The improved second generation magnetic pendulum calligrapher with electronic remote-control brush.
After having so much fun with the v1 version of the “drawing pendulum”, I decided to improve and build “Magnetic Pendulum Calligrapher v2” by adding a RC car servo with controller for about $80, and re-configuring the pendulum construction and hinge.
The final construction and prep looked like this:
The pendulum uses a 1.2m solid wood rod. I’ve experimented initially with a suspension made from a bunch of hooks, but settled on a more flexible suspension made from fishing gear so it can rotate when needed.
It is one of these physical facts that are omitted from the computer simulation. The magnets have a physical extend, and this causes the pendulum bar to “roll” around its axis in certain configurations.
The final constructions looks like this – all the mechanics are simply taped or glued to the rod, and the brush is guided by a plastic tube (a re-purposed toy flute).
The micro servo could move the brush very accurately and fast up and down:
I think it worked very well – with the exception of the spinning motion the head tends to develop (see video linked below) since it is not symmetric in weight at all. Still, I was able to write something that resembles Chinese characters.
I’ll probably need to set it up somewhere other than the garage, and practice my drawing skills.
A 3min video of the v2 pendulum in action is here:
- the servo control and the solid pendulum rod was the key to get the drawing mechanism working well
- it is a lot of fun to draw with this contraption; I got better over time controlling the machine
- it is very easy and relatively cheap to build something that is usable for experimentation (total cost so far about $160)
- it is hard to build something that works really well (i.e. an even bigger pendulum that generates smooth stable motion and has accurate brush controls, and also looks good) – great extended project again, as long as one has a workshop and some resources to play with!
- placing the magnets as indicated in the diagram did not always generate the strokes needed for the characters – I have a feeling that one may need to place the magnets in quite different locations (maybe the spaces between strokes) or experiment also with smaller magnets or reverse polarity (repulsive force).
- I have no idea what it is “writing” … probably not Chinese! 😉
A better v3 pendulum construction would combine the v1 and v2 designs: same pendulum construction with a swivel at the top (v2), but using a solid tube to guide the brush (v1). With the brush centered into the solid tube, rotations of the pendulum would not show up much in the drawings.