Browsing posts in: LaserCutter

Skiing penguins build log retrospective

My skiing penguins project has been up and animating for a few weeks, and I thought I’d write down the process for others so that they can learn from what I did. And also so I can remember what I did and why. There are some other blog posts that talk about some of the specifics for the sequence controller I built.

First off, there’s a video here that shows the final result.

The my initial idea was to do something with LEDs and single frame animation; see some of the animations that were done at ZooLights at Pt. Defiance many years ago was what got me into this hobby. I had a big garage roof that was unutilized, and after some discussion with my wife we decided that skiing penguins was a good place to start.

CAD

 I started looking around for online penguin designs to use as a starting point and found a couple. Then I started up Fusion 360 and created a new project.

I design (and sell) LED ornament kits, so I’m used to doing these designs. Here’s a video that shows the technique that I use to space the LEDs out evenly along an outline; that is what I used for all of the penguins. Here’s a in-process look at one of the designs:

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and a final one:

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The final designs were too big to cut in my laser cutter (glowforge), so I had to break them into two pieces. The puzzle-piece line gives me two individual pieces to cut that can easily be put together again.

The animation has 15 frames, which meant 29 individual pieces to cut.

Cutting

I figured out what sizes of plexiglass I needed and bought the plexiglass from my local TAP plastics; it was about $90 worth. I didn’t want to spend a lot of time splitting pieces on my table saw, so I defeated the door interlock on my Glowforge for the larger pieces:

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You really shouldn’t do this if you don’t have laser safety glasses designed for your particular laser’s frequency. In this case, I wore my normal safety glasses and closed off as much of the opening as possible; I now have a nice set of dedicated laser safety glasses. Don’t do this unless you understand the risks.

Here’s all the cut pieces stacked up:

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This is a penguin prototype:

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This was actually constructed earlier; it was used to determine size, and we decided to go about 25% larger. Thankfully, Fusion made this fairly easy to do.

Here’s the first production frame:

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You can see the glue residue along the joining line. At the left and right sides there are short connectors that overlap the joint and provide much needed stiffening; they are on both sides. The squares with holes are spacers; the penguins will mount to wood supports and the spacers hold the wood away from the wiring that will be on the back. Zoom in to see the fine details.

Here’s the pile of penguins all glued together and ready for LEDs.

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First light on the first frame:

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Green was planned for the body outline rather than the white in the prototype but I didn’t have enough green LEDs at the time. The LEDs are brightness matched to look similar to human eyesight though the blues look too bright to the camera. Only 13 more to go!

Here’s what the penguin looks like with the leds off:

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Sorry about the messy and distracting background. For each section of LEDs, there are two sets of bare copper; one that is connected to 12V and one that is connected to ground. Leds are grouped based on their voltages; green and blue run in groups of 2 while reds run in groups of 4. At this point I realized that my ski poles had 9 leds which means that I had two groups of 4 and one individual LED, which was a pain. Each group has the appropriate resistor to set brightness. There are 70-odd LEDs in this frame, so figure something near to 200 solder joints.

Here’s a picture of the workbench mess:

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That’s not that bad except there is more mess here:

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and here:

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To waterproof all the wiring, I took the penguins outside and hit them very heavily with clear acrylic spray. I’ll know how well that worked when I take them down:

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Here’s a view of them drying. They have waterproof power connectors attached and have frame numbers marked on them.

And then they were each mounted on short pieces of 2×3 wood which would have been painted if I had time; maybe I’ll do that when I pull them down after they have dried out. You can see the wiring quite well in this shot, and we can see that it’s frame “J”, or the 10th frame.

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The next step was to build the wiring harness. I did a diagram of the expected layout in Visio:

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From that, I went out into my driveway, took a couple of tape measures, and laid out what I needed. The controller was planned to be under the roof where “K” is, so I would run wire to that point and then leave an extra 10’. I unfortunately don’t have any pictures of this process; I was racing the weather.

Basically, I would start at “A” in the diagram, leave a couple of feet of slack cable, run it up to D, across the top, and then down to K and leave 10’ at that end. Each cable gets an adhesive label with the circuit letter at each end, and those will later be covered with clear packing tape to waterproof them. Continue the process with each cable all the way through K. The cable is 22-gauge alarm cable; I have used twinlead in the past and I have to say that this cable was a huge upgrade in terms of ease of use, and at $31 for 500’ is was pretty cheap. I did calculations on the voltage drop and decided that it wasn’t too bad (about 7% IIRC).

Once I had all the cables, they got bunded together with wire ties at every branching location and then additional wire ties to make the harness easy to handle. I got it all done just as the rain came down for real, and headed inside. Each penguin location got the other half of the waterproof connector soldered on and then covered in heatshrink tubuing, and the controller ends got stripped to be connected to the controller. Here’s the final roof harness:

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The penguins got installed on the roof with various arrangements of wood to support them and were plugged into the harness. I then spent a day or two figuring out how to do the penguins in front of the house; they are supported on 1/2” metal EMT tubing. I also created a separate harness for those penguins (one in the air, one crashed in the tree, and then a small one where the one in the tree lost his poles and skis) using the same process.

I finished building the controller:

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Nearest to us is the ESP32 controller board that runs the animation software, and behind it are two custom 8-channel MOSFET switching boards. Attached to the back MOSFET board is a series of LEDs used for debugging.

The ESP runs custom software that drives the ESP32’s 16-channel PWM hardware. The ESP32 is ridiculously full-featured for the price. One of my goals for the project was to *not* have to pull the controllers out of their installed location to update the animation, so I created a really rudimentary web-based IDE and an animation language:

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This is the current active view from the ESP running the penguins as I sit here and write. The left textbox shows the code and the right one shows errors if there are any. I wrote the animation outline and programmed it in, and then took my laptop to the garage and we’d watch the animation and I’d tweak it as necessary, it took us about 10 minutes to get what we wanted, and I would have spent more than that on a single iteration of “unplug the controller, take it downstairs, plug it in, modify the software, compile it, upload a new version, take it outside, plug it back in, and see if it worked”. That worked very well.

I’m calling the language “Dim”, because it’s good at dimming things and not very smart. In the code “DI” means drive a specific channel to a specific brightness over a specific cycle count (each cycle is about 10mS, so it runs at 100 Hz), and D lets you specify more than one operation to occur at once during the following “A” (animate) command. The language does have for loops but is desperately in need of functions/methods for this usage; I have those in a newer version.

Here’s a bit of code running on a second instance of the controller that flashes 5 of the ornaments I make in a random pattern:

channel=2
FOR count 1:100
   D(50, channel, 0)
   channel=R(1:6)
   DI(30, channel, 1)
ENDFOR  
      

That took about 5 minutes to write.

Finally, here’s a daytime tour of the installation which shows the penguins mounted on the roof and in front of the garage and the controller board with terminal strips.



New kit: LED Candy Cane part 1

My first kit – the Dodecahedral Light Engine – has been selling about as well as I expected a very hard to construct project with limited usages to sell, which is not very well. I primarily did it because I was going to do them anyway for my decoration project and wanted a project I could learn on.

I’ve just started working on my second kit, which is going to be a lot easier to build, cheaper, and more widely useful.

One of my favorite displays is a “tree of lights”, which is a tree with custom LED ornaments on it:

The ornaments are made of small sheets of plexiglass with high-power LEDs inserted into the holes, wired up, and waterproofed.

They are really bright; note in the photo that all of the dim lights are normal brightness LEDs, and even at that level the ornaments overpower the camera sensor. They are bright enough that – and I am not making this up – they cast a shadow about 50 feet away when they were at full brightness, so I dialed them back a little in brightness.

These ones are driven directly from 120VAC as that is what the controller provides.

What I want from this project.

  1. A fun, easy-to-assembly ornament
  2. The ability to run off of 5V or 12V (*maybe* 120VAC with a big disclaimer that you shouldn’t really do it)
  3. Tunable brightness
  4. The ability to drive them as WS2811 nodes (see my WS2811 expander posts…)
  5. A frame/armature that is easy to produce automatically (the originals were done with a 5mm end mill in a drill press and took a *long* time).



Candle lantern design thoughts…

I’ve been spending some time doing a design in Fusion 360 for a laser-cuttable lantern, and I’ve discovered a few things. I’m recording them here to help others and to remind myself when I come back to this in a few months/years.

I started with a simple outline drawing of a tree that I wanted to use as the inset for the side panels:

Alder

I need to get that into Fusion in a way that works. Here’s what I came up with

From 2d to 3d

There are a couple of different approaches to doing this. If you have something that is simple, I recommend the “trace it yourself method”. In this, you insert the picture into Fusion as a Canvas (Insert->Attached Canvas), and then draw an outline in a sketch using it as a guide. I used splines and did a reindeer and rabbit outline pretty quickly, and then nice part is that manipulating the splines after that is simple and quick.

That was going to be a ton of work with the branches and I was both lazy and worried that it would be too complex to work well. So I took the alternate approach:

  1. Load the image into Inkscape and save it as an SVG.
  2. Use SVGtostl.com, upload the svg, and specify how thick you want it to be. You will be able to change this later though it’s a pain, so try to get close.
  3. In Fusion, in a new design, choose Insert->Insert Mesh, and choose the file.
  4. Switch from model mode to mesh mode.
  5. In the browser tree, right-click on the mesh and choose “properties”. My trees end up with 13000 facets, which is about 3 times as many facets as I wanted.
  6. Use the modify->remesh and modify->reduce options to get down the count that you want. You will probably have to experiment a bit to get it to work right. Start with Remesh, and preserve sharp edges and boundaries. You now have a mesh.
  7. Switch from mesh mode to patch mode
  8. Select the mesh in the browser
  9. Modify->mesh to brep. This is changing from the mesh representation – which you can’t really modify in Fusion – to the brep representation, which you can. This may take a while. At this point, you have both a mesh and brep version of the object in the tree. Delete the mesh version as it’s just taking up memory.
  10. If you look at the brep version, it has a ton of faces on it. This will slow things down, so it’s nice to clean up the faces. Modify->merge, choose “select chain”, and then click on one of the front faces. That should select all the faces.
  11. Click “ok. That’s going to sit and spit for quite a while, but eventually it should finish and you should just see one common face. Or maybe Fusion will hang and you’ll have to restart it.
  12. Convert the resulting body to a component, and save it.

Using the resulting design

The resulting design is very complex and will likely kill Fusion. It tried to use it to create panels for all four sides of the lantern, and that was a full failure; it would take a full 30 seconds to render.

What I ended up instead was doing the full design in Fusion without the complex branches. It looks something like this:

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I designed one side of the lantern and then used pattern on path to duplicate it around 4 sides to make sure everything worked, and then used it to cut the top and bottom for the tab holes.

Then, I took the original side that I designed, converted it to a component, and did the compositing of the side and the branches in a design that only had those parts. That worked well from a performance standpoint and since all four sides are identical, I can just cut the single one four times.

To get this to work I had to move the components so they were okay left/right, use align to move the frame so the front is coplanar to the front of the branches, and then extrude a couple tools to cut off the branches where they were too wide for the frame.

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Cutting on 2.7mm plywood (was supposed to be 3mm….) took about 5 minutes for each side, and a couple of minutes for the top and bottom.

Here’s a totally uncleaned/unsanded version. It would also look nicer if I taped the wood to protect it:

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Chemistry nameplate

A somewhat belated present for my wife – belated because my Glowforge had to go back to the shop.

I wanted to do something chemistry-related for her. In the past I’ve bought her a few items like the MadeWithMolecules jewelry, but we all know that gifts that are handmade mean oh so much more.

So, I came up with a concept; a nameplate for her office with some sort of relevant compound on it, and ideally that compound would wrap over the top of her name.

The problem is that most organic compounds were either too complex or structurally inconvenient for the layout. I settled on dopamine, which looks like this:

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Which is fairly simple, except that I wanted to show all the atoms, so it really looks something like this:

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I pulled out Visio and started playing around to see if I could get a two-dimensional representation that worked. And I did a bit of searching to find out atomic sizes and expected bond lengths, so that it could be accurate – which is a bit silly given that it pretends that atoms are round balls, but you get the idea.

Here’s what I ended up with:

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Where:

  • Green = Oxygen (oxygen cylinders are green)
  • Blue = Hydrogen (because water is blue)
  • Grey = Carbon (it would be black, but the nameplate background is black)
  • Nitrogen = Yellow (because I like yellow and it looks good against black)

The atomic sizes and bond lengths are as close as I could get them. The bond angles are also mostly right, except for the two carbon/hydrogen bonds at the top; you have to pretend those are a 3-d projection.

I did a laser test engrave of that on some cheap plexiglass, and that worked okay, so I ordered up some 1/8” cast acrylic for the final version.

Unfortunately, the acrylic I ordered had plastic film protection rather than paper protection, and that plastic melted into the acrylic when I went to etch it, so the results sucked. About this time, my Glowforge went into permanent “too cold” state, so it had to go back, and then there were the holidays…

I eventually finished the prototype and gave it to my wife, and we agreed on two things. First, it was a little too small, and second, the saturated blue I used for the hydrogen atoms was too dark. So, here’s the remake of the production version, starting with the acrylic straight off the cutter:

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One of my challenges was figuring out how to paint it; a few tests showed that a brush was too big, and even a toothpick was too big; the bonds next to the tiny hydrogen atoms are *tiny*, and it’s important not to bleed paint from one area to another. I found some acrylic paint bottles, but they still had bit tips.

Finally, I found these:

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These are syringes and tips that are sold as glue applicators. The tips are known as “Luer Lock” tips, and the twist right into the syringes. And this kit goes all the way to 25 gauge, which is *tiny*.

So, those showed up while waiting for the Glowforge, and then I had already purchased some acrylic paint from Michael’s:

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If you are using the smallest tips, it’s pretty hard to suck paint up through them, so I used a big tip, pulled some paint into the syringe, and then switched to the smaller tip. It takes very small amounts of paint to do this; I have a lot more than I need here:

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The technique is pretty simple; you put the tip into the corners and then carefully flow the paint into the corners to try to cover all of the walls in the paint, and after that you fill in the recess. I found that it made sense to work from different directions.

Partway through the name:

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Done with white (the bonds were a bitch, as I expected). This would look better but I didn’t clean the fine gauge tips well enough after the first version, so the ones I wanted to use were plugged.

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Done with paint. Those white spots are specular reflections from the track lights above my workbench

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Dry paint.

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And, finally, after the backing is removed:

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The coloring isn’t perfect; there are some spots where the black shows through, and in this light you can see the texture the laser cutter left. But overall, I think it’s pretty good, and it looks better in real life than in this shot.