4 ms·

Show HN: BrachioGraph, an easy-to-build pen-plotter, driven by Python

apankrat 7y ago
A link to the project page with HowTos won't hurt - https://www.brachiograph.art/ https://www.brachiograph.art/
DanieleProcida 7y ago
Full details of the project, including all the code and documentation, are posted at https://www.brachiograph.art https://www.brachiograph.art. This is my attempt to do something with the Raspberry Pis and cheap servo motors I've had hanging around that's both genuinely interesting and also as simple and cheap as possible. Robotics isn't my subject, but I wanted to make something. The total cost of hardware (excluding the clothes-peg, pencil and things you will find in a kitchen drawer) is €14. You could build the whole thing in about an hour, it's a fun thing to do with a child, and they love the fact that it's made from household materials. One thing I like about it is that it's all 'wrong' - you are not supposed to use servos or electronics like this, and it's not what a 'real' engineer would do - but it still works well enough to be fun. The cost and simplicity are really important because this project has come with me to events like PyCon Africa (http://pycon.africa http://pycon.africa) and PyCon Namibia (https://na.pycon.org https://na.pycon.org) where not everyone has easy access to labs and hack-spaces and electronic hobby shops, and many people have to learn and experiment on much smaller budgets. There's some custom Python code: https://github.com/evildmp/BrachioGraph https://github.com/evildmp/BrachioGraph and contributions and issue reports are welcomed. And it's on Twitter: https://twitter.com/BrachioGraph https://twitter.com/BrachioGraph. If you build one yourself, please send me a picture!
- ChuckMcM 7y ago
  This would be a better link to have the article reference.
  - dang 7y ago
    Ok, we've changed the link from https://vimeo.com/372867891 https://vimeo.com/372867891.
powerbroker 7y ago
I'm a big fan of ink, since it gives better contrast. Can the python software be adapted to not drag across freshly drawn lines? Are there pens that work better in that context? I've got some parts laying around and I just might build this. Plus, it will make my brother-in-law sad that he spent > $100 for some kind of plotter he uses on a whiteboard.
- DanieleProcida 7y ago
  It works fine with every kind of drawing implement I have tried: * pencil * charcoal * ball-point (needs additional weight on the pen) * roller-ball * felt-tip * fibre-tip It draws so slowly that there's no issue about waiting for the ink to dry. But what I like best is soft pencil on slightly textured paper. Daniele
yorwba 7y ago
Previous discussion about the documentation for this project: https://news.ycombinator.com/item?id=21281525 https://news.ycombinator.com/item?id=21281525
jmpman 7y ago
Fantastic. Thanks. This will be my next project.
jascii 7y ago
Cool project! Feature-creep: I can't help wondering if there would be ways to improve the precision enough to make for instance PCB's without increasing the complexity/cost to much..
- DanieleProcida 7y ago
  Not with these servos or this mechanical arrangement, that's for sure. But, it's very interesting to think of ways to improve the precision of imprecise hardware, using only software.
  - mmastrac 7y ago
    Could be really interesting to add cheap cameras and OpenCV to this concept!
geokon 7y ago
What are the "standard" algorithms for vectorizing bitmap lines? I'd had a little art project where I wanted to draw lines on the wall and then have them captured by a camera and vectorised .. preferrably "minimized" to be as few vectors as possible. I couldn't really design an algorithm that was satisfactory and I didn't wanna just hack it with some heuristics I see they're doing it here with an edge detector - anyone have any insight how it's done? Is this a solved problem in computer science?

A link to the project page with HowTos won't hurt - https://www.brachiograph.art/ https://www.brachiograph.art/

Full details of the project, including all the code and documentation, are posted at https://www.brachiograph.art https://www.brachiograph.art. This is my attempt to do something with the Raspberry Pis and cheap servo motors I've had hanging around that's both genuinely interesting and also as simple and cheap as possible. Robotics isn't my subject, but I wanted to make something. The total cost of hardware (excluding the clothes-peg, pencil and things you will find in a kitchen drawer) is €14. You could build the whole thing in about an hour, it's a fun thing to do with a child, and they love the fact that it's made from household materials. One thing I like about it is that it's all 'wrong' - you are not supposed to use servos or electronics like this, and it's not what a 'real' engineer would do - but it still works well enough to be fun. The cost and simplicity are really important because this project has come with me to events like PyCon Africa (http://pycon.africa http://pycon.africa) and PyCon Namibia (https://na.pycon.org https://na.pycon.org) where not everyone has easy access to labs and hack-spaces and electronic hobby shops, and many people have to learn and experiment on much smaller budgets. There's some custom Python code: https://github.com/evildmp/BrachioGraph https://github.com/evildmp/BrachioGraph and contributions and issue reports are welcomed. And it's on Twitter: https://twitter.com/BrachioGraph https://twitter.com/BrachioGraph. If you build one yourself, please send me a picture!

ChuckMcM 7y ago
This would be a better link to have the article reference.
- dang 7y ago
  Ok, we've changed the link from https://vimeo.com/372867891 https://vimeo.com/372867891.

powerbroker 7y ago

I'm a big fan of ink, since it gives better contrast. Can the python software be adapted to not drag across freshly drawn lines? Are there pens that work better in that context? I've got some parts laying around and I just might build this. Plus, it will make my brother-in-law sad that he spent > $100 for some kind of plotter he uses on a whiteboard.

DanieleProcida 7y ago
It works fine with every kind of drawing implement I have tried: * pencil * charcoal * ball-point (needs additional weight on the pen) * roller-ball * felt-tip * fibre-tip It draws so slowly that there's no issue about waiting for the ink to dry. But what I like best is soft pencil on slightly textured paper. Daniele

yorwba 7y ago

Previous discussion about the documentation for this project: https://news.ycombinator.com/item?id=21281525 https://news.ycombinator.com/item?id=21281525

jmpman 7y ago

Fantastic. Thanks. This will be my next project.

jascii 7y ago

Cool project! Feature-creep: I can't help wondering if there would be ways to improve the precision enough to make for instance PCB's without increasing the complexity/cost to much..

DanieleProcida 7y ago
Not with these servos or this mechanical arrangement, that's for sure. But, it's very interesting to think of ways to improve the precision of imprecise hardware, using only software.
- mmastrac 7y ago
  Could be really interesting to add cheap cameras and OpenCV to this concept!

geokon 7y ago

What are the "standard" algorithms for vectorizing bitmap lines? I'd had a little art project where I wanted to draw lines on the wall and then have them captured by a camera and vectorised .. preferrably "minimized" to be as few vectors as possible. I couldn't really design an algorithm that was satisfactory and I didn't wanna just hack it with some heuristics I see they're doing it here with an edge detector - anyone have any insight how it's done? Is this a solved problem in computer science?