Let’s say you’ve got a big bare wall in your home, and you want some art on it. You could hang a poster or a framed artwork, or you could learn to paint a mural yourself. Or, like [Nik Ivanov], you could build a plotter called Mural, and get it to draw something on the wall for you.
The build is straightforward enough. It uses a moving carriage suspended from toothed belts attached to two points up high on the wall. Stepper motors built into the carriage reel the belts in and out to move it up and down the wall, and from side to side. In this case, [Nik] selected a pair of NEMA 17 steppers to do the job. They’re commanded by a NodeMCU ESP32, paired with TMC2209 stepper motor drivers. The carriage also includes a pen lifter, which relies on a MG90s servo to lift the drawing implement away from the wall.
The build is quite capable, able to recreate SVG vector graphics quite accurately, without obvious skew or distortion. [Nik] has been using the plotter with washable Crayola markers, so he can print on the wall time and again without leaving permanent marks. It’s a great way to decorate—over and over again—on a budget. Total estimated cost is under $100, according to [Nik].
We’ve featured some neat projects along these lines before, too. Video after the break.
When I first saw a similar mechanism used for the Maslow CNC router, I started wondering how hard it would be to put an oxyacetylene torch or plasma cutter on a mechanism like this and have a really impressive steel fabrication capability with scarcely any shop room occupied by it. There is a big problem surrounding what goes behind this that doesn’t get destroyed by the shower of molten steel. But, maybe there’s a new art form to be discovered here, like Fordite but with metal spray.
It would be difficult to get reliability out of this. For example when a wire get snatched, and bends for a moment, the coordinates will be off, and that results in ruined parts. The heavy wires (hoses) on such a cutter also make it more difficult.
The thing is also unbalanced. In the assembly video below you can see @10:50 that the pen position shifts when it finds equilibrium. This balance also shifts over the working area, and this introduces distortions. Not such a big deal for “artwork”, but not good for a plasma cutter.
https://www.youtube.com/watch?v=Yg7z5wKEo0o
Also, there is not much info in the video linked to by Hackaday. (just silly sped up video, sigh). The assembly video I linked to has more info.
If you have limited space, then a plasma cutter based on a SCARA robot is one of the better options. There is a commercial plasma cutter that does this (arcdroid) and Evezor has also experimented with this. I am thinking myself of building something more similar to the “drawbot”, but make it in such a way that it can be easily (dis) assembled, and stored as just two tubes, each with it’s own motor and drive system.
Also when you are cutting the surface you now are pressed against is no longer flat. Which isn’t insurmountable, but would pose issues for deciding what order to do the cuts.
The polargraph come back ?
I think the first time I saw this style of drawing robot, it was Hektor. The archives have us posting about it in 2005, but it was already 3 years old at that point. https://juerglehni.com/works/hektor
Yeah! I think Hektor is indeed the great-grandfather of all the two-axis hanging plotbots. I’ve never found anything older. If anyone else knows any better, let us know!
Very nice design, I like it. It is an interesting idea to put the heavy stepper motors in the plotter head. But obviously it works well and reduces the installation afford.
Yes, indeed, that is a nice variant that improves upon the older designs.
The next step up is to:
1. Put both stepper motors directly under the pen.
2. Add some guide rollers, so the GT2 belt goes as close as possible towards the center of the pen.
These two optimizations reduce wobbling, distortion due to friction and other causes, and thus makes it plot more accurate.
Sometimes I wonder if this sort of plotter could be useful in schools. The Idea is to make it easy to plot drawings and graphs etc, on a whiteboard or chalk board, Maybe during a lesson, or in the breaks or during the pupils changing classes.
Like Stringent: https://www.hackster.io/fredrikstridsman/stringent-the-15-wall-plotter-d965ca
That Buford’s a sly one. He already knows his ABCs.
https://www.youtube.com/watch?v=1zJCftRSHvM
It would be interesting to give this thing a UV LED and have it draw on a glow in the dark wall or perhaps a white board with a dry wipe marker.
don’t forget the old childrens’ hospital trick, often employed by staff or students as a community project rather than a commercial service:
project your mural using either an overhead projector with outline of Mickey Mouse etc printed on acetate. These days it would be a conventional computer data projector – complete with keystone correction. Then paint the outline on the wall.
Thankfully, I cant say I spent a significant amount of time in hospital as either a patient or staff – its just something I have noticed – janky or not janky looking Mickey Mouse or Bugs Bunny in these settings.
The
Reminds me of the graffiti plotter created by Niklas Roy, and recently featured in a talk at Supercon Europe. https://www.niklasroy.com/graffomat/ Looked very cheap to build (motors were cordless drills, linear bearings were sliding conduit, etc.). The print head is one or more spray cans!
Great use of tech! Many years ago I had a similar idea for a real-time system using this technology to cut the glare from the sun in my living room. I had just bought a house in Seattle where the sun (and every photon) is sacred and didn’t want to have to draw curtains to block the sun … and the great view out of my ~30′ of west-facing windows. I created a dual stepper motor+Arduino “string puller” to move an ornamental 3′ sun-occluding paper disk in X & Y across the window to block the glare from my eyes when working at my computer, watching TV, reading etc. I use a small wireless remote to put the disk in place initially, then the motors would move the disk in-sync with the sun to give me a glare-free day, assuming I didn’t move my position in the room. My next step is including the appropriate sundial math to automatically position the occluding disk and track the sun every day :-)