BrachioGraph - the cheapest, simplest possible pen-plotter

BrachioGraph - arm-writer - is an easy-to-build pen-plotter, driven by a library of simple Python applications.

'The BrachioGraph plotter'

The hardware

  • two sticks or pieces of stiff card
  • a pencil or ballpoint pen
  • 3 servo motors
  • a Raspberry Pi, to drive the servos and run the custom code

Tools required:

  • glue
  • a ruler
  • a knife (if you need to cut the card)

The software

  • brachiograph.py, to draw images using the servos
  • linedraw, a fork of a library to vectorise bit-map images
  • turtle_draw.py, to help visualise the drawing area of the plotter
  • pulse_widths.ipynb, a Jupyter notebook to help understand the characteristics of a servo motor
  • pantograph.py, to draw images using an alternative plotter design

From bitmap to plot via vectorisation

'Anselmo' 'Prague'

Contents

Get started

Build the machine, install the software, make basic tests

How-to guides

Improve the calibration, process images, visualise plotter behaviour, alternative designs

Explanation

Understanding the mathematics, choosing hardware.

Reference

Guide to key classes and functions