Dec 01 2022

An Introduction to Pen Plotting

Tara Donavan - Haze

No artwork has affected me quite as much as Tara Donovan’s installation ‘Haze.’ I remember the first time I saw a photograph of it. I was drawn to the scale, the simplicity, and the subtle visual noise. My drawing style often leans in this direction. Lots of lines closely spaced to create textures and forms.

It’s not difficult to draw a direct line of inspiration from Donavan’s Haze to my current explorations in generative design and pen plotting. I first started using a pen plotter to print generative SVG a little more than 3 years ago. As much of my professional life is attempting to make things go faster, I enjoy the physical constraints that pen plotting places on my artistic process. While you can generate thousands of svg files to plot in the span of a few seconds, there is a slow methodical nature to printing with a pen and ink.

A couple of my favorite plots (apologies for not knowing the artist)

For me each plot is an experiment in controlling the flow of ink across paper. The constant squeaking of the servo can become hypnotic as you watch the construction of a piece unfold. As I’ve spent a lot of time in my office over the last few years, the background noise has become a welcome guest that adds a dynamic energy the space.

I’m often asked about my setup and process so this is a bunch of notes on motivations, things I use, svg resources, and helpful tips I’ve found along the way.

Intro

If you’re thinking about getting a pen plotter, my advice is to absolutely get one immediately! They are an endless amount of fun. So far I’ve found it to be a supportive community of artists.

The downsides: They do take up space + ink and paper are not free. Also, due to the extreme nature of fun, it can be quite time consuming.

Getting started is easy. As pen plotters can plot SVG, you can get going without needing to create your own unique work. Just the process of plotting is a craft by itself. There are lots of free SVG generators or static SVG files on sites like Wikicommons that you can compose, arrange, and alter in a variety of vector programs like Inkscape or Adobe Illustrator.

11" x 17" plots of clusters of thousands of cubes at various sizes

Materials

There are a lot of variables that go into the final version of a plot. The same svg file can have many different appearances depending on combinations of ink, paper, and pen speed. While not exhaustive, these are some specific brands and products I currently use. Links are not affiliate links, just provided for ease. Shop locally when ever possible.

Pen plotter

I use an AxiDraw SE/A3. At the time I started it was the largest AxiDraw available on the site. According to Evil Mad Scientest, the SE (special edition) version is higher quality than the regular A3. I have not A/B tested this myself but I trust the manufacturers. It’s been very durable over the last 3+ years, only requiring servos being replaced periodically.

AxiDraws are easy to use right out of the box. You might be surprised how quickly you can get going.

There are some larger sizes available on request now. Check out the full Axidraw lineup here.

Mat

I first tried the magnet board but I found it bent too much and added unwanted imperfections. One of the first things you notice when setting up your first plot is that aligning paper to the AxiDraw without proper materials can be more of a challenge than you’d anticipate.

I recommend getting a mat that has a grid on the surface. I have on that is 24x36. This will allow you to consistently line up both the axidraw and the printer to a fixed reference.

Mat with grid

I use masking tape to put down a few sheets of 11x17 paper. Personally I think it improves the line quality to have the pen press against a stack of paper rather than a single sheet on a hard surface. This is also how I prefer to write by hand.

Pens and Ink

For more complex plots involving hundreds or thousands of lines, different pens and ink combos can have drastic effects on the final output. There is a lot of variance in ink. Viscosity and time to dry are both things to consider. If an ink is slow to dry it can pool and bleed through some types of paper easily.

If I could only bring one pen to my deserted island it would certainly be the Pigma Micron 005. I find the size allows for fine detail work and the ink is released smoothly and consistently. They can be expensive (especially if you forget to put the cap back on) but I find them to be worth it.

Pigma Micron 005 Fine Line Pen

You can reduce plastic waste and save money by buying ink and refilling them. While I don’t have complaints about the default ink, you can really open up your aesthetic options by using custom inks.

Fountain pens

Fountain pens offer a variety of advantages, particularly in the amount and quality of inks you can experiment with. They also come with challenges. It’s difficult to get even ink flow over an entire plot. While this variation sometimes leads to beautiful compositions of texture, it can also ruin a plot.

For fountain pens I primarily use Lamy Safari pens with EF nibs. I like having several of the same pen as it makes it easier to swap out the pen on a mutli color plot and line it up correctly. They are lightweight enough to work well with the AxiDraw. I’ve experimented with several other more expensive pens and haven’t noticed an upgrade in plot quality.

11x17" - 4 color plot with overlapping lines

I also invested in a few dozen refill converters, the tubes that hold ink for the Lamy Safari pen. This allows me to keep dedicated tubes for different hues like red, blue, black, etc. which in theory helps reduce any cross contamination that would alter the colors.

While using fountain pens can reduce plastic waste, they do need to be actively maintained and cleaned.

Fountain pens are more difficult in my experience getting ink to consistently out than single use pens. You can get a lot of interesting color transitions by swapping ink cartridges with the same pen. The ink will generally shift gradually creating subtle gradients.

Inks

I haven’t found inks I don’t like at all but I’ve only used a few different brands. Pilot, Mount Blanc, Diamine, and Sailor have all worked well for me. I find ink is very contextual though. I won’t use a viscous ink from Diamine for a dense cube cluster plot.

There are some great sites and blog posts that extensively document different inks.

Paper

For high quality plots this might be my favorite paper Bee Paper Bleedproof Makrer Pack, 11x17

Paper has a lot of variance in smoothness and absorption rate which will affect how much the ink bleeds. I highly recommend experimenting with as many paper types as you can get your hands on to develop your own preference.

For making your own cards I love Darice cards and envelopes: Darice A2 & A7

Tape

I first attempted to use magnets and the magnet board to hold paper down. I didn’t always find that this held the paper properly in place. I’ve settled on primarily using masking tape to secure the paper in place. Art tape and Scotch blue painter’s masking tape work well. They won’t leave behind glue reside or tear the surface off of your paper if removed properly.

Servos

Tip: Make sure you unplug the AxiDraw when it’s not in use. This will help extend the life of the servo significantly.

Replacement Servos

The little motor that moves the pen up and down does not have an infinite lifespan. Especially if you do a lot of complex plots involving thousands of dots and lines. I recommend just buying 10-20 right away. They often die an inconvenient times and ordering can take several weeks depending on availability. There is a newer heavier duty replacement servo that I have not used but is apparently stronger, quieter, and lasts longer so seems like it might be worth the investment. I’ve probably run through about 10 in 3 years. I use my axidraw extensively, especially around the holiday season.

SVG

SVG stands for Scalable Vector Graphics. SVG is an essential material in the pen plotting process. There are lots of ways to create and generate SVG.

Blender is a free 3d software tool that you can use to create 2D or 3D SVG images.

In Edit > Preferences > Add-Ons you’ll find an add-on called Freestyle SVG exporter. Enable that and it will automatically save an SVG version to wherever your output is set to.

You can import any obj file and attempt to render it as line art. Some pieces that don’t have well constructed meshses won’t look that great. I recommend exploring geometry nodes and simple shapes to create some fun compositions.

Tips & Tricks

Pen Height

The AxiDraw controls in Inkscape allow you to toggle the pen height up and down to make sure you have enough clearance and contact pressure. Some paper is hard to get perfectly flush. It will raise off the surface slightly in the middle as the pen picks up off of the page. You generally want to keep clearance low as that will speed up plot times and extend the life of your servo.

I tape the corner with masking tape. This allows me to make sure there will be contact with the paper without having ink bleed on the paper.

Tape on the corner of paper to make sure alignment is correct without getting ink on the paper

I normally plot at about 4 / 24. If you need more pressure because you’re using a fountain pen or a pencil, you might consider setting it 1 or 2 ticks lower after getting everything set up.

Optimizing SVG files

You can optimize SVG files for plotting to reduce the amount of distance that the pen has to move. By default it will print in order of layers but this generally isn’t correlated to physical proximity. Optimizing your SVG files can have a drastic reduction in the overall time it takes to print.

The new plot optimizer for the latest AxiDraw utilities for use with Inkscape seem to be much better and faster than the previous versions. I have not dont a before and after comparison.

Traditonally I have used a CLI tool called VPYPE to configure and optimize SVG files to prep for printing that resulted in much faster print times. VPype also comes with a bunch of utilities to generate designs in SVG format. It’s one of my favorite pieces of software.

I have this function saved in my .bashrc file that allows me to quickly optimize plots.

optimizePlot() {
  vpype read "$1.svg" splitall linemerge --tolerance 0.5mm write "$1-o.svg"
}

With this saved in your .profile or .bashrc you can run optimizePlot test-plot to optimize a file called test-plot.svg. This will save a new file called test-plot-o.svg

Optimization has saved me hours on certain plots, so it’s definitely worth it.

Outro

If you are thinking about getting a pen plotter, I hope you do! And I hope you have lots of fun making art. For myself its been an avenue to connect with lots of people about art and code. There is so much left to explore in the medium. While I have only used my plotter for drawing with pen and ink, you can use it to paint with a brush, draw in sand, or create an etching on a piece of glass.