We love a good pen plotter

BrachioGraph touts itself as the cheapest, simplest possible pen plotter, so, obviously, we were keen to find out more. Because, if there’s one thing we like about our community, it’s your ability to recreate large, expensive pieces of tech with a few cheap components and, of course, a Raspberry Pi.

So, does BrachioGraph have what it takes? Let’s find out.

Raspberry Pi pen plotter

The project ingredients list calls for two sticks or pieces of stiff card and, right off the bat, we’re already impressed with the household item ingenuity that had gone into building BrachioGraph. It’s always fun to see Popsicle sticks used in tech projects, and we reckon that a couple of emery boards would also do the job  although a robot with add-on nail files sounds a little too Simone Giertz, if you ask us. Simone, if you’re reading this…

You’ll also need a pencil or ballpoint pen, a peg, three servomotors, and a $5 Raspberry Pi Zero. That’s it. They weren’t joking when they said this plotter was simple.

The plotter runs on a Python script, and all the code for the project has been supplied for free. You can find it all on the BrachioGraph website, here.

We’ll be trying out the plotter for ourselves here at Pi Towers, and we’d love to see if any of you give it a go, so let us know in the comments.



Dougie Lawson avatar

Got to love a plotter made from clothes pegs and lolly sticks.

Shannon avatar

Okay, for a Simone robot, I just have this image of the pen being replaced with a scrub brush, and her using it to clean the tile in her bathroom or something. Maybe clean her kitchen counters. Something with less delicate and deliberate motion.

This is actually a really awesome class or club type activity. I’m really inspired by it.

Neil avatar

Beautifully simple and functional. Add a third angular degree of freedom and you could get straight into the intricacies of motion planning

joan avatar

That looked so good I just has to make one.

It works great.

I was wondering what was wrong until I found out to reverse my servo set up, bg=BrachioGraph(7.25, 8.75, servo_1_degree_ms=-10, servo_2_degree_ms=10,bounds=(-7, 4, 7, 12)).

Now I’m busy finding suitable photos of friends for the perfect portrait.

Jean-Claude F. avatar

Me too, I had to build one and it also took me some time before I realised that one servo turned into the wrong direction.

Jean-Claude F. avatar

I just wondered if I should program a GUI for linedraw (or is anything like this already existing?)
Anyone interested?

person name avatar


I spent a few hours trying to install brachiograph but I lack linux skills

Matthew Reed avatar

I’d really love to see a video of this! ? ? ☕

Thomas avatar

Hey, I build now one with inner_arm length of 29.9 cm and outer_arm length of 29.8 cm … mechanic seems to work fine … however, I have still problems to draw a correct box…seems as I do something wrong with the bounds setup…anybody an idea on how adjust this best? … bounds=(?, ?, ?, ?))

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