funkboxing

I’ve learned a lot about acetoxy silicone, but most of what I’ve learned is I have no idea what’s going on and I just try to make it do something resembling what I want, but not be too picky. I haven’t found much information online about using silicone this way, so I figured I’d make some notes about it.

DIFFUSION
Silicone make a uniquely perfect transparent diffusion. It somehow transmits and bounces enough light that a few LEDs can fill up a volume with light, and show a little of the ‘beam’, but the volume remains transparent. I’m not sure what makes it so perfect, but I’ve tried several other clear fluids and this silicone does this kind of diffusion better than anything I’ve tried. And so far this DAP Ultraclear acetoxy cure silicone is the only kind that’s water clear and still workable. I found some loctite adhesive that’s as clear, but it’s a different chemistry and hardens weirdly and just doesn’t work, also it has a slightly yellowish tint. I guess epoxy resin might have a similar effect with light, but it’s expensive and I think UV messes with that over time. For whatever reason clear silicone just makes a beautiful substrate for lighting little miniature scenes.

CURING
As I understand it there’s something called ‘cross-linking’ going on where H20 molecules are exchanged from the air with acetic acid in the silicone. That process is what solidifies the silicone. I only have the vaguest idea what that means chemically.

When you lay in the silicone as thick as the balsa tubes, it seems to ‘self-heal’ any interfaces between silicone layers. Very small bubbles in ridges between ‘beads’ tend to go away quickly. Bubbles up to about 3mm in diameter seem to go away within about a week.

I’m not sure these tubes will every fully cure. So far the oldest tube I have is about 4 months, and it’s still a bit malleable in the middle. You can push the whole scene up or down a few mm by pressing the ends. Pretty sure it’s just forming a ‘plug’ of cured silicone that eventually gets large enough to stop any deeper curing. But it does keep going for a while. I’ve found if I seal the ends flush, within about a month I’ll need to ‘top off’ the tube because it’s shrunk about 4-5mm in. I’ve started adding a layer of cling wrap once they’re in the lights but I’m not sure if they’ll just slowly shrink for years and end up looking crazy with big domes pulled in from either end.

Pre-cured silcone slabs with powder and glitter seem to blend into fresh silicone over time. The interface disappears within a day and you can only see the inclusions. I’ve pulled dioramas apart after about a month and it seems like the pre-cured silicone softens considerably. When pulling apart the silicone it has a uniform viscosity in the center, even in places where the pre-cured silicone layers were previously very solid.

I’ve had no big breakthroughs in speeding up the curing process. I haven’t been very scientific with control groups, but I have some observations:

MOVING AIR – I just put a fan on it. Seems like that has to do something. If you leave curing silicone in a closed space it starts to smell strongly of vinegar, so makes sense clearing that out with a fan might move things along.
MOISTURE – I’ve tried submersion, vapor, and mist. Submersion does nothing, almost seems like it prevents curing somewhat. Vapor and mist seem to help harden up the outer layers, but I don’t know if that’s actually bad for curing deeper within the silicone. I do notice that if you put an older tube in a closed space with a mister, it starts to smell more strongly of vinegar than in a dry space. So maybe it’s doing something and I’m just too impatient.
HEAT – I left them in my car on a hot day, submerged in nearly boiling water, and used a USB heater to keep them about 60C for a day. I destroyed about 3 tubes in the process. The PLA gets soft about 80C and things get weird. I might try to keep it closer to 40C for a day or two, but so far seems like heat causes more problems than it’s worth.
UVC – I got a 8W UVC tube light. Made a little black out box and stuck it in with a tube. It does something because you smell burnt rubber as soon as you turn it on, but after a couple of days it didn’t seem to cure any faster and the PLA was starting to fade. I’m guessing the UVC only penetrates a little bit and just cooks the silicone on the top and does nothing deeper in. Anyway I knew it was probably a bad idea, but I had the light and couldn’t not try it.
PRESSURE – I have a USB food vaccum pump that I was hoping would help get some bubbles out, but it doesn’t. I would like to see if possibly raising the ambient pressure a bit could help speed the curing process. Ideally a small chamber capable of 2-3atm with humidity and heat control, but I live in an apartment and my kitchen is insane enough as it is so that’ll have to wait.

SOLDER CLOUD
The ‘nose weight’ on the balsa planes seems to create a yellowish cloud over time. It takes months and isn’t very noticable, but it’s very consistent. It expands out perfectly radially around the nose weight. Something is leeching out into the silicone, possibly tin or the rosin. You can only really tell with the LEDs off and held up to a light, so it’s not a big deal, but I may try to find a different material for the nose weights.

WATER
Keeping your fingers wet allows you to handle fresh silicone to some degree. It’s useful for smoothing and patting layers into each other. But it does seem to introduce a cloudyness in thick silicone. You can only really use water on the outer layers.

G-FORCE
I figured I could move things around in the silicone with a kind of centerfuge so I made a kind of sling. As a test I used a 6″ section of 1″OD tube filled with fresh silicone. I put a couple of bismuth beads at the top. I figured if anything would move in the dense silicone it would have to be pretty dense. Very rough calculations of the radius and rpm spinning it by hand I got about 9G’s and kept that up for about 20m. I manager to move the beads all the way through, but they jammed up against the tube wall as they went down. I figured there’s no way to use that so that’s about as far as that whole thing went. I’m sure a more precise and powerful centerfuge could do better, but not sure if there’s a point.

CLING WRAP
Counterintuitively, cling wrap is the best material I’ve found for kind of ‘molding’ silicone. I tried aluminum foil and wax paper. Foil tears when you try to get it off, and wap paper leaves a residue even if it doesn’t tear. I also tried thicker sheets of plastic and the silicone tears when pulling it up. Cling wrap is flexible and strechable enough to remove from silicone if you let it shrink onto it. It doesn’t work as well if you ‘pre-strech’ the cling wrap like a canvas. It also works okay on fresh silicone if you peel it back very quickly. It will stick, but it leaves a fairly smooth interface.

GLYCERINE
I need to do some more testing with this as a release agent and such. I also wonder if a a ‘vape’ device generating glycerine vapor could help speed up the curing process, but haven’t figured out how to test that without things getting very messy.

SILICONE MOLDS
I ordered some of those molds they use for epoxy resin, but they never came in. Still not sure if these would even work or if the silicone would bond too well. They do make some cool shapes though so I may still give these a shot.

OTHER STUFF
I think I’ve tried injecting pretty much every household chemical I have to see what everything does and looks like when injected in clear silicone. Most stuff just looks like what you’d expect. vegetable oil, bleach, various glues, other silicones, detergent, goo-gone, acetone, and my favorite experiment- alka-seltzer. Nothing really did anything that interesting, execpt alka-seltzer- I ground up a couple of tabs and cured it in a tube for a few weeks, then injected water into it. It did about what you’d expect- just slowly pooed out the silicone. It was unimpressive, but worth mentioning I guess.

My recent experience with WLED has made me think all these years coding out FX loops were a monumental waste of time. I should have just waited for WLED to exist. Not really, I learned a lot, but WLED is seriously the benevolent overlord of LED control code, and of course it includes the godfather of LED code- FastLED. I know I can gush over awesome open source projects, but WLED is a transcendental gift to reality. I have been looking for and vaguely pretending to plan to code something like this since I started playing with LEDs, but this is far beyond my abilities as a coder, or a human being. Anyway- WLED is the alpha and the omega for LED projects. So I’ve been smartening up a couple of dumb lights with it and smiling and clapping at some for the first time in a long while.

Here’s a video of a few lights running WLED, but it doesn’t demonstrate a fraction of the control options or effects.

I’m still really digging the hextube configuration. I don’t really plan on making more of them because it’s kind of quirky and I don’t think many people would be into it, but I really dig it but I haven’t been able to figure out a good FX loop for it, so I gave it an ESP8266 brain and took it to WLED university. Now I can control it with QLC+ via E1.31, but the onboard WLED FX are pretty wicked too. WLED lets me define different sections of the strip to do different FX, so I defined ‘segments’ for the outer tube LEDs, the area LEDs, and the inner tube LEDs and set them all to slightly different loops and pallettes. The video shows ‘wipe’ running on the outer and area LEDs but with different timing and opposite directions, and ‘plasma’ running on the inner tube LEDs. I think it looks pretty cool. I don’t even want to start parsing out how I would recreate this loop in an Arduino function, and now I don’t have to- and I might never again.

The video also shows an 8×8 LED matrix I built a while back using WS2812B strips, the bluetooth breakout board, and about 20 lbs of acrylic. I have no idea why I thought 3 sheets of 1/2″ acrylic were appropriate for this, but the thing is solid. It’s been running the fire effect 24/7 for at least the past 5 years. It was pretty trivial to swap out the Nano board for an ESP01. I also added a capacitor across the +/- just because I’ve learned you should do that for larger displays. The display is just running ‘plasma’ on very low brightness to let the hextube shine.

And there’s an obligatory balsa tube because it’s running WLED too and balsa tubes are just my jam now. I modified the WLED source to add the little crossfade effect loop for the balsa tubes so it starts up running that and it’s selectable and dimmable in the webUI. I’m having a little trouble figuring out how to handle the WS2811 PCB LEDs with WLED. I want them to stay off for regular onboard FX and only use them in the custom FX, but if I put them in a different segment they don’t work in the custom FX either. It’s not a huge deal but I’d like to get it straight.

I would like to take this opportunity to give the hextube a more fitting moniker since I’ve called several tests and builds ‘hextube’. It’s become a bit of a ‘my grandfathers axe’ situation with the parts but I think it’s going to stay what it is now. So I’m going to start calling this particular build SEVEN.

In the past I’ve worked with bluetooth and serial remote control of LEDs and I cobbled together a system to control LEDs with UDP packets at some point, but I never landed on anything I really liked or found useful for more than just a rough test. I’ve known of DMX\Artnet for some time but never understood it or cared enough to implement it. Well I finally dug deep enough to get an ESP8266 controlled by QLC+ and it’s pretty sweet. I’m not a huge fan of DMX512 from an structure standpoint- 512 bytes per universe and channel\address offsets and all this are just archaic nonsense, but it is pretty simple and ubiquitous so it probably makes more sense than the wacky bespoke UDP nonsense I was cooking up. I also looked at MQTT and it’s probably superior, but it doesn’t seem as universal for lights as DMX\Art-Net.

I had to edit a bit to handle channel\address offsets I can send commands in the same DMX ‘universe’. I’m not sure if it’s best practice to make each light its own universe, but I thought using one made more sense for my needs. I’m still a little rough on how the Art-Net nets, subnets, universe, kilouniverses or whatever are supposed to be structured, but I’m thinking that only matters when you’re controlling a lot more lights than I ever intend to.

This next video is 3 lights, each with an WS2812B 8LED ring on top and some kind of LED on the bottom, left to right they have a 3-UVLED WS2811 PCB, a 3-WhiteLED WS2811 PCB, and a WS2812B UV LED.

And for some reason here’s a picture of one of the tubes right after putting the silicone in. Silicone this thick is relatively forgiving with small bubbles, as you can see from this image the initial ‘pour’ left some ugly voids but after about a week of curing they disappeared completely.

“Silicone is optically compassionate but tactilely sociopathic.” -Banksy’s neighbor’s friend from the hardware store.

I’m using this Arduino library – https://github.com/rstephan/ArtnetWifi. At some point I’ll write a DMX client sketch that includes codes for running onboard FX modes, but for now I’m just using individual RGB channels.

Part of the problem I ran into controlling LEDs with WiFi was lack of a suitably convenient board. Most of the cheap ESP8266 boards run at 3.3V and I’m too lazy to add a level shifter to every build. Some board\LED combos will still work at 3.3V but it was too inconsistent. I found some 5V ESP32 boards that worked but they were less cheap and I didn’t like how hot they seemed to get just driving a strip of LEDs. Also had trouble with some of my goto libraries working on ESP32.

I did find these ESP-01s RGB modules and they work pretty well, but they only break out one pin so I can’t drive APA102 or add a button or anything.

I’ve also been sitting on a half-dozen of these ESP-01 TX\RX adapter modules that I originally got to add WiFi capability to a Nano. But I never got the AT mode to communicate with the Nano, and it’s kind of dumb anyway since the ESP is a perfectly capable microcontroller, the Nano just adds 5V and more IO pins, but I was only using 1 or 2 pins, and I could get 5V IO a dozen other ways.

Not sure why it took me literally years to realize this, but those modules also make the ESP8266 into a perfect WiFI LED driver board. It takes 5V and gives the ESP 3.3V, and the the TX\RX lines are already level shifted to 5V. You just have to add a line in the setup() function to define the TX\RX lines as GPIO:

pinMode(1, FUNCTION_3); //GPIO 1 (TX) swap the pin to a GPIO.
pinMode(3, FUNCTION_3); //GPIO 3 (RX) swap the pin to a GPIO.

Add a little MicroUSB connector and you’ve got a cheap ESP8266 LED controller with 2 IO pins. It’s a little annoying to code because you can’t just leave it plugged in to the USB and keep uploading new sketches like you can with a Nano or something. But I just have 2 ESPs and work with the protoboard plugged into a USB battery and the USB-ESP programmer to the PC and just keep swapping the ESPs back and forth. Alternatively for some things you can write code on another board like a NodeMCU or Lolin32 and just upload it to the ESP8266 when it’s good to go. I have a lazily iterative process so it’s easier for me if I can just change, upload, change, upload, etc, with as little delay as possible. It’d probably be better if I just thought things through more, but if I did that I probably wouldn’t be doing any of this in the first place.

So anyway with that rig, the ArtnetWiFi library, and a tutorial on QLC+ I quickly achieved my dream of finally becoming a a lighting designer for a portable micro airshow. Now I am content… but only just now… yeah it’s over, I’m not content anymore so I guess I’ll get back to tooling around and messing with stuff.

This is a video I created to demonstrate\promote these little lights I’ve been making.

I’ve got a fairly consistent process for making a few different styles so I’ve decided to call the main ones BLOOM, FLAME, and CLOUD. One-off experiments that work out enough to put in a light will be GUMBO. The larger fresnel lens tubes with little scenes will be SPACE.

I have no idea if anyone will think these are cool enough to spend actual money on, but at this point I pretty much have to start selling them just to justify continuing to make them.

I still have a little sorting to do but I plan to have the first Etsy listing of one of these lights up within a couple of weeks. Still not sure about a price, I’m thinking in the 60-80 range.

If you are an Arduino\electronics person and want to try writing some cooler FX loops or replacing the ATTINY85 with an ESP8266 for WiFI control let me know and I’ll see about sending you one for testing.