Here's another little project that I completed. I've always been interested in animatronics and found this course at the Stan Winston School. It combines some interesting animatronics with 3D printing. That last bit was the big draw for me because I've got limited fabrication capabilities but do have a workable 3D printer.
Overall, the project went well and I learned a great deal. Some of the info in the course video was out of date, so there were some challenges in finding replacements. Here are just a few:
- The recommended CAD software was not available and the slightly higher version was not easy to use. Instead I got a student copy of Audodesk Fusion 360 (yay for being in a master's program.) Although it took a little getting used to, it ended up being perfect for the project. I had tried Google SketchUp but there were too many issues (like, how do you draw two concentric circles?) I've used OpenSCAD in the past, so CSG (Constructive Solid Geometry) is very familiar -- it's just a different interface.
- A number of the parts are no longer made. There were some linkages that were from an obsolete helicopter model. I bought a couple of them off of the 'net, but as far as I know, those were the very last ones. It turned out that there were some problems attaching them to the servos that I chose, so I ended up with a different set of linkages in any case.
- The project calls for some cable tubing -- again, this was hard to find without the cable inside and I didn't need that. Thinking about it, the cable tubing was just about the same as the PTFE tubing used in 3D printers. The 3D printers use a 2mm ID but the tubing is easily available in 1mm ID, so that's what I used.
- The recommended servos are very expensive ($50 each, meaning a $300 project right there.) I found some smaller servos from Pololu that seem to do the job. They have plastic gears rather than metal, meaning that they're less reliable but this is a hobby project, not a production animatronic.
- The recommended setup is for remote controlled puppetry. Besides being expensive ($700 controller), I'm more interested in programmed animatronics. I got a USB-connected driver from Pololu and ran it from their software. I have a demo of Visual Show Animation which I'll use to drive this when I come back to the project.
- One piece of good news: The brass balls used as pivots were very easy to find, despite what the instructor said. A quick search on Amazon found them. They need a bit of polishing to be really useful, but they're fine as-is for an initial pass.
- Another bit of good news: I found some excellent irises to use for the eyes by searching for steampunk/doll parts on Etsy.
Design and fabrication of the parts was fairly easy. I prefer to work with metric parts (having a good collection of metric cap screws and related hardware) so I converted the project to metric. (As an aside, there's a great source of metric fasteners at Mr. Metric -- they sell in small quantities, making them ideal for hobby work.) The course doesn't talk much about designing for 3D fabrication and so I had to tweak some of the parts to get them to build properly. One of the big problems that I had was trying to cut threads in the parts. I'm using PLA and it's just a little too soft to do reliably. If I redo this, I'll try ABS or PETG. ABS is problematic because I don't have great ventilation in my workspace. In any case, I was able to get the threading to work in most situations and just resorted to some cyanoacrylate glue to fix problem spots.
My one significant failure was trying to power this thing. The servos can't run off of the USB power from the computer so they need a separate supply. I got a small battery pack that worked fine, but I had wanted to make it work from a wall-wart. For some reason, the Pololu power regulator couldn't deliver enough current to move the servos. I stayed with the battery pack but will have to revisit this in the future.
This is a short video that I took of the finished project.
Zane and I have been talking about turning this into an art installation, with mouths as well. Zane does great masks so we can put faces on the animatronics.