Welding session

Posted on January 28, 2018

This week marks the beginning of the fabrication of the Kinetic Cabinet’s metallic frame, which will be made of three separate components: a simple frame, a bottom angle bracket onto which the motors and gears will be attached, and a top angle bracket which will serve as bridge and surface onto which the tuning keys will be attached.

I bought a 20 feet L-Bracket from Acier Lachine, which I will pick up this week. In the meantime, I welded the frame, which onto which both the top and the bottom will be attached. These three components will be bolted to each other, making them removable. I believe this may help a bit when I will bring those pieces to be chromed.

I knew this artwork was going to be big, but there is a big difference between looking at drawings and computer diagrams, and having the physical frame in hand: the frame is 61″ x 26″! Which leads me to think that the final piece may be some 64″ x 48″ x 8″… Wow!

Preparing the motors

Stepper motors come pretty bare: you get the motor and some wires coming out. It makes sense, as the makers cannot know in advance how their consumers will connect those motors. In my case, I will connect them to a small bridge. While the product image doesn’t show it, the holes are used to add male jumpers (although female jumpers could most probably also be used). So to connect to those jumpers, I had to add female jumpers to the end of my motor wires (see the images above). That was a long boring soldering session, but I now have all my 12 motors and bridges ready!

I started testing the motors connected to the Arduino Due. The examples for the AccelStepper library are rather clear on how to use multiple steppers in code. However, after a minute or two of running the motors, they start slowing down. I also had a hard time to keep the voltage steady, probably because the breadboard did not convey connections properly.

So for now, I first have to ensure I can have a steady voltage for the motors. Then, I have to figure out why the motors slow down. Although, they never will run continually, but I do want to ensure that this issue does not hide something else.

Planning the wooden body

As the metallic frame becomes more and more a reality, I am refining the design of the cabinet’s wooden body. I am trying to figure what are the electronic components necessary, and where to physically put them.

As I intend to have the power cable come from the bottom, that is where I will place the socket.

Originally I wanted to have a single power supply to power all motors and other components. However, while discussing this with Thierry Dumont, a colleague from TML, he suggested I split the design into two power supplies, so that would reduce their amperage need.

I will have holes in the top and bottom parts of the body, so that the air can circulate. Twelve motors running for a while will for sure become hot, and it’s best to allow air intake for cooling. It was suggested to me that I may want to use computer fans, however I don’t know that I want to add a noisy element to this piece, so I believe I will simply use a CNC machine to prepare holes.

I have yet to finalize the design of how to hold the windowed door and how to place the Raspberry Pi camera.