LY Drawbot setup: From a box of parts to drawing SVGs

25 Feb 2025

I recently acquired and assembled a pen plotter!

Animated gif of pen robot drawing squares.

It’s an LY Drawbot, size A4, controlled by an Arduino. More generically, it is a type of computer numerical control (CNC) machine that uses a Cartesian coordinate system:

Photo of LY Drawbot pen plotter.

G-Code commands are used to move the plotter pen to specified coordinates at specified speeds, as well as control the pen’s height, which determines whether the pen makes a mark as it is moved around.1

In this post I describe how I got my LY Drawbot assembled and running, as well as provide some observations and next steps for exploration. Thanks to some excellent pre-existing documentation the build itself isn’t particularly long or involved.

What type of plotter, and why?

Many of the plotters on the market are kind of pricey and take up a Certain Amount of Space, so fit neither my workspace nor my budget.2 The cheapest one I could find was this LY Drawbot, from AliExpress, which was in-budget but felt risky in terms of quality or assembly effort.

Luckily, I then found Pierre Paslier’s 2020 write-up “LY Drawbot, a $70 pen plotter”. Pierre vouched for this model being “a good fit if you’re a maker on a budget and you’re not afraid of troubleshooting.” Excellent! That is, in fact, me.

I put in my order—$122 including shipping—and eight days later it arrived in the mail.3

Photo of pile of cardboard boxes and metal hardware blocks, ready for assembly.

Hardware assembly

This part was super fun, and relatively easy. I’m not going to detail the assembly much—if you’re assembling your own, do as I did and follow Pierre’s write-up!

Photo of rows of baggies of different screw sizes.

The seller provided supporting documentation, which turned out to be identical to the instructions that Pierre linked. The assembly documentation is comprehensive and well-illustrated: with the exception of one page, the text was basically extraneous. It felt like nothing so much as assembling a Lego kit.

Photo of assembly page.
Photo of in-progress assembly, where built component matches on-screen component.

I used Google’s image translate to decipher the lone line of text that wasn’t clear from context:

Photo of translation between Chinese characters and “tighten the screw”.

Easy! Done.

Photo of Arduino attached to end of gantry arm.

The fully assembled plotter forms an XY gantry, with an Arduino at the end of the fixed axis and a pen holder at the end of the moving axis.

Photo of LY Drawbot pen plotter.

It feels solid and heavy; some of the pieces are metal, some plastic, but none of it feels cheap or otherwise hacky. The notched belt responsible for the gantry’s movement is fastened with tiny zip ties, which I was originally skeptical about but have worked out great so far.

A few of the 3D-printed components didn’t exactly match those in the book, but it was fairly easy to figure out which way to orient them; I only had to disassemble and re-assemble one section after making an incorrect guess. Here’s a photo of that section in situ, in case you run into a similar issue with your own build:

Photo closeup of base assembly.

Overall the assembly went very smoothly, and was quite relaxing. I accomplished it over two evenings, moving at a slow-and-steady pace. I could have completed it faster if I’d wanted to, and someone experienced with assembling these types of materials could probably get it done in an hour or two.

Post-hoc hardware adjustments:

Photo closeup of pen holder.

Software setup

Once assembled, I plugged the power cord into the wall and the serial USB cable into my laptop, and…now what? The Arduino lights were on, the fan was spinning (inaudibly!), but I had no idea what to do next.

I checked the seller’s documentation—a big zip of documents and software that were mostly in Chinese, and which referenced images of desktop software that I didn’t really want or want to install. So I skipped that, and worked from Pierre’s notes once more.

Specifically, I:

  1. Installed the CH340 drivers on my laptop (OSX), following the Sparkfun instructions here. My laptop immediately and automatically restarted upon their installation, which was distressing.

    Now that I’m rereading those instructions, it seems the drivers were actually pre-installed on my current machine, so my [re-]install was extraneous! Whoops.

  2. Verified driver functionality by powering the plotter on and plugging it into my laptop, and then running ls /dev/cu* in the terminal. I saw /dev/cu.usbserial-110 in the output, which confirmed that my laptop recognized the that the plotter was connected.

  3. Installed Universal Gcode Sender (UGS)

It’s alive!

It was trivially easy to connect to the plotter via the UGS interface:

Screenshot of UGS “connect” panel

After connecting, the first thing I did was use the Jog Controller’s X and Y commands to to move the plotter arm around in individual steps. Notably, moving the pen holder up and down requires typing M5 and M3 S1000 (respectively) into the UGS console; the Jog Controller’s Z button has no effect on the plotter.4

Fixing a pen in the pen holder was easy enough; it took some fiddling to adjust to an optimal height for any given pen, but wasn’t hard, just a little annoying. I was expecting the type of pen to matter a lot more than it did, but most pens I had lying around worked. Ditto the type of paper—I taped a small stack of printer paper to the table with masking tape (to keep it from moving around) and found that to be sufficient.

Photo of scratch paper with lines drawn by plotter, including an owl.

Plotting SVGs

Plotting individual images via UGS was similarly straightforward—and extra fun, due to Olivia’s collaborative assistance. We used an online tool to convert an SVG to G-Code, then uploaded and plotted the G-code from UGS:

Multicolor plotting

Before moving on to my list of “level up” tasks, I wanted to draw one intentional multicolor piece. I really like Georg Nees’ “Schotter”, so used Antoine Beyelers’ parametric “Schotter” implementation to generate a set of six slightly-varying SVG images, using a different random seed for each image.

Screenshot of program that outputs Schotter series.

I rotated5 and converted each SVG to G-code, and then plotted each one sequentially with UGS, with the same starting coordinates each time. I stopped between each file to switch the pen’s color. To keep from having to swap out pens and adjust their relative heights each time, I used a pen that contains multiple color cartridges.

The result would have been cleaner if I hadn’t accidentally hit the wrong commands in UGS a couple of times(!), resulting in drawing an errant incorrect line and needing to re-set the pen’s home coordinates manually. Ah well! I’m reasonably happy with the quality of the resultant piece given the minimal effort involved in tuning it to be cleaner:

Photo of multicolor plot of drawn squares, with pen on top.

Plotter observations

In no particular order:

Next steps

Here are some basic things I’d like to do next, in relative order of importance:

I have a whole list of slightly-less-basic projects I want to try, also, but am going to keep those closer to the vest for now.7 Stay tuned!

If you are a person who knows me irl (or via RC!) and you want to pair on any of these with me, reach out and let me know which one(s)—so far this has been an exceedingly fun project to collaborate on.

Thanks to Alex for the pen holder fix and general enthusiasm; Olivia for her SVGsploration companionship; and Pierre Paslier for the excellent write-up that sold me on this plotter in the first place.

Footnotes

  1. This may go without saying, but is a key source of hilarity/frustration while plotting—it is quite easy to draw lines that you do not want, and alternatively to move the pen around while leaving NO lines when you do want them!↩︎

  2. There are a bunch of instructions for cool DIY plotters out there, too, but my current interest is in playing with plotting rather than learning how to source/build a plotter, so those were out.↩︎

  3. When I ordered it, I was told it would take three months to arrive, which was perfect: it would be a carrot dangling at the end of some less creative work that I needed to do at the beginning of the year. And then it arrived super early! I thought about waiting until March to set it up anyway…and then didn’t. It has been a rough few months. I needed a little treat.↩︎

  4. In my limited understanding, this is because the Z-axis control is relevant for CNC tools that have a Z-dimension (routers, milling machines, 3D printers, etc) and a no-op for a 2D tool like an XY plotter.↩︎

  5. …I needed the orientation to be correct on the plotter. This absolutely seems like something I could do with a single G-code command, and I feel a little silly admitting to having rotated it using yet another program! But I don’t know G-code well enough yet, so this was an easy short-term fix.↩︎

  6. Not everyone thinks so: at least one onlooker has declared it unmanageably annoying, and noted that if the plotter were in HER house, she’d need earplugs. Ah well, Mom, we can’t all have good taste. :)↩︎

  7. In person I can’t shut up about these, so really I’m only feigning secrecy here so that I don’t have to write any more words today!↩︎

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