Skull Useless Machine

MakerFX attends a number of outreach events. One of the purposes of these outreach efforts is to introduce people to different things we make and do at the space. I have liked the idea of a “Useless machine” but wanted to make something more elaborate and entertaining. We came across a plastic skull that had a jaw that was already hinged and decided to create a useless machine with it. The theme is, the skull doesn’t like to be bothered and complains in an escalating way every time someone pushes the switch.

I initially used normal Arduino Uno boards but the MP3 player I was using wouldn’t multi task. This proved to be a problem since servos need to be working during the MP3s playing. I ended up using a Teensy 3.5 with the audio shield. This board is probably overkill, both in cost and horsepower, however was an easy fix to the problem. 

In the end, the system uses six small servos, two larger servos, a car power window motor to raise and lower the head, some level shifters to convert the 3.3V output of the Teensy to 5V for the servos and relays, some 5V relays to switch the 24V that is powering the car power window motor (I am driving the motor at 24V to make it go up and down faster), and a small 5V audio amplifier.

The frame is welded 1/2″ steel tubing and the outside panels were cut and engraved on one of the MakerFX lasers. The outside panels are hinged and the tops of the panels are kept in place with magnets so they can be folded down, this allows people to see how the mechanics work. There are also a few 3D printed parts; the switch lever, the bracket that allows the switch to be lowered for transport, and the eyebrows. As with most involved projects I do, it took far longer than I had originally expected!

Here is a video overview of the machine in action:

If you’re interested in learning more about how to make things, come out to MakerFX any Friday during our open make and we will gladly show you other things we are working on.