penplotter

A penplotter is a drawing device that uses one or more pens to render vector graphics on paper. Unlike raster printers, which deposit ink in a grid of dots, a pen plotter traces precise lines by moving a pen carrier along defined paths. The system typically includes at least two axes of motion and a mechanism to lift and lower the pen, allowing pen-up travel without drawing.

Operation relies on two-axis movement controlled by motors, usually stepper motors or servos. A pen is mounted on a carriage or head that traverses the paper along the X and Y axes. Some plotters use a rotating drum for paper transport, where the pen carriage moves along a perpendicular axis; flatbed variants move the pen over a stationary sheet. Pens can be swapped, and different ink types such as ballpoint, felt-tip, or marker may be used. Modern designs may employ lightweight CNC-style rigs and digital control.

History and types: Penplotters gained prominence in the 1950s and 1960s for engineering and architectural drawings. Early manufacturers included CalComp, Versatec, and others, with Hewlett-Packard popularizing HPGL as a common control language. While raster printers largely superseded plotters for general use, penplotters continued in specialized settings and artistic use. The main categories are drum (drum plotters) and flatbed plotters, with some models offering multiple pens for different colors or line weights.

Control and data: Plotters use vector-oriented languages such as HPGL/HPGL2 or vendor-specific commands, sometimes mapped from modern formats like SVG or G-code via converters. Open-source and hobbyist projects, such as AxiDraw, enable contemporary users to operate penplotters with modern software and operating systems.

Applications: Penplotters are employed in technical drafting, architectural and engineering drawings, textile design, educational demonstrations, and generative or calligraphic art. They remain a niche tool for large-format, clean-line drawings and creative experimentation.