Browsing posts in: Glowforge

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.



Cat bed elevation device

We have a couple of heated for out cat to hang out in, which she really likes. One of them lives in the living room near the windows, but unfortunately if she is in the bed she can’t see out the windows.

What was needed was a way to elevate her so that she could see out. Which seemed like a perfect opportunity for some CAD and CNC.

The design

I fired up Fusion 360 and started playing around. I started with the basic dimensions; the top would be 18” square (the bed is really pretty big) and it needed to be 11 inches tall. Then it was off to build the basic model.

In the past, I’ve used “through tabs” which are easy to do but not aesthetically pleasing. In this design, none of the tabs go all the way through, which makes it a lot nicer looking.

After a couple of hours I had the basic design:

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The bottom cutouts on the ends are so that there are four discrete legs for support, and the holes are to make it look a little more interesting. I played around with another slot farther up, but decided not to for reasons that will later become apparent. Note that there are no visible tabs.

Here’s the inside of one of the ends:

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This shows the cutouts that I will make for the end; there is the outline and slot that go all the way through, the recessed pockets for the tabs from the sides, and then the tabs that will go into the pockets cut into the top.

There are “dogbones” cut at the corners; these are needed so that the rectangular corner of the tab has someplace to go. This is using the new “minimal dogbone” add-in for Fusion 360, which is a great improvement over the previous version.

Material

I went to my lumberyard (Dunn Lumber) and procured a sheet of 12mm baltic birch plywood for $30. It comes in an exceedingly inconvenient 5’x5’ size, which means that I cannot fit it in the back of my pickup. I can, however, tie it to the top of my outback.

Cutting

I trimmed the 5×5 sheet into a 2×5 sheet for this project and a 3×5 sheet for later projects, and then set up my workspace. It’s a melamine shelf with some thin sacrificial sheets of 1/8” MDF on top and then the actual wood clamped on top.

Shaper suggests that you use double-sided tape to hold the wood down, which is a really good idea that I keep forgetting to do. I added the domino tape so the shaper can figure out where it is, and started cutting.

It takes multiple passes to go through 12mm stock, and after a few options I settled on 5mm, 10mm (the depth of the pockets), and 12.3 mm to cut through.

Here’s a shot partway through the cutting:

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I took that picture because the Shaper crashed in the middle of the cut. It luckily remembers the layout so you can keep cutting when you startup, but you sometimes lose tracking before it finishes retracting the bit so there are small mistakes in the cuts.

I had about 8 crashes while cutting the parts for this. Unlike previous projects – where it would crash only while cutting and in reproducible situations – these crashes seemed to be much more random. I’m working with Shaper on it but haven’t figured anything out yet; in this case it cut flawlessly for about 45 minutes before any issues showed up, so I suspect it’s heat related.

Anyway, eventually the last part was cut, and I could fit the pieces together. One of the joys of the CAD-based approach is that if you don’t make mistakes, things just fit together. I used my soft-blow hammer and ended up with this:

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Definitely looks like a stool. You can still see a lot of fuzz that needs to be cleaned up and an overall sanding is in order.

It was at this point I realized that I messed and hid the nice surface of the plywood up instead of down, which means the display faces have a number of patches that should have been on the inside.

Sigh. Well, my cat won’t mind.

I spent a lot of time sanding and de-fuzzing the project, and it seemed like things were okay.

Identification

As you can see, it’s definitely a stool, but it’s not a definitely a cat stool. It needed something so that our cat would know that it was her.

After spending approximately 20 hours looking at cat drawings online, I came across a set that were very minimalist, and I picked four, two for the ends and one for each side.

Those got cleaned up an image editor and then engraved into the wood with my GlowForge. That took about 45 minutes.

Assembly

The sides were glued together, assembled temporarily into the top for alignment, and clamped until they were dry. Then this was repeated to glue the sides to the top.

Finishing

I wanted something a little more golden than the natural color, so I wanted a bit of stain. I decided to kill two birds with one stone and get a polyurethane with stain.

Bad idea. Maybe a good idea if you are spraying the finish, but applying by hand every slight difference in thickness shows up as a difference in color, and if you get any runs they look pretty bad.

Lesson learned for later. After the first coat dried, everything got sanded with steel wool to knock down the raised grain, and a second coat finished it off.

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And an action photo:

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As I have not obtained a model release from the cat I am contractually unable to show photos of her in the bed.

Shaper project is here.


DLE (Globes of Fire) Part 5 – First Board!

When a new telescope is completed, one of the big milestones is known as “first light” – the first time that the telescope is used as it is intended.

Now that I am the proud owner of a reflow oven – a modified Black & Decker toaster oven fitted with Whizoo’s Controleo3 reflow oven kit – and I have a new version of my boards back – it’s time to think about how to build these things in a reasonable way.

The plan is obviously to switch from hand-soldering to reflow. To do that, the first thing that I need is a stencil that I can use to apply solder paste. Thankfully, kicad makes this really easy; you can modify the solder pad tolerances in the program, and the pcb editor can write out SVG files (thanks to Rheingold Heavy for this post). If I have the pads, I can easily cut a stencil, likely out of mylar because it’s a bit cheaper than Kapton is.

That would give me a way to do a single board if I could hand-align it closely enough. But each of the globes needs 12 of these boards, and hand-aligning is a pain.

So… what my real plan to do is to cut holes in a piece of hardboard (or cardboard) that will hold a number of the boards (12 or 24) and then a matching stencil. If I align the stencil one, then I can put solder paste on all of them.

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So, here’s the test. I took the pad svg and the board edge svg, joined them in inkscape and then cut them on the glowforge. As you can see, the boards fit perfectly into the cutouts, and the solder pads cut correctly. Next I will need to do a better version of this, with different colors for the pads and board edge so I can turn them off and off when laser cutting. I’m also probably going to cut holes for some posts that will give me registration between the board with cutouts and the stencil.

You can also see the first two boards that ran through the reflow oven. I did the solder paste without a stencil and I also skipped baking the LEDs since they showed up in a factory-sealed pack and have been sealed since, and both boards came out fine. And a 10 minute reflow cycle is a lot quicker than hand soldering…


An inexpensive glowforge stand…

My glowforge lives in a workshop I have that I’ve been working on fixing up. The workshop was bare studs but now it has plywood walls and some improved electrical.

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As you can see, it’s sitting on top of some old and tired cabinets that I don’t use for storage because they don’t work very well, and a counter that sags in the middle. I need something to be better at holding both the glowforge and the other stuff I want to do down here (in particular, I need a place I can put a reflow oven for some electronics projects).

My initial thought was to price out some replacement cabinets and a countertop, but that quickly started looking like $800 – $1000 for the cheap stuff. So, what other alternatives could I use?

I was inspired by Mike’s table in this forum post:

That’s just a cheap home depot storage rack, only using part of it. I found a rack that was like it at Home Depot, and it was only $60:

But… It was only four feet wide, and I wanted some space to put my laptop and other stuff next to the glowforge. So, I started looking for racks that were wider but still 24” deep. The ones I found were a lot pricier; something like $150 or so.

Time passed, and I ended up on Costco’s website, and decided to search there.

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What have we here? 60” wide, 24” deep, and a full 72” tall. $170, so not super cheap, but pretty close to what I wanted. I could put four shelves at the bottom for flat goods, and then one shelf at the top, and the glowforge would be at waist height. And wheels if I wanted them.

It took about a week to ship, and the box it showed up in was heavy. 104 pounds heavy. I dragged it off the front porch and into the garage, opened it up, and found that it was just what I expected. 5 shelves, and – to save on shipping costs – the corner posts come as two sections that screw together. I did some measurements, and realized that if I didn’t use the casters (it comes with both casters and normal feet), the length of he bottom posts was almost exactly counter height, which meant I could do a build that was pretty much at counter height.

And… if I only used 3 shelves on that, I could use the remaining parts – the upper posts and other two shelves – and build a second countertop-height system to go next to the first:

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So, that $170 got me two counters – one to hold the glowforge, and one to hold whatever else I want to put next to it. But if you didn’t want the second counter unit, you could easily put the other two shelves on the glowforge part and get a lot of storage for flat materials. And have it on wheels if that is useful for you.

There was only one problem. Wire shelves aren’t the nicest things to put stuff on as small items fall through the openings, and you can’t write on them either. What I needed was a countertop to go on top. There are a few options:

  • Buy one of the ikea countertops – like this or this – and trim them down. I would need two in this case, and that would be another $120. Decent idea, and I like the black look. So yes for fancy, but no for this setting.
  • Buy a full sheet of melamine. My lumberyard will sell me a 48” x 96” sheet for $35, and that would do both counters with some left over. Downside is that the 1/2” sheets are about 65 pounds and a bit of a pain to transport. And the exposed edges aren’t white.
  • Buy some pre-drilled shelf panels. These are meant to be used for the sides of cabinets with shelves in them. $38 each, and I would need two of them.

I was going to go with the big sheet for $35, but then I got to looking around and remembered that we had some extra Ikea shelves hanging around. They are about 29” x 24“, so I’ll just need to trim a bit off of them to make them the right depth (if they are trimmed to 23.5” they will fit between the front and back wire sections and not slide around). When I went and did that, I found that two of the shelves are almost perfect in length between the posts, and everything looks quite tidy. Here it is.

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Plenty of space for a laptop on the right side, lots of storage for stock underneath. I might build some vertical storage on the left side; not sure yet.

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The shelf is plenty deep; I have mine towards the front to make the exhaust fit better. What I really need to do is trim a couple inches off the duct.

If you are going two countertop-high units, you’ll want to drop the first one down one inch so that everything is level. It looks like this.

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