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Laser Cutter Air Assist

My laser cutter has an air assist, which is really just a small air pump that runs when I am cutting or etching with the laser. The nice thing about LightBurn is that it adds the commands M106 and M107 to the start and end of each job so it will automatically trigger a pin on the Cohesion3D control board so that it can turn on and turn off the air assist.

Disclaimer: I’ve done a lot of projects using AC power controlled by relays using an Arduino or Raspberry Pi, and I’m comfortable working with 110VAC, but if you are not, I’d recommend you just get an Enclosed AC Relay System for Air Assist/ Exhaust Fans. It’s basically a power strip that can be controlled with two low voltage wires. Quick, easy, and safe.

Onto the project! Above you’ll see two parts loaded into LightBurn ready to cut. I tend to design my own enclosures rather than use any of the online generators, because I’m weird like that, and I enjoy it. You’ll notice the small part is only one piece, so I cut four of them, and they go on the sides. The top piece (to hold the outlet) I just cut another one, without the red parts getting cut, and I’ve got the bottom.

Hey look! All the parts cut from 3mm Baltic birch. Besides the holes for the AC socket I didn’t bother to add any other holes for wires, etc… I’ll just knock those out a with drill and/or file.

But first, we gotta glue things up… and to hold things together, why bother with clamps if I can just tape it up. (Rubber bands would also work. This is small, thin, lightweight wood.)

Basically, add glue… let that glue dry, add more glue. It’s just got to hold together when it’s all done…

Jam the electronics in there. The socket gets held in like a socket does, thanks to the holes on the top. For the relay board I typically use #4 screws to screw it down, though 3mm is a little thin, so I just glued a piece of scrap 3mm in place so I could screw into it and into the top piece a bit if needed… Oh look, I did add some corner supports.

You’ll also notice the wires leading into the enclosure. I probably just drilled holes and ran a round file across them until the wires seemed to fit so I could put the bottom piece on. Quick… and… Dirty!

Boom. Don’t even bother with screws or magnets or other fasteners for this thing… just add some black gaff tape to hold the bottom in place and we’re good.

Wires? Yeah, there’s a bunch of Dupont connectors going to the relay board. We need 5V, GND, and Signal. Simple. That’s all you need to trigger the relay. No microcontroller needed. The Dupont connectors plug into another set of Dupont connectors to change the gender (because I couldn’t find the right kind) and then into some Wago connectors. (Those things are nice!) From there I think I cut up and old 4 wire phone cable. Snip goes the RJ11 connectors!

Here’s the top, it looks not completely terrible, and prevents me from shocking myself with 110VAC, so that’s good.

Hey look, it works! You’ll see a weird switch on the top that the air assist pump plugs into. It’s just an illuminated on/off socket switch I had in the shop and used to confirm that the thing worked properly. I’ve probably removed it by now and put it on my workbench where it’s buried under three other unfinished projects.

Also worth noting: Laser cutting things for your laser cutter is akin to 3D printing things for your 3D printer.

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FSL Focus Device

I designed and printed a simple focusing device for my Full Spectrum MLE-40 4th Gen Hobby Laser Cutter. You can find it at FSL Focus Device on PrusaPrinters.org

The manual for the laser cutter shows a focus device cut from 3mm acrylic, which I originally used, but a thin piece of plastic isn’t really easy to stand up at 90 degrees properly (and won’t stand up on its own) so you couldn’t really tell if the focus was correct.

So instead I designed a triangular piece that could stand at 90 degrees much more easily. I chose a triangular shape rather than cylindrical or a rectangular cuboid so that I could easily slide one point of the triangular shape under the lip of the laser head.

Right now when it’s not in use it is stuck to the top of the laser cutter using some tape, but I’ve considered making a new version with embedded magnets so I can ditch the tape and stick it anywhere to the body of the machine.

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STL to SVG

Sometimes I need a 2D vector version of something that is a 3D model. Here’s how I do it. First, if there is an STL file, I load that into OpenSCAD.

For this model I wanted a top view so I could use the hole pattern to laser cut a mounting plate.

I select Show Axes because I’m gonna need that later…

The axes will show the center of the canvas, and luckily our model is centered…

Change the view from Perspective to Orthogonal

If you don’t know the difference between perspective view and orthogonal view, do some research I guess. (I probably learned about them in 7th grade drafting class.) Otherwise, switch between the views and it should make sense…

Okay, next I view the object from the front. Looks good!

I then add the translate command so that I can move the object in 3D space, and I lower it down, in this case 10mm, because the center line is where it will be cut.

The line projection(cut=true) then cuts a slice at the zero point in the Z axis… But we’re not done yet.

(Oh, if you choose cut=false you’ll just get the whole object, not a slice at a specific cross section of it.)

Here we can see what it looks like at an angle, which might make a bit more sense…

Let’s switch from orthogonal back to perspective view… Not required, but I’ll do it anyway.

Back to the top view… and now with the projection you can see the slice we took from the 3D model.

The next step is important… we need to Render the file! You can’t export the SVG file until you render your model.

The model will change… in this case you can see the shapes are now green with red outlines.

And now we can Export as SVG. (You could also use DXF if you need to, though that’s a garbage format I tend to avoid.)

Here’s the SVG open in Inkscape. Brilliant! I can now add to it, and my hole pattern is spaced properly for the mount I want to make. Excellent.

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Blinking Ambulance Paper Craft

I’ve been cranking out projects for Brown Dog Gadgets recently. Mostly paper craft things (that light up using conductive Maker Tape) or LEGO based things that use Crazy Circuits. Some projects area really quick and easy, and pretty fun.

Here’s an ambulance that uses two 10mm LEDs with the Crazy Circuits Blink/Fade Board to alternately blink on and off. (Josh calls this “Ambulance Mode”).

The original ambulance I started with can be found on SVGRepo. It was published with a CC0 license, so I was able to modify it and use it, which is awesome. We provide all sorts of templates and files for people to download and print on the Brown Dog Gadgets Dozuki site.

You can grab the Blinking Ambulance and follow the guide to make your own. If you don’t want to source your own components, the Brown Dog Gadgets Shop has everything you need.

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Arduino Class Files

I finally got around to publishing the files for the Beginner Arduino Class I used to teach.

Here’s some text from the README:

In 2016 I taught a classed titled Electronics & Sculpture in the Peck School of the Arts at the University of Wisconsin Milwaukee. I often referred to the class as “Arduino for Artists”.

Basically, it was teaching art students, some of whom never programmed or wrote any code, how to activate their art using the Arduino platform.

We had five concepts we wanted to cover:

  1. Digital Input
  2. Digital Output
  3. Analog Input
  4. Analog Output (PWM)
  5. Serial Communications

In 2017 I moved on to teaching the class at Milwaukee Makerspace and I refined the curriculum a bit to resemble very closely what you’ll see in these files. I used components I had available. (Note: I should add a parts list at some point).

In 2018 I started teaching the class at Brinn Labs, usually with the help of Becky Yoshikane (friend, former coworker, former student, and former classmate). We taught the class all through 2018 and a few times in 2019.

I no longer teach the Beginner Arduino Class, but I wanted to share the files in case anyone else could find them useful.

Each lesson contains an Arduino sketch and a wiring diagram (as a Fritzing file, and a PNG file). In some cases there are also images showing components, and most of the sketches should have links to the concepts/functions used in the sketch.

So there you go. If you find any of this useful, let me know. I wish I was in a position to keep teaching the class, as I really enjoyed doing so, but it’s not something I can do right now, but maybe you can. Let’s keep trying to teach electronics and prototyping to people and see what happens!