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DIY DSN with Screenly OSE

DIY DSN Screenly OSE

One of the nice things about doing an annual event year after year is that you can come up with ideas and even if you can’t really execute them in time you’ll hopefully have another chance a year later. So it was for my Do It Yourself Distributed Signage Network. (DIY DSN for short.)

Back in 2017 when one of the volunteers was building out the WiFi network for Maker Faire Milwaukee I came up with the idea of using a bunch of Raspberry Pi computers connected to TVs and other screens to provide real-time updatable digital signs around the venue. I’d used Screenly OSE in the past for MMPIS and other things so it seemed like the perfect solution.

If you’ve never used (or heard of) Screenly Open Source Edition before it’s a piece of software that runs on a Raspberry Pi and allows you to use a web browser to upload content to it (images and videos) and also have it load pages from the Internet.

Screenly also allows you to schedule start and stop times for content, so it’s easy to have something display between 9am and 1pm on Saturday, then disappear. For events this means you can have “live” signage for speakers or workshops as they are happening, then disappear and be replaced by a schedule or something else when done.

We managed to scrounge up eight TVs (or computer monitors with HDMI/DVI inputs) of various sizes along with eight Raspberry Pi boards. A few of the Pi boards did not have built-in WiFi so a cheap USB WiFi dongle was used to get them online. Each Pi got added to the WiFi network, got a unique IP address, and then a name so we knew where it was in the venue. Some were in front of stages, or at specific entrances, etc. Then it was a matter of creating targeted content. Most of the content was 1920×1080 graphics. (There’s a whole bunch below!)

Thanking sponsors is a great thing to do… You can schedule slides to show up for X number of seconds as well as during specific days/times or all the time.

You want to show what happens in a specific place on Saturday only on Saturday and not on Sunday? Easy!

You want to show what happens in a specific place on Sunday only on Sunday and not on Saturday? Easy!

If you can design a PowerPoint or Keynote slide, you can probably figured out how to export it to a graphic image file suitable for loading into Screenly.

Yeah, thank those sponsors! You can have a different slide for each sponsorship level, and use logos or text or whatever your sponsorship commitment promises. (Also, let your sponsors know that they’ll also be recognized on digital signage at the event!)

Presenting Sponsor? They can have their own slide! Maybe it’s on the screen for 20 seconds instead of 10 seconds… Easy to do.

We’ve done this twice now, and while it was a bit of a scramble pulling together eight Raspberry Pi boards (and WiFi dongles for some of them), eight screens (TVs 27″ or larger work best), eight TV stands or table or whatever you’ll use to put them in places, eight HDMI cables, eight SD cards, eight power supplies, etc… If it’s for an event you might be able to borrow all the hardware you need, and since the software is open source it’s mainly a matter of learning how to use it and getting familiar with it. I’d recommend getting it up and running before your event starts just so you aren’t jumping in blind trying to figure it out while also running an event. :)

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Laser Cutter Exhaust

laser-cutter-exhaust

Someone on the Milwaukee Makerspace mailing list posted an email with the subject line Laser cutter expert, so I could not ignore it. The person was specifically asking about exhaust systems. Above is a photo of what I built for the 40 watt laser cutter in my basement, and below is most of my reply.

laser-stock-exhaust

The exhaust from my laser cutter is a 4″ diameter vent hose, which I connect to a 6″ hose with an adapter I got from Home Depot. (In this photo you can sort of see the while plastic piece that attaches to the back of the laser cutter. It has a small and inadequate fan that came with it.)

laser-inline-fan

The vent hose coming out the back of the laser cutter connects to an inline fan that is mounted to the ceiling…

laser-exhaust-coupler

The output of the inline fan goes to another step down adapter and then a quick connector that twists to lock into place.

I’ve also got an AC Variable Voltage Converter which allows me to run the blower at lower speeds if desired. (I sometimes dial down for paper, thinner material, etc. to reduce suction and noise.)

laser-exhaust-mounting

I then have a basement window that I replaced with a piece of wood on the outside and pink foam on the inside which has a hole in it (covered with a laser cut screen) on the outside, and on the inside the quick connect that I connect up when I use the laser cutter.

This just gets all the fumes out of the tiny room the laser cutter is in. It doesn’t scrub the air. I am not cutting for hours at a time. My main goal was to not have my spouse come home and say “why does the whole house smell like melted plastic!?” and I think I’ve achieved that goal.

Here’s the list of all the components I could remember:

Oh, and if you want to see a real laser cutter exhaust system, or at least the details of building one over many years, check out lasercutterventingsystem on the Milwaukee Makerspace wiki.

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DIY Roof Rack

roof-rack-05

I’ve come to love my Honda Element more than any previous car I’ve owned. The fact that I can pull out the back seats and use it to haul all sorts of things is awesome, but sometimes things still don’t fit, and need to go on the roof. The one advantage my Honda CR-V had was a roof rack, but luckily the Element was designed with a roof rack option in mind, and a DIY version is pretty simple.

template-01

This forum post got me started in the right direction, and gave me a template to use. There were also a few useful YouTube videos on DIY roof racks that helped a bit…

template-02

I used the PDF template to create my own template in Inkscape and then printed it on paper, which I found to be less than ideal in getting the holes precisely lined up, so I did what I often do…

template-03

I turned to 3D printing. I took the SVG file and exported it to a DXF that I could pull into OpenSCAD and extruded into a 2.5D shape. From there I printed a nice (solid) template that I could use to drill the holes for the pieces that would hold up the rack.

roof-rack-03

The parts that hold up the rack are some scrap pieces of HDPE plastic, which is very solid and resistant to wear from the elements. The template worked great (with a drill press) for making the needed holes. There’s a 6mm bolt that holds everything in place. Yeah, I ended up just using one bolt instead of three on each piece, so in the end the template didn’t matter as much.

I didn’t use stainless steel bolts, so I expect they may rust out, and I might replace them. The main reason was I bought a bunch of bolts from Bolt Depot in various lengths because I didn’t know which I would use. Now that I know the length I should probably replace them. I also used Aluminum washers which are left over from using a hole saw to drill out button holes from guitar pedal enclosures. (Long story!)

roof-rack-01

The rack itself was just some square steel tube I got from Speedy Metals. It’s 1-1/4″ SQ x 1.084″ ID x .083″ Wall, BTW. (I ended up painting the tube black with an enamel paint, which was supposed to stand up to the elements but has done a terrible job and the metal has rusted quite a bit since these photos were taken.) I’ve been told grill paint or marine paint might work better. At this point I’d need to pull everything apart and sand off the rust if I want to make things look better. (Which means I probably won’t.) The other nice thing about getting the square tube from Speed Metals was that I was able to just have them cut them to length, so I didn’t need to cut the metal precisely.

roof-rack-04

The other piece for the roof rack are the end pieces. Yes, they are green instead of orange or black, but that’s due to the filament I had loaded into the 3D printer at the time…

tube-end-01

Amazingly enough, they are printed in PLA and have held up quite well through one winter and one summer. They didn’t melt in the summer or get destroyed by the cold and wetness of winter.

tube-end-02

They are not held in place as securely as I’d like, and are easy to remove, but they’ve stayed in place without falling out for over a year now. I should really print some replacements in another color… though it does make it easy to spot my car when other orange Elements are nearby.

So how does it work? Well, it’s a roof rack, and it works fine. If anything, I’d consider raising it a bit higher, and to be honest, I think I use it a lot more frequently when I need to tie down the back window when hauling things that stick out the back, which is good enough for me. In total the cost with the square tube, hardware, and paint, was probably around $30, which is a lot cheaper than a roof rack purchased.

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PCB Milling on the Little CNC

PCB Milling

One of my goals with the Little CNC Milling Machine was to make my own PCBs. I’ve typically made my own printed circuit boards at home by etching them with chemicals, but the mill opens new opportunities to etch and drill the boards, so I gave it a shot.

I knew the basics, but did a a quick search for posts that might explain things a bit more. (I should note I planned to use Fritzing, Inkscape, MakerCam, and GrblController, all free/open source software available on multiple platforms.)

The two useful posts I found were: PCB designing and isolation milling using only free Software and Hello World, How to Mill Printed Circuit Boards (PCB).

OpenSCAM

I wasn’t really planning on documenting this in-depth, but I got a few photos and screenshots, so I’ll share what I can. I had some bits I grabbed from eBay, 0.1mm Carbide PCB Board 60 Degree V-shape Engraving Bits and 0.8mm Carbide PCB Endmill Engraving Bits (a total of 20 bits for under $10) to work with, so that’s what I used. (I may want to try some 45 degree bits and 0.6mm bits next time.)

Milling Traces

Here’s the “isolation milling” I did with the 60 degree engraving bit. Not bad! You can also see a little mark on the copper board where I homed the machine.

Yeah, I did not have double-sided tape, so I just taped the board down to my spoil board. The board wasn’t completely flat, and bowed slightly in the middle. I’ll use double-sided tape next time, which will also help with cutting the final profile of the board.

Set Home

I swapped the bit from engraving to drilling and drilled all the holes. It seemed to work well, so… yeah. (Sorry, no photos of drilling!) I then switched back to the engraving bit to (attempt) to cut out the board…

PCB Milled

It worked, but I miscalculated how deep it would need to cut, and ended up lowering the z home and re-running the job again. I might want to use a different bit next time. When I thought the board was cut out enough I pulled it off the machine.

Light Test

The board held up to the light. Oops! Well, the holes didn’t all work. They were close, but not quite all the way through. I ended up using my Tiny Drill Press to finish the holes, and it didn’t work very well as it was difficult to hit the center. Not great.

I also didn’t cut all the way through with the outside profile. Not a big deal for this board, as it would be easy to cut out on the band saw, but more complex boards may not have this luxury. No matter, the amount of board left was paper thin and it came right out. I’ll definitely use a different bit for the final cut next time.

Final PCB

Here’s the final board. It totally worked, but there’s plenty of room for improvement. This probably won’t be the method I use for all my boards. OSH Park does a great job and prototyping PCBs, and Seeed Studio is great for production runs, but I’ll probably mill any new boards I want to test out before sending out to a fab house. Milling also allows me to have a PCB in an hour or so, versus waiting a few weeks.

Of course I’m (sort of) limited to single sided boards, but most of my PCBs are pretty simple, so I’m not concerned yet. Also, once I master the single sided board, I’ll certainly try a two-sided board, I mean… how hard could it be!?

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Little CNC Milling Machine (Part II)

CNC Machine

Hopefully you’ve read Little CNC Milling Machine (Part I) in which I completed the mechanical build of a tiny CNC machine. Here’s Part II!

CNC Machine Electronics

The electronics didn’t take much time at all, it was pretty much “plug and play” as far as connecting the three stepper motors and the spindle. No stripping, cutting or crimping wires. The only issue I had was once I tried running it nothing was happening. Turns out the power supply was DOA. I found a 16 volt laptop power supply in my junk bin and tried that, and it still didn’t work (or so I thought.) I ended up cutting the barrel jack off that power supply and putting it on a 24 volt supply I found. It was then I realized that the spindle wasn’t responding because I never set the “spindle speed”. So yeah, steppers worked fine with the 16 volt power supply (but not the original 24 volt supply I got) but the spindle didn’t go, because I’m a fool. All good now! I’ve got functioning 24 volt power supply and a functioning CNC machine.

CNC Machine Electronics

I’ve used Grbl before, usually with an Arduino and a CNC Shield with some steppers. Some of these kits seem to use an Arduino Nano, but this one is its own board with an ATmega328P and a CH340 chip. So yeah, an Arduino with Grbl 0.9 pre-loaded.

There are no endstops, but it looks like there’s room on the board to add them in the future. I can think of a few other improvements as well. I may add an e-stop, or just an “on/off” switch for the power supply. One nice thing about these machines is that if you make a mistake, like jogging the head too far in one direction, you can just cut power to the motors and the software will keep going, assuming the motors are moving, and then once the software is done, you can resupply power and try again.

Oh, you might also notice that next to the spindle connector on the board is a spot to plug in the laser. Yes, there’s also a 500mw laser that can be put in place of the spindle. I’ve not really tried that yet, and have to figure out the software to control it first. (I’ll get into software in a future post.)

CNC Machine Bed

Another area that could use some improvement is the bed. Attaching things with the screws meant to attach things to the Aluminum extrusion is not great. I’ll work on a better clamping system. (Maybe a 3D printed piece, not sure yet.)

You might also notice I left the lead screws hanging in mid-air. I did have a little bit of a binding issue with the x axis, so I just removed both lead screw holders. I think it’ll work fine without them, as the lead screws are not that long.

CNC Machine Collet

The machine came with two tiny collets that allow you to attach bits to the spindle shaft. It also came with super-small set screws. I’m pretty sure I’ll lose the screws, but…

M3 Set Screws

…luckily a few years ago my friends at Evil Mad Scientist Laboratories sent me a lifetime supply of M3 set screws of various sizes. I think I’m good!

CNC Machine Electronics

And yes, I did actually mill something. I’ll cover that in the next post. Overall I have to say I’ve been pleased with this machine (so far, it’s still early, obviously.) It was easy to put together and it works. Once I get things dialed in I’ll look into milling PCBs, and foam, and wax, and chocolate…

Stay Tuned!