007.1: In the Physical World

This past week has been all about trying to get a physical object into a testing state. I haven't touched the Othermill since May — nor have I created my own PCB, so it was a lot to figure out. (I did make the Hello, World project in February, so I had an idea of how it should work, but mostly just an idea.)

So Friday I spent all day making files for the new milling projects — PCB for the motor and button mount, one wax for the case + plunger, and another wax for the new object mold itself — and then Saturday in the lab milling. It has been somewhat less than a successful iteration.

The PCB

Based on my work with the Hello, World, I decided to try to use Eagle CAD to create my board. The goal was a board with space for my button and motor and pads to separate input pins and a shared ground. Pretty straightforward, I thought. Except for the part where I had never used Eagle. But I've figured out all sorts of Adobe programs and can read tutorials, so why not? The first surprise is that it is really hard to draw components in Eagle. The workflow is set up around importing components from a library of designs uploaded by manufacturers or retailers like SparkFun. It works less well when you are using random components from Amazon. But I persevered and after a few hours, I had a file ready for the Othermill!

Sadly, as I discovered Saturday, this file wouldn't work. See over on the right in the last image, how the buttons marked Traces, Holes, and Outlines are all selected? When you select only Holes, they aren't there. At first I thought it was the tool size, but even down to a 1/100th bit, there were no holes. After a little more searching and clicking, I realized drawing an SVG of what I wanted would be a lot faster. So I did that. And it worked. Too bad Othermill seem to have removed SVGs from the new version of Otherplan. Being able to just draw the line you want to cut is underrated in the pursuit of "user friendliness" and well — the internet is full of similar rants for any product you can think of.

The Wax Molds

Because I have done wax molds for the object before, I knew how to create the files to mill objects. Turns out, though, I made a few calculation mistakes along the way. For the first mold, I made the object too high and the body too low to contain the board. (I also forgot to change the default max pass depth, which led to a god two hours wondering why everything took so long.) When I ran the project a second time — with the 1/8" bit and a .05" max pass — it was a lot faster. However, when I ran the pedestal again with a 1/16" bit, to clear out some spots the 1/8 missed, I decided to add a little more depth just for fun and managed to mill all the way through. Oops. Turns out I had reset the Z once the facing finished and forgot. I filled it with silicone anyways, and now the top is drying. With luck it will be deep enough, but if not, I know what not to do when cutting again.

By contrast, milling the wax for the case and the plunger went right the first time. This should have tipped me off that something was wrong, but I wanted to believe. The main problem here revealed itself when I broke out the silicone this morning: the plunger is too close to side (and frankly, the side is kinda fat). I have to cut from the outside of the line and double check the measurements, so it looks like I'll be back in the lab this afternoon. I'd really like to have the whole bit setup for Wednesday's call, but this is pulling it a little tight.

Bonus: Bean Case

While I was subtracting away, Wes was running the additive machine to make a case for the Bean. This too turned out to be off measurementwise — the numbers were right but the ends of the Bean are not a perfect arc. Whoops. One more thing to iterate on.