These are beloved plotter printers from HP, first introduced in 1983. Bre Pettis donated his modified 7575A back in 2021 during Haystack Labs.
Modifying an Old HP7475a Plotter to Work Over USB
GitHub - golanlevin/DrawingWithMachines: Resources for the CMU Drawing with Machines Course
A repository of helpful information working with the HP7574
The main thing you will need to draw with these machines are HPGL instruction sets. There are several ways to do this.
| Command | Meaning |
|---|---|
IN; |
Initialize, start plotting a job |
IW; |
Set machine to imperial mode |
PU; |
Pen up |
PD; |
Pen down |
You can create HPGL files using a command line tool vpype . This application is built in Python and can be used as a library for building your own drawing applications. Below are two simple recipes for generating HPGL from a svg.
vpype read input.svg write --device hp7475a --page-size letter --landscape output.hpgl
vpype read input.svg linesimplify reloop linemerge linesort write --device hp7475a --page-size letter --landscape output.hpgl
For a more information about working with vpype, refer to the vpype page.
You can also use Inkscape, the open-source vector graphics program, to design and save SVG files as HPGL. This method is more user friendly than the command line tool, but may have limitations when trying to optimize for the machine.
brew install inkscape