probably why they work so well.

anfractuosity3:29 PM
they use ping pong balls for the ganzfeld effect thing, because they diffuse well i guess

Frank Buss3:29 PM
the fiberfill itself would be diffusing as well

Frank Buss3:30 PM
I think I saw once a LED illuminated cotton cloud :-)

Becky Stern3:31 PM
That brings us to plush toys! My students have been making plush nightlights the last few years to explore diffusion materials/concepts: https://www.instructables.com/id/13-Ideas-for-Diffusing-LEDs/#step4

Becky Stern3:31 PM

scott.e3:32 PM
I find that oxygen/aquarium hose is the right balance of translucence to take the edge off an over bright row of LEDs. https://www.instagram.com/p/8dYrHgBHlJ/?utm_source=ig_web_copy_link

scott.e3:33 PM
A bit of hot glue to afix the hose to the multi-LED strip helps further disperse the glow.

Becky Stern3:33 PM
It's true that my former student Richard Clarkson turned this assignment into his first product and started a business around it: https://www.richardclarkson.com/cloud/

Morning.Star3:33 PM
Whats the furry one the guy on the left is holding? Its really bright :-)

those are great. i love all the different materials and techniques.

@Joshua Young asks "Do you have any design guidelines for getting uniform light dispersion? How many LED's per square inch vs materials. I would probably want the least LED's, so my material choice would be based of the highest even light vs number of LED's, but I don't know what is a good starting point of what works before you can see local bright spots. "

Becky Stern3:34 PM
@Morning.Star https://makingstudio.blog/2017/10/12/plush-nightlight-let-there-be-light/

Morning.Star3:34 PM
TY :-)

Joshua Young3:35 PM
cloud is awesome!

anfractuosity3:35 PM
yeah i was thinking that too, i love the grey cloud especially

Becky Stern3:36 PM
@Joshua Young this is a matter of personal preference combined with experimenting with what's available around you. I cannot give you a specific number of LEDs per square inch! What an absolutist question! =D Of the common LED strip densities, I prefer 60/m over 30/m but it really depends on your overall application! I mainly make small, human-scale things, not, say, a whole vehicle's worth of lighting.

Becky Stern3:36 PM
Designing projects is always a matter of balance between overall goals, power constraints, cost/effort

sfrias13:37 PM
Awesome!!

Becky Stern3:37 PM
If you need absolutely even light, LEDs are the toughest. Ask yourself first if you can make do with EL wire or even fluorescent lights

Becky Stern3:38 PM
If you have a project in mind, then I can suggest more specific materials...

Morning.Star3:39 PM
White Polyester fur works really well, I like that The fibres act like waveguides a little. Very impressive :-)

Becky Stern3:40 PM

Joshua Young3:41 PM

Joshua Young3:41 PM
cool, I always wanted to replicate this museum piece

Becky Stern3:41 PM
Oohh that's nice, who's it by?

Audi McAvoy3:41 PM
I'd love to see that fuzzy cloud slowly spinning.

Becky Stern3:41 PM
How have you folks tried diffusing LEDs in the past? Did it work or fail, and why? Calling out my quiet squad @Brian Lough @davedarko @mpinner @oshpark

Joshua Young3:42 PM
jim campbell, Street Scene 2006

Becky Stern3:42 PM
very cool low-res display

Materials seem to really be key here! @Scott Schubert wants to know about more stores in NYC, but are there also any online resources or specific products you'd recommend ? Where do you get your lights and materials ?

Joshua Young3:44 PM

Morning.Star3:44 PM
I tried a stream of water, which was interesting... ;-)

Morning.Star3:44 PM

Becky Stern3:44 PM
I have so much adafruit hardware leftover from working there, I don't have to shop often... so that means I'm working with a lot of NeoPixels in different forms (strips, rings, singles, sticks). I also like these WS2801s inside plastic diffusers: https://www.adafruit.com/product/738

Brian Lough3:44 PM
Hey sorry, also getting the little one ready for bed :)

Morning.Star3:44 PM
Thats actually a laser, but the principle is the same.

Becky Stern3:45 PM
@Joshua Young very cool! The front looks like frosted acrylic sandwiching some kind of black squares, perhaps they are printed on transparency sheet

Brian Lough3:45 PM
I've used opal acrylic (worked well), tried frosted paint on glass (didn't work)

Becky Stern3:45 PM
@scott

Brian Lough3:46 PM
I have a few small canvas pictures of NYC that I've been threatening to to illuminate for about 6 years, still on my to-do list :)

Becky Stern3:47 PM
@Scott Schubert There are some lighting supply stores on Canal street but shopping on Amazon is a similar experience in terms of availability (fairy lights, AC light strands etc.). I loved a store called Industrial Plastics that closed some years ago

Joshua Young3:47 PM
"Street Scene" In person it looked to be frosted glass, with black vinyl film taped to the back side. I nervous to recreate and commit funds if it does not light right....

Becky Stern3:48 PM
@Scott Schubert This guide has links to all the materials I recommend for diffusion lately https://www.instructables.com/id/13-Ideas-for-Diffusing-LEDs/

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