Tuesday meetings often turn into training night at the Makerspace. So many members come the the weekly meeting that it can be easy to find something new to learn. Last week was no exception when Pete gave an intro to screen printing.
It seemed like a straight forward process and I would encourage people who want to try making a t-shirt to email Pete to get checked out on the machine.
After walking the class through the basics of preparing the silk with the design. Pete set up an example print and let his small class of makers give it a try.
So, the STAR TREK DOOR has been a slow, “back-burner” project for a while. Recently, I got a little time, so I sat down and figured out how to hook up the air valves to a set of relays, and control those relays with an Arduino.
Here’s a video overview of the physical doors themselves and how we plan to open and close them with air valves.
This is a joint project, working on this with my brother-in-law, Fred. The doors are between his garage and workshop. Fred has been working on the doors themselves, the wall and framing, and mechanical connections. I’ve been working on figuring out the software, controls, and electronic magic that will drive everything.
The physical doors themselves are done, except for paint. Fred has also been making a pretty neat frame for the garage side. He cut alternating widths of wood and then glued them together for the nice light-colored wood on the inset of the planks that will frame out either side of the door. A similar piece will cross the top of the door.
I got all the main components – Arduino, breadboard, relay board, 12V power fuse panel, and air valves themselves all screwed to a piece of plywood. At this point, it’s not pretty, but it is functional.
We have a nice industrial door control with OPEN/CLOSE/STOP buttons on it. Those are momentary on buttons, but through the power of the Arduino, I can make them be whatever I want. I started with a Button Tutorial, and then modified it to suit my purposes, and added a Delay(1500) command after activating the air valve. That way, the valve will stay open long enough to fully open or close the door, even if the button is just pressed for a moment.
I programmed the pin for the STOP button to test out a sequence to open the door, pause (long enough for a person to walk though,) and then close the door. It seemed to work pretty well. If the timing is wrong for the real-world application, all I have to do is simply change the delay times. (It will also need a safety. We don’t want the door closing on a person!)
At this point, the basics of the control panel are working. The STOP button is just wired up as a “stand-in” for a single button we already have installed on the garage side of the door. It’s a capacitive touch button that lights up either blue or white with internal LEDs. It’s a neat looking button, but it’s only a SINGLE button. So, it needs to have functionality to both open AND close the door. I’d also like to explore using a variable in the Arduino that states whether or not the door is open, and then changes the functionality of that button based on whether the door is open or not. The air cylinders themselves also have built-in position sensors, which would be neat to use possibly as both a safety AND a “Is the door open or not?” sensor.
Here’s a video clip showing all the components actually working together. At this point, if the panel was simply mounted above the door, and air connected between the compressor and air cylinders, we would actually have functioning doors.
I don’t like the look of how the air valves and tees are held together right now. I was able to find some not-too-expensive push connectors (similar to PEX Sharkbite style) for air, which might make it a little easier to connect all the air components and look cleaner. Once I really have everything finalized on what’s going on at the breadboard, I also need to decide if I want to pull the breadboard out and replace it with a custom circuit board. One thing I DO need is a simple way to connect the tiny pin connectors to the larger wires going to the buttons AND provide strain relief. For the moment, I just used staples to nail the 18 ga lamp cord wire to the plywood and then made the electric connection with alligator clips. What would be the BEST/CLEANEST way to do this? Some sort of small screw down terminals?
I also have a rather large fuse panel mounted on the plywood. It was free, and I already had it. It supports many separate circuits, but for this project, a single DC fuse would probably be fine. I’m also using a bit of an overkill 12V power supply. I’ll want to replace that with a simple wall-wart. Lastly, the Arduino is running from USB power. I’ll need to solder up a 12V DC barrel connector so that it can run off the same power as everything else. I think we will make a switched electric outlet, and plug the wall-wart in to that. If the system is ever not working right, just switch off the power and manually open and close the door as needed.
I’ll definitely want to hang out with the guys at the Makerspace sometime soon talking Arduino, specifically how to integrate some more sensors and get feedback used to activate the doors fully automatically.
Before #2: My front door, in need of paint, some aesthetic happiness, a fixed doorhandle, and summer. My desire to add a little decoration to the door is, in part, what led me to the Makerspace. I had an idea for panels to go on either side of the door, but no equipment for making what was in my head. When I saw that the Makerspace had cnc routers…
IN THE MIDDLE
I took photos of leaves from the oak tree in our yard:
I traced the leaves in Illustrator, and — by looking at the structure of the tree — made my initial design. I exported the file into svg (with hints from Shane), and Ed helped me use Cambam to convert the svg file into the gcode that the Mogul desires.
After generating the gcode, we cut the first panel. For me, watching the cutting was like Christmas: exciting — while for Ed, stepping me through the process, this must have been like a long slooooooooow Christmas, watching the design appear through the three passes the router bit made to cut each (complicated) path. (In truth, Ed’s patience and help were the real Christmas present for me.)
This panel was an experiment for me, to learn about how thin and delicate the connecting pieces could be in such cutting. And I learned: what you cannot see in the picture above is how two of the leaves broke off quickly.
In the next Illustrator file I made (which I then cut on the Mogul with Steve Pilon’s also very generous and patient help), the leaves overlap and made their stems thicker. You might be able to see this in the final picture below, which shows the panels painted and mounted. Merry Christmas!
This week I attempted the first test of the chocolate printer cooling system. The cooling system is intended to solidify the chocolate just after it leaves the extruder nozzle so that by the time the next layer is started it will have a solid layer to sit on. The cooling system consists of a centrifugal blower with a brushless DC motor blowing room air into a styrofoam cooler containing a block of dry ice. The air passes over the dry ice and gets chilled as the dry ice sublimates directly into very cold CO2 gas. The chilled air and CO2 mixture exit the box through a port with a hose that will ultimately blow the cold air on the chocolate. At least, that’s how it is supposed to work. It blows air at -12C as measured via a thermocouple, but unfortunately, the air exit port ices up in about 2 minutes and blocks the air flow.
There are many possible solutions. I can add a heater to the exit port to prevent formation of ice, or dry the air going into the box using a dessicant cannister or maybe just use water ice instead of dry ice if the higher temperature will still cool the chocolate adequately. Maybe using an old miniature freezer with an air hose coiled inside would do the job. It would be really interesting if I could use the waste heat from a freezer to keep the chocolate liquified and flowing. Back to the drawing board!
Recently Arduino came out with the Arduino Zero. This is a neat 48MHz ARM Cortex M0 processor on a PCB with the same pin outs as an Arduino UNO. Existing 3rd party UNO libraries are a little hit and miss because some access the underlying hardware registers of the UNO. The Zero hardware registers are completely different from UNO. Still, the basic 1st party Arduino libraries work fine and I’m sure those 3rd party libraries that were twiddling the UNO hardware registers directly will start to support the Zero over time.
Anway, my curiosity was peaked by the ARM processor for the Zero the Atmel ATSAMD21G18. It turns out that the processor has alternative packages with higher pin counts. Same silicon, just more pins. So I gave the ATSAMD21J18 a try. In order to be able to use extra pins with digitalWrite, I had to add a small amount of code to a file called variant.cpp, but once done, I had a Zero with a nice chunk of extra I/O capability.
Join us for The Greatest Show (& Tell) on Earth at Wisconsin State Faire Park September 24th & 25th, 2016. Admission is free. A joint presentation by Milwaukee Makerspace and the Betty Brinn Children's Museum.
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