Feb 282021

80\20 T-slotted aluminum hardware rules, but it’s kind of expensive and even the 20-series is just a little too big to make sense for a lot of electronics DIY stuff.

Makerbeam is a 1cm profile series that should be the perfect compliment to 80\20, and at first glance it’s great and seems semi-affordable even for small amounts, but that’s just looking at the extrusions.

I got 4 sticks of 300mm MakerBeam for $18 to try out and thought- hey, this isn’t too bad. Way more than wood but this is reusable foreverish. But I mistakenly thought that a standard M2 nut could work in the slot. I was wrong. Pan head M3 bolt wont fit either, you need a square head bolt or a flat nut… no big deal, right? The M3-5 hammer nuts for 80\20 are like $10 for 50 so I can deal with that.

Nope- the makerbeam M3 flat nuts are freaking outrageous- like a buck each for about .01 cents worth of stamped metal with an M3 hole… freaking infuriating.

The whole point of getting this stuff is that I’m not a machinist, so if I have to start making my own fasteners this goes sideways fast. But… I figured out you don’t have to be a machinist to make something workable.

Just needed snips, drill, screwdriver, and a little file helped. A sane person that owned a functioning drill press would do even better.

Started with scrap copper sheet I’d pulled out of a laptop heatsink years ago (Hoarding heatsink materials pays off very occasionally). Cut off a strip thin enough to slide in the MakerBeam slot and drilled some M3ish sized holes. I don’t have an M3 tap so I just filed out a little and turned an M3 through it.

The surprisingly cool part is that even if the hole is off- when you put it in the slot and screw it down it does sort of a brake press action on the nut and it trues up in the slot. They’re not as strong obviously but if you’ve got loads that can tear copper I guess just pay the buck. I figure this could also be a decent alternative the brackets which are also outrageously priced, but actually I’ll probably just use 80\20 for most stuff because this isn’t trivial enough to make dozens of nuts whenever I need them so it’s actually not all that workable, just more so than paying $1 per nut.

Feb 232021

This is another one of those posts that I have to make so I can be ‘done’ with some ridiculous thing that I know I’ll never put enough effort into actually being done with.

At some point I thought it would be interesting to have a flat device that extended to a surprising vertical height using a flat coil like a tape measure. A little curl gives flat tape a little rigidity against pressure on the convex side. Thought maybe using two facing each other could give you enough strength to raise up a strip of LEDs. Figured that would be a cool effect right there- little lights that smoothly lift up out of the ground.

It’s kind of a dopey cousin of the ‘Kataka Actuator’. I promise I thought of this before I knew about the Kataka, but it doesn’t matter because they work completely differently. Also the Kataka has a lot more potential utility because it’s fairly strong and can lift useful loads whereas this is just for display type applications. Unfortunately the Kataka apparently suffers from intellectual property crapola that make it too expensive to be useful to anyone like me.

I finally put about a half-day into a crappy proof-of-concept and basically proved to myself that the tape-measure idea probably could work but I didn’t feel like working out all the mechanical kinks to make it actually work.

So here it is. The tape-pulling mechanism kind of worked. I had to coat the ‘drum’ with silicone caulk to make it more grabby. A tractor feed system with punched holes in the tape would be more ideal. The ‘turn block’ was trickier than I realized. I’d need to design a better contained but gentler pathway to get it to turn the 90 degrees upwards without binding up the whole feed.

And I put a little thought, but no design, into figuring out how to combine two tape-feeds into one ‘pole’. Figure the easiest thing is just mirror the whole assembly on the other side that meet in the middle to turn upwards, though driving that from a single motor gets more complicated.

Pretty sure I’m never going to get back around to this idea. Seems like someone with a fresher interest in stage lighting could make this a cool project, but I’ve got other obsessions brewing and I just wanted to post this so I can repurpose the arduino and motor, and also the box it’s been sitting in for 6 months because it’s a really nice box- not the blue one, but still nice. I didn’t post the 3d files because there’s why bother.

Feb 132021

As if I hadn’t taken this silicone LED thing to absurd enough extents… here’s more.

I came across a product called ‘Encapso K’ that I thought might be fun to test as an alternative to the acetoxy silicone I’d been using. I’ve found the super thick balsa ones never stop curing so they get bubbly and weird after six months or so. Plus I was just getting tired of the extreme goopiness of the caulking process. So I ordered a little kit of this new stuff. It’s two-part platinum cure that solidifies water-clear but is extremely brittle so it’s billed as ‘rubber-glass’ for glass and ice sfx uses. It lives up to the name too. It is clear as glass but cracks and crumbles kind of like a rubery stone. Crazy stuff.

Unfortunately I learned it will not cure inside of the vinyl tubes I use for the tube lights. I’m guessing it’s something about the chlorine in PVC being an asshole but I’m not a chemist. I could try acrylic tubes, but meh. And the liquid is too thin to make the balsa dioramas without precuring some little pieces to hold the planes in place like they use in resin casting and then it’s just resin casting with really brittle, rubbery resin. So I wasn’t quite sure what to do with the stuff for a while. The fact that it wouldn’t cure in the vinyl tubes was kind of a deal breaker for most ideas. And the brittleness wasn’t helpful.

Recently I thought it might be cool to encase the new brittle silicone in the old flexible silicone and then smash it and see what happened. And I did that. And this is what happened.

Pretty predictaby- it looks like fractured brittle silicone encased in a more flexible silicone, kind of like an ice cube.

So yay- I made a kind of an ice cube looking thing out of a couple of different mixtures of silicone. It looks really cool with an LED behind it I think. Maybe I’ll make a light out of it.

I did make a light with the same general idea using crushed glass in an upside down glass a while back. But I wasn’t a big fan of working with crushed glass. I used safety glass so it was little cubey grains but it still wasn’t great. And this way it looks like big chunks of broken glass but without dealing with big chunks of broken glass. So I ended up really thinking outside the box here by using this new silicone stuff to do exactly what it’s sold to do.

But the really surprising part of all this was finding out how fun it is to crack the interior silicone once it’s all cured up. Kind of hard to get the first crack in but once you do it feels like popping creme brulee bubble-wrap. Seriously- if you’re a compulsive folder or squisher or roller of whatever materials are around you- this is cosmic apotheosis. It’s kind of a one-time stress-ball, but it’s one hell of a time. The hardest part is stopping so you end up with a cool looking ice brick thing instead of a glazed snowball. I think I made the video mainly to show the cracking part. I always dig the LED stuff but wow- crushing up these weirdly squishy but crackly silicone bricks… glad I didn’t learn about this in my teens or I’d never have left the house.

Jan 032021

This is an attempt at a bot design that’s driven and steered by only one servo. I have no justification for this other than it seemed like it had to be doable.

I’m absolutely sure a single servo actuated steering\drive mechanism exists somewhere, but I couldn’t find any. I’m guessing the designs that do exist are for very specialized applications where some factor makes using only one servo desirable. Using two 9g hobby servos for any reasonable DIY application is pretty much as easy as using one, so there’s really no advantage in the added complexity of the linkages at all.

But despite it being a fundamentally pointless idea, I couldn’t get rid of it. A servo set up as a rear paddle of a canoe could control direction and momentum so why not a wheel? I thought about doing something like a ‘wheel paddle’ that would work a bit like a skate, pushing laterally to roll forward and varying the angle to each side to control direction, but that seemed like a copout somehow so I thought about more classic wheel\axle setups. This design is optimized for simplicity- lol… what that means is this is the minimum effort required to satisfy my weird compulsion to demonstrate this is possible, knowing I have no intention of taking it any further than that.

So the drive is a kind of rack and pinion thing with the teeth angled to turn the wheel on only one stroke direction. I should have used a little ratchet catch but didn’t. I’d seen more complex ‘mechanical rectifier’ setups that could drive on both strokes, but meh. I went with the T bar steering setup so you could kind of ‘set’ the direction and just work the servo around it so you can go straight and make smooth turns. Other options were to keep the steering connected to the servo but that would force it to always move in a serpentine pattern.

The video is a bit of a disaster. I tried to create the mechanism in the blender game engine using rigid body dynamics but I’m about 5 years out of practice with that program and forgot a lot so I just kind of winged it. The simulation is clearly jacked. The gear wheel doesn’t work right because I couldn’t figure out a directional rotation constraint and friction is wonky in the bge. Everything kind of floats, it’s awful, but I think it shows the functionality I wanted it to show and that’s the whole point of this pointless thing. I also tried to 3d print it, but… yeah- lot of quick-n-dirty solutions in the game engine version didn’t translate to matter so it didn’t really come together. But since I spent the time and the PLA I put it in the video too.

This obviously wasn’t a success, but I don’t think I can call it a failure either. Like a lot of my projects it kind of works in a way and if someone with more skill and determination took a stab it could probably be cool little demo thing. Anyway- it’s something I did so I could stop thinking about doing it so now I guess I’m done and I can do another thing.

Jan 022021

This light exists because a while back I bought some of that silicone-neon style strip diffusion and had to figure out something to do with it. Would have been cool to install the strip above a door or a footlight or something, but I rent so I don’t really do stuff like that.

So this is a pretty simple rig with (65) WS2812 LEDs on a D1 Mini running WLED. The structure is just a PLA printed holder that secures the strips and a small section of PVC housing the electronics. Originally there was a longer section of PVC and an 18650 battery module inside, but I wasn’t satisfied with the runtime with (65) LEDs so I just chopped it and went back to USB power. I popped in a mag-safe knock-off for the power supply. Those are really great.

I really like the diffusion these provide with 60/m LED strips. It’s not as great with 30/m and 144/m is very cool but probably overkill. They make several different profiles and focal patterns, I got this one by accident or mistake. I thought I ordered the circular neon style but this flat square style came so whatever. I’d love to make a larger installation of these on a staircase or something, but unless\until I own something worth a permanent setup I probably won’t be using this stuff very much. But now I have this little display piece to remind me how cool it would be if I ever did.

Jan 022021

This is just a little housing idea for an ESP32CAM and AM312 PIR sensor
A small section of 2″ PVC and PLA printed holder. Pretty simple and sturdy.
I’m using this indoors with hass.io, but the PVC housing might be a good basis for exterior cameras too. I’m working on adding a battery module and using deep-sleep modes to make long-term time-lapses but this worked out pretty well so I figured I’d post it.

Here are the STLs:

Jun 132020

Here are more silicone tube lights with increasingly unlikely balsa gliders.

Here’s a video I made of the process of making the lights.

The classic toy ‘jetfire’ style balsa planes are aesthetically perfect to me. Form and function in unity. The little nose weights complete the look in the miniatures and it just looks great suspended in silicone all by itself. Add some swirly powder and LEDs and you got some staring to do.

But of course I can’t look at a balsa plane and not think about planes in general, so I started considering other possibilities. I’m not an aerospace engineer or an artist, so I thought about air frames that were very visually distinct and ones I liked just because. So far I’ve found three variations that worked out pretty well.

CTS (Cellulose Transport System) Orbiter – Psych! It’s the Buran! Sort of, not really, doesn’t matter. It is technically a glider air frame, but I positioned it in an orbital orientation so it’s not even pretending to glide, but whatever. It’s geometrically distinct and close to my heart, so this was inevitable.

P-38 Torchlight – Very distinct geometry. Very little sense as a glider. But it’s undeniably cool and was a very capable airplane so I gave it a shot. Turns out it’s pretty easy to make and much stiffer than a typical balsa plane so it’s easy to reposition in the silicone without fear of twisting the wings.

SR-71 Woodpecker – Negative zero glider sense here. Gigantic inert nacelles are not a thing. But who doesn’t love the borderline sci-fi aesthetic of this historic aircraft? I got the general shape and quit. Didn’t know how to make the inlet cones or afterburners and anyway it’s a balsa wood model of a supersonic jet so seemed good enough.

Not sure what’s next. I tried a biplane but getting silicone between the wings without voids is problematic. Not sure I’m ready to go full sci-fi balsa spaceship but it does seem like that’s on the horizon. I’d love to think I can carve Serenity or the Enterprise but I’m pretty sure I can’t. Maybe an X-Wing though, we’ll see.

Also I am willing to sell these but don’t care that much. Etsy seems like a waste of time and I don’t really want to deal with typical consumer expectations. But- if you want one enough to contact me about it- there’s a good chance you’ll get one. I’m thinking in the $100 range is enough to motivate me to put one in a box for a stranger, but if you’re a cool person and have an interesting reason for wanting one that’ll motivate me even more. They do take for freaking ever to cure though, like months. So if I make one custom don’t expect it for a good while.

Jun 012020

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

May 142020

UPDATE: Pretty much resolved the stability issues with the ESP32CAM and posted it on github – https://github.com/funkboxing/espcreep

Here is the first semi-functional build of a bot type thing I’ve been working on. I’m calling it ESP Creep, because it’s ESP based and it kind of creeps.

ESP Creep demonstrating how poorly wheeled vehicles perform without friction.

It was made to have a minimum part count and be simple to assemble and control. I’d like these to be available for anyone who wants an extremely inexpensive robotic camera platform. I always envisioned some kind of desktop multi-bot ‘soccer’ platform to help learn and play with vision control systems and such, but there weren’t any cheap-o bots that really fit the bill. This isn’t ready for much except more development, but it does most of what I intend it to do, albeit very poorly, so I figured I’d share.

Here are a couple of obligatory glamour shots of the bot. Just look at those unnecessarily long, flowing servo leads… majestic.

These are the parts involved, sans 3d printed parts and a half-dozen 8mm m2 screws.

~SG90 Hobby Servo (Angle)
~SG90 Hobby Servo (Continuous Rotation)
~16340 Battery Module and battery
~1000uf (6.3v) Electrolytic Capacitor
~Breakout PCB and Connectors.

The PCB breakout is the only custom part, and it’s not strictly necessary, just very convenient.

I chose not to do the traditional differential drive. I’m not entirely clear on why I didn’t want to, but I’ve rationalized it with a few apparent advantages. One it’s just easier to handle control wise. There’s no need for ‘mixing’ turn and throttle variables into the motor values. This just makes it +/- for drive, and +/- for turn. Also you don’t have to calibrate motor speeds to make the thing go straight. Mounting the motors for differential drive seemed to make the bot footprint larger, or wider at least. Also I like that it makes steering pan the camera. And I can’t always find continuous rotation motors and I hate modifying angle servos.

Obviously the next step in the 3d design is to get some friction happening on the wheels, and tighten up the wiring situation.

The big problem is the ESP32CAM software. It serves up the camera and parses UDP packets to command the servos. You can see in the video at the end the connection drops. It does that about 30 seconds after you connect. Sometimes I can reconnect right after, but sometimes I need to reboot the ESP. I know the ESP32CAM can be fairly stable because I have several running esphome on hass.io. But I cannot get these things to stay connected with Arduino based code. Some of it might be the motor power demands, the ESP’s are a little finicky with power, but it’s not consistent with motor power, it drops when it’s just sitting there. I added a big honking cap that I think resolves any brownouts but I don’t think the ESP is rebooting because I can still ping it right after it drops the camera connection. I can’t get any error output when it’s connected to serial that gives me any clue what’s happening. But I’ll keep working on it, I’d love some help if anyone ESP savvy has any ideas.

Here are the files. These are not really well organized. It’s everything you’d need to recreate this bot, but it’d take a pretty handy person to get it all working. I would love it if another DIY nerd wanted to jump into this, especially the ESP32CAM arduino sketch. Fair warning this is terrible code and I express my frustration in comments and variable names. Also I can’t find the stencil files for the PCB right now, but I got it made by OSHPark so they’re still up there. Eventually I’ll get more and maybe sell them in kits or something, but if anyone wants them just let me know, I think I can get the files from OSH. Also it’s just breaking out power and data for the servos so anyone could reproduce it.

~Blender 3d File
~Arduino Sketch
~Python File (keyboard control)

May 112020

No wise man ever said “You can’t start trying to make warp coil lights and get caught up in a whole other thing with the stuff you started making the warp coil lights with and then not eventually get back to warp coil lights.”

And you know what? They’re right- because nobody should ever say that, and that’s exactly what I did.

THERE ARE FOUR LIGHTS!!! on the right, and three on the left.

This is another warp coil light, this time with WLED but I haven’t added the warp effect loop yet, this is just WLED onboard effects. If I haven’t mentioned it enough- WLED rocks the\my casbah and\or world. The video shows the original warp coil light on the left and the new warp coil light on the right.

I wanted to take a video with the new warp light running the ‘warp’ loop, but somehow it became a familiy reunion of all the 3/8″ tube lights. The shotlight build hasn’t gotten much love lately, not sure if I’m going to get back to it, bit of a lark, but it does look cool next to it’s cousins. #TUBELIFE

Interestingly, the old tubes seems to do a better job of transmitting the light around the curve and I’m not sure why. The old light and the silicone is only a few months older than the new one, but the actual vinyl tubes I used for that light were ones I’ve had for years. I think that roll of tubing had been sitting in my parts bin for a decade. I do notice the older vinyl has a slightly yellowish tint. I’m not sure if that’s from the factory or from sitting and accumulating layers of tobacco smoke. Whatever it is, I wish I could duplicate it. You can almost tell in the video that the middle of the new light doesn’t get quite as much light, but the old one is pretty even throughout.

Anyway- the new one has four coils instead of three because THERE ARE FOUR LIGHTS!!!