This winter I had the idea of donating my old Cupcake CNC to the local library. Get it out of the basement, I thought. Put it where other people can use it. Find a home for all that extra 3mm filament that ain’t going in any of the printrbots.

What I didn’t realize was how many of the old machine’s quirks I had subsconsciously memorized, and just how finicky the toolchain has become in the years since I started using it. So I’ve been spending a lot of time at the library debugging, re-implementing, fixing, coaxing, undoing smart things that other people have tried to do…

Start with the tools: the only thing that will (apparently) talk to the cupcake is ReplicatorG. Because I’d have to build a machine-description file from scratch for any other host software, and bodging one together for ReplicatorG was painful enough. (Why yes, I did build my own custom geared extruder, and added a 3d-party stepper board to run it because, ages ago, I blew out one of the motor-driver chips on the extruder board that could otherwise be used for stepping.)

ReplicatorG means Skeinforge, with all of its interestingly-organized settings. And Print-O-matic, which gleefully ignores some but not all of those settings. (In particular, it ignores the temperature panel, which is probably a good thing to know before you start wondering why your hot end is extruding at ABS temperatures, no matter how many times you adjust the layer temperatures to be right for PLA.) At one point it seemed that the workflow would involve simply editing the g-code every time to get the right values.

So I got that stuff fixed, and darned if the kid I’d been teaching how to use the thing didn’t change some of the settings,  replug the USB adaptor cable into a whole different board and somehow cover the entire build surface with a thin, irregular layer of oozed PLA. Do you think perhaps I should write just a little bit in the way of documentation?

Today I go in to fix things again, and to substitute an unheated build platform covered in blue tape for the heated one. If all we’re printing is PLA it shouldn’t be a problem. Except, of course, rewriting the machine description file to compensate for the new distance between the platform and the endstop…

Oh, and did I mention that because this is a donated machine and not blessed by the IT department, it can’t thus far be connected to the library network?