Nicer text with an AxiDraw pen plotter

~ nelsonminar

(Expert readers; skip down to “The Good Stuff”).

I’m looking for some tools / inspiration for creating text with my pen plotter. The issue here is that most of desktop typography doesn’t apply to plotters because it all relies on filled fonts, effectively bitmaps. Pen plotters draw single lines. You can try drawing and filling the outline of a traditional TrueType font but that seldom looks good. OTOH there’s a whole art form of handwriting text with pens, so maybe some ideas from artists that can be borrowed?

Unfortunately traditional calligraphy is out because most calligraphy requires varying pen pressure to change line width and that’s something an AxiDraw and most other plotters simply can’t do. You can get somewhere using an italic nib (basically a pen tip that’s a wide line, not a point) but it’s pretty tricky. And it still relies on you having a font to draw the shapes.

The other quick solution is what’s called “Hershey Fonts” (after a Dr. Hershey!). AxiDraw has support for them as does this third party product but the actual classic Hershey fonts are, let’s just say, unaesthetic. The image below was plotted poorly with a bleeding pen on cheap paper, so ignore the dots and bleed, but nothing’s gonna fix these tragic shapes.

Update: when writing this up I neglected to talk about the EMS fonts, a series of free SVG fonts included for use with the HersheyText 3.0 plugin and SVG font format

The Good Stuff

So I asked on the drawingbots Discord for inspiration and got a couple of good suggestions.

A simple option is to just use better fonts. Single Line Fonts sells a handful of nice looking fonts for very modest prices, $20 or less. (And try the coupon TAKE25OFF). A bit heavy towards cursive scripts (but not true cursive, since the letters don’t actually connect.) There’s a very limited set of SVG fonts but a larger number of TTF fonts. I think those can be used with an AxiDraw OK, they mention that each line is drawn twice because of technical requirements.

A more sophisticated (and expensive) option is Quantum Enterprise’s single line fonts. There’s 59 fonts in a variety of styles. At $130 a font these aren’t cheap! But they’re nicely designed and have a lot of technical details on how to best use them with AxiDraw. Also these aren’t simple fonts; they have variant characters so that you can draw text without every single instance of a letter looking identical. They have a software tool (“Scriptalizer”) that will render variable text for you, demo it here. They also offer a service that will generate a custom font from a handwriting sample for $350.

Inspirations

One interesting point someone made is that a lot of what’s driving handwriting with plotters is marketing. Folks trying to mass-print mailers that look like they were hand written so you don’t just throw their junk mail immediately in the trash. I wonder if that’s part of AxiDraw’s business; you’d want a faster machine for mailing thousands of pages but it’s suitable for small runs of envelopes, etc. Anyway, sleaziness aside I’m glad to lift any approached they’ve developed. One interesting merchant in this area is Handwrytten, they sell robot-hand-written cards as a service ($3.25 a card!).

But what I really want to see is experimental / artistic plotter typography. Something like the explosion of interesting art folks were doing in the early 90s as desktop publishing technology made it so easy for artists to manipulate text. Stuff like this or this, only plotter-focussed. Someone must be doing this kind of work out there but I haven’t found it yet.

I’m also wondering what the state of the art is for true cursive script being generated in software. Something similar is essential for Arabic typesetting and is more-or-less a solved problem, so it seems likely that English cursive script could be doable?

Updates

There’s some good resources on the EMS Wiki also here. And some other stuff.

I tried taking a TTF font from vLetter (Hobbs), converting it to SVG font format with Convertio, and then using it with Axidraw Hershey Text (in Inkscape). Unsurprisingly this generates an outline font, not a stroke/engraving font, so each character is overdrawn twice (slightly off shifted). Probably no point converting the TTF to an SVG Font; the text to path tool in Inkscape can do the same thing. Anyway, my sample of 10pt text looked OK with a very tiny 0.05mm Staedtler pigment liner but it’s obviously not as good as a real stroke font. (Note the tiny hollow letters; that’s a fine nib on that pen, anything normal width would work better.) It’s not a bad option though if you want a quick handwriting look; vLetter has a lot of free handwriting fonts.

Playing with this made me wonder how hard converting a TTF outline font to a stroke font for SVG would really be. Taking the centerline of the font would be one possibility, although you would have to identify that with some heuristics (maybe following the TTF outline?) Also generating a path that’s inset a bit from the outside of the bitmap would work more nicely than centering the path on the edge; that would account for the width of the pen ink. For research, a program called SFEdit can do it but it looks like all it does is do centerlines for paths (not fonts).

BTW I’m a total novice at Inkscape, but the way it handles flowed text is confusing to me. I had reasonable luck flowing text to a circle and then converting it with Axidraw’s Hershey Font extension. First I had to do Text / Convert to Text to change the type from “text flow-in-shape”. Also it only worked if the text was left justified. Center justified ended up being positioned entirely wrong.

Mike Migurski reminds me his Skeletron project solved a similar centerline problem, for maps. Code is here. He says he designed it using ideas from this paper. Hand-waving a lot, the technique is to calculate Thiessen polygons (related to Voronoi diagrams) for the roads, then calculate the center of the edges of those polygons. The flowline for the center of the road goes through those polygon centers.

Some links on automating centerline creation in Inkscape: