New Firepit

After 16 years or so my old firepit has finally rusted through. The legs pushed up from the bottom and it was time to say goodbye. This provided a nice opportunity for another COVID project and something to keep me busy for a while. After browsing around for a bit looking at designs I turned to fusion360 to design it up. Final design looked like this:

Was trying to make something quite stout, but still composed of straight lines for easy cutting/fabricating. As is my usual, to not-quite overkill it, but still go beyond what necessary I ordered a 4’x8′ sheet of 7 gauge steel (3/16). I ended up using about half the sheet which was $150, so the materials for the project were about $75.

Tooling on the other hand, well… I needed a saw to cut the pieces up. I love my cold cut chopsaw, and found they have circular-saw style ones for sheet goods. I picked this Milwaukee up and it is truly amazing. Its sort of freaky how you can cut steel like a sheet of plywood. Big downside is there are metal shavings EVERYWHERE in my garage. Wear your PPE with these saws. HOT SAWDUST!

In fusion360 I exported the measurements for the side pieces and the ‘feet’. I drew these out on the sheet paper I use to cover my workbench (which I love doing each time I begin a new project – fresh start!). Then I used little magnets to hold the paper down and spray painted around the edges giving me my cut lines. Used a straight-edge the guide the saw and spent a few hours cutting all the pieces out. If you want to build your own, the .pdf dimensions are here (Sides | Feet).

This would have been a quick job with a MIG welder, but all I have is a TIG, so it took a little longer. But my welds got better and I was pretty surprised at how well the fit up was. I used a construction square clamped to workbench to keep the angled sides at 90 degrees.

I did all the welding on the ‘bottom’ so when its in normal use you can’t see any of the welds. Here you can just see the tacks I did to piece it together, but I eventually ended by doing a full bead down those sides. The bottom piece I had to cut a bit with my jigsaw to get the vent holes in. It was way slower than the Milwaukee. Maybe I should have not cheaped out and just got a plasma cutter!

With a little help from the kids I got this beast off the workbench and moved into the backyard. Tonight we test drive it!

Arc Reactor

A somewhat atypical project for me as its more artistic in nature, but covid-19 lockdown is driving me to dig deeper into the project archive. I had printed out some arc reactor parts from thingiverse a while a go and they were sitting in a box as they didn’t look very interesting in their stock form. I did a little sanding/painting of the parts and decided to go for an old school Iron Man 1 made-in-a-cave look, so i used a lot of rust type colors.

This was my first time using magnet wire, and i used it both aesthetically (wrapped around the 10 nodes) as well as for actually wiring up the LED’s. If you haven’t used it, this wire is copper coated in an enamel coating to protect against short-circuiting. That means to solder it, you need to clean off the enamel, and I basically just burnt it off with the soldering iron which worked pretty well.

Conways Game of Life

Finished up the hardware to display the results of my coding exercise. My primary goal was to learn a little more about python and object oriented coding. I could never really wrap my head round objects, and I needed a project with real end goals to address that. The code is available and has documentation on github.

Basic construction is comprised of 16×16 pixel ws2812 panels in a 3×3 grid. The way the panels were laid out and wired made a sort of weird numbering scheme, which I had to compensate for in software. Next time i’d be more planful on which inputs go to which outputs.

I made a picture frame out of walnut to contain the insides. There are actually 2 panes of glass with the following layers:
Matte with display window cut
Papyrus type paper for led diffusion
The 3d-printed grid
the wooden panel with the led’s mounted
This stack keeps everything tight/contained and keeps the LED grid close agains the diffuser paper so the lines are crisp. I used the LED grid so i’d get colored squares instead of circles, to me it really looked a LOT better.

The somewhat ungainly back of the stack. I put air holes along the top as I wasn’t sure. how much heat the LED’s would generate, but they aren’t running at full brightness and the glass doesn’t even get warm to the touch. You’ll notice the 3 cross braces, which are bowed up by spacers in the middle. This presses the whole grid tightly against the glass, keeping the lines displayed bye the grid on front tight. Powered by a raspberry pi with a small level converter IC to talk 3.3v -> 5v.

Pandemic Clock

What day is it anyway? Seems like that is the running joke working from home these days. With a fair amount of idle time on my hands I thought I’d make a little clock to help out. One of the construction goals was to use parts on hand, as going out to stores wasn’t really in the cards.

Clock face is some pretty basic plywood i had on hand, with the days pocketed in with the CNC machine. I did use a 1/8″ downcut bit to not chip-out the super thin layer of good wood on the top. Next time I do something like this I’d cut through tape as it would make the next epoxy-filling step a lot easier.

The text is a 2-part 30 minute epoxy with some coloring mixed in. My son has gotten pretty good at mixing/pouring. Did our best to clean up any spillage with mineral spirits while it was still wet, and later sanded what was left with a 320grit paper. The movement is just a small hobby servo, but it only rotates about 160 degrees. I 3d printed out two gears to create a 2:1 ratio so the servo could swing pretty much the full 360 degrees to move the hands. For gear generation I used gearDXF.

The controller is a NodeMCU, which is an esp8266 dev board. These are programmed with the Arduino IDE, and controlling a servo is easy with the built in library.

Code is on github if you are interested. Here is a link to the fusion model.

Conways Game of Life Preview

Working on a new project, combining making something fun with learning some new skills. In this instance the primary goal was to learn a little more about python, Visual Studio Code + Github, and object oriented programming (my first class!).

Sneak peek below, but this will be a RGB 48*48 matrix framed in a shadow-box on the wall. Initially it’ll run the game of life, but could be updated later to display anything. Early pics of the physical project below, and link to gitHub repository.

First cuts on new CNC

Not a super exciting project, but it did let me actually make something on the new CNC. My son has been playing with epoxy and learning to make things by watching youtube. We made a table for the basement a while ago, and it needed some coasters. Pretty basic profile/pocket of our lake, and he did the epoxy fill!

CNC Upgrade :: Bed

For the bed of the machine i just used a 1/2″ steel plate. I went with hot rolled as they didn’t have cold rolled available. This was an eehhhhhh sort of choice. Its not dimensionally flat across the work area, and I really don’t have the power available to mill it directly. For the interim i attached a 1/4″ aluminum sacrificial bed on top of the plate which i could mill flat.

This gets us to the end of the physical construction. Final touch was drawer fronts, with some wrenches i got from my dad when he retired his mechanics business.

CNC Upgrade :: Electronics

This machine is based around a smoothstepper control board driving gecko stepper motor drivers. On the pc end of things gcode is processed by mach4. It’s an interesting relationship between these three companies as the lines of support are pretty gray. I had some issues during the build and its amazing how on the back-end their engineers all seem to know each other. In particular the smoothstepper guys were super helpful on some issues that wen’t pretty deep into mach4 territory.

I also just wanted to say that you’ll pay a bit more for the gecko drivers, but their support is top notch. I blew up a board due to ignorance, and they replaced it without even an admonishment!

D-rail rookie here missed that common ground bar on his second-hand components. Shorted out all the outputs from the gecko driver. Pro tip :: that lets the magic smoke out.

I did as much of the wiring on a backer-board on my workbench as I could before mounting the panel in the back of the machine. The stepper drivers need a heatsink, and I had this one in my garage for 10+ years. Originally it was going to be for a home theater amplifier.

I 3d printed up a bracket for the smoothstepper, and even printed some cable management loops. On my last build 3d printers really weren’t a thing so maybe i went overboard, but this was pretty fun. Used a lot of ferrules which I learned about volunteering at the high school for First Robotics. Nice to cross pollinate skill sets!

We bring in 220 on the left, which goes through a big contactor, with only the 5v rail-mount power supply always being powered. The contactor is initiated through a the aircraft toggle mounted on the estop box. That basically turns whole machine on/off. The limit switches on the machine were 24v so i had to solder inline resistors so they would work with the 12v inputs on the smoothstepper.

CNC Upgrade :: z-axis (part 2)

Once the fixed back plate (3/4″ aluminum) and the movable front plate (1″ aluminum) were machined it was assembly time. Here you can see the parts laid out and ready to go. In the upper-right you’ll see two white brackets to mount the stepper motor and tension the belt. These were 3-d printed with the mindset that I’ll mill aluminum ones when the machine is up and running. I found out about the option to put brass screw inserts in the 3-d print too late, but it looks like an awesome procedure and is something I’d do in the future.

Assembly was pretty straight forward. I did have a little binding on the lead screw and had to shim it out a little bit using some folded aluminum foil. Shim stock isn’t something I have on hand!

Minor shimming required where the ball screw attaches to the moveable plate.

And some additional photos of the assembly and mounting to the y-axis.

Once it was on the machine I could locate the z-axis homing switch. I used a fairly inexpensive magnetic sensor from amazon. I mounted the sensor in the back plate, and then drilled/tapped and threaded a hex-cap bolt in the movable front plate. This bolt triggers the magnetic sensor when the z-axis is in the full-up position.

CNC Upgrade :: z-axis

Pro-Tip : Just buy a z-axis. It’s likely not worth the hassle, unless you don’t value your time. Or if this really and truly a hobby and you enjoy doing and redoing things.

That said I built a z-axis! I bought a bundle of parts off ebay and used that as a ground floor for measuring and designing. Having parts on hand provided a good starting point for scale and feasibility in Fusion 360.

From there it was quite a few iterations to draw up what would become the axis. During this process I learned a LOT about fusion, as I wanted all the movements to work so I could watch for clearance issues etc. Saunders Machine Works’ youTube channel was a huge help. The final drawing (looks like 42 edits) looked something like this.

Mounting the stepper that way was a little more work, but it keeps it from sticking out the top, and counter-balances the weight a little bit. Here is a zip file with the fusion model if you want to use it.

I started doing the manufacturing of the backplate the manual way. Lobbed off a piece of 3/4″ aluminum stock and started drilling, tapping, and cutting. Fusion allows you to print out 1:1 sized prints which worked super well. I just sprayed on contact adhesive and glued the template to the stock. It was a lot of holes, and a lot of tapping.

The studious observer may notice the two pockets where the bearing-blocks for the lead screw attach. Those I didn’t get done in my garage. At the high school they have a old cnc Haas mill that we have access to for working on the robotics team. They were kind enough to let me run the pocket operations I needed on that mill. Thank goodness! It would have been nice to mill the whole piece there, including the drill holes but I didn’t want to overstay my welcome.

Quick gratuitous Video of chips flying: