It’s been an incredibly exciting week for us. The money from the Kickstarter campaign has arrived and we’ve been placing orders for parts like crazy. I’m proud to say that after less than a week we have confirmed orders for a little over 85% of the parts and we are a wire transfer or an insurance policy away from the rest. With the holidays looming, time was of the essence and it was critical that we get these orders placed fast. Ordering thousands of individual parts from suppliers around the world is a huge task, and took months of preparation. This week we’re going to show you what that process is like.
Everything starts local with a prototype built from a combination of salvaged parts, pieces from the local hardware store and parts built by hand. The next step is to find sources for these parts which can provide us with the thousands of pieces we need. For some components like electrical components this was a relatively easy task because suppliers like DigiKey are able to provide one resistor or one million resistors easily. For other parts like the custom made wires which connect the motors to the controller this can be a longer and more involved process.
Let’s walk through a couple key components of the machine and what went into sourcing them.
First, let’s talk about the wires which connect the motors to the controller board. The original blue and white wires which you may have caught a glimpse of in the Kickstarter video were made from a cut up lamp cord and a cut up piece of ethernet cable which is about as far from ready for production as you can be.
To take that wire from a functional prototype to something I am proud to send out took four iterations, with each iteration taking about two weeks to test, improve, send out improved specifications and then receive the new version. The design progressed from left to right. Wire #1 on the left worked, but the connectors were not of the highest quality. Wire #2 uses high quality connectors. Wire #3 adds color coding to make the machine easier to modify or debug, and also rotates one of the connectors 180 degrees. Rotating one connector means that both ends of the wire are identical, simplifying the assembly instructions because there is no longer a particular end for the motor and a particular end for the controller. Finally, wire number four adds a very sleek looking nylon cover held in place with heat shrink tube to prevent the individual strands from becoming tangled or getting caught.
When choosing components for the machine I took care to use the most standard parts available so that they would be easy to replace or modify, however even among “standard” parts like #25 roller chain there can be quite a bit of variation from one manufacturer to the next. We sampled each part from a range of suppliers and chose the highest quality part.
Shown in the photo below are two links of roller chain from different sources, as viewed through a microscope. Note the thicker walls, and cleaner edges of the chain on the left. We chose the chain on the left because it is made from the highest grade of steel and is manufactured to tighter tolerances.
Backers will receive only the higher quality chain, but when holding both at the same time there is a noticeable heft and feeling of quality to the one on the left, while the one on the right feels a little cheap. Either chain could work but the higher quality chain will wear better, stretch less, and the metal will corrode less easily.
The 12 volt power supply is another example of a component where there are a lot of options which could work, but we took the time to chose one which will hopefully be enjoyable to use. Build quality varies widely between suppliers. Shown here is the soldering work from a PCB inside the power supply. The soldering from the power supply we have chosen is shown on the top, and another one we tried out is shown below for comparison.
Again both power supplies powered the machine, but I believe that higher quality will last longer and be more reliable in the long run. In addition to build quality there were a number of other features which went into the power supply choice including being free of lead or other harmful chemicals, using a standard computer power cord, using a standard 5.5mm 12 volt connector, and having over-current and over-voltage protection which automatically resets so there are no fuses to worry about.
Thanks for reading, we hope this was insightful and we'll see you next week!
-Bar, Hannah, and Tom