Convert text to HPGL
HPGL is the language pen plotters and a great many vinyl and laser cutters speak. Like DXF it is a contour format — it describes closed polylines to trace — so the export writes the outline of each letter as a path for the pen or blade to follow.
Convert text to HPGLPlotter units and scale
Coordinates are emitted in HPGL’s fixed plotter unit of 1/40 mm. Classic HPGL has no unit header — the numbers are the units — so the unit selector cannot declare a scale and instead applies one to the geometry. At the millimetre default, a font size of 100 plots a cap 100 mm tall, the same convention as the STL export.
No curves in HPGL
The language has no Bézier primitive, so curves are flattened to line segments before writing. The accuracy setting controls how finely: raise it for large output where a polygonal “O” would be visible, lower it if your controller chokes on very long coordinate lists.
Draw the letterform or its outline
Fill traces the letterform itself. Outline traces both edges of a band of the stroke width around it — the natural choice for a pen, where you want a stroked-looking letter rather than a silhouette the plotter would have to fill by hand.
Questions
- Which machines take .plt files?
- HP pen plotters and their clones, Roland and Graphtec cutters, most Chinese laser controllers, and any software with an HPGL import — Inkscape and LaserGRBL among them.
- Why is my plot the wrong size?
- Almost always a unit mismatch, since HPGL cannot declare its own. Check that the unit selected here matches what your plotter software assumes, and remember the font size is a geometry-unit height, not points.