Elegoo Penplotting tutorial & pen mount

For those of us who like to mod our tools and stuff, here’s a fun project to play with, more because of the concept than of the design. There are specific machines to do this, but basically, they run the same hardware as a standard printer. Keep in mind that this requires fiddling with the firmware, so DO IT AT YOUR OWN RISK. If you’re not sure of what you’re doing and its consequences, then it’s best to quit than to brick your printer.

The adapter per se is no big deal, and i’m sure you can probably modify or create any shape of adapter you want, for any printer, this one is specifically tailored to suit the shape of a standard Elegoo Neptune printhead. Just print the two parts and glue them together. The important bit about this experiment, is to share my findings when i decided to use my Neptune 4 Max as a pen plotter. I’ll try to list as many as i remember, and of course, you’re more than welcome to experiment and share your ideas here!

You’ll need:

1. a pen adapter/holder: can be this one or any shape that suits you best. It’s a first draft, a better (possibly spring loaded) mechanism is yet to come, feel free to share remixes about it

2. rubber bands: Because the whole thing is rather sketchy (more on that later) rubber bands provide sufficient grip while allowing for a bit of forgiveness in case things go south, they’ll just stretch a bit more

3. Gel pens: traditional ball point pens with standard ink (like a Bic) just don’t roll well enough. I’m using Uniball Signo 0.7 pens, they work fine. Keep in mind that the tip suffers a lot of abuse and its lifespan will be short. 

4. some stiff, thick paper or cardboard. Regular printer paper will not cushion the pen enough, and is more likely to warp. In Argentina, we use Cartulina, which is like a 300 gram paper.

5. a nice design: if you instruct any AI (i use Gemini) to give you a blueprint of anything, or convert an image to pen drawing, it should be enough. Then, a vector program such as Inkscape can vectorize it to SVG, and that can be imported directly to OrcaSlicer

Things to set up:

1. you want to keep the movements of the machine, but none of the thermal standard behaviors. Best option, set up a new printer in OrcaSlicer (or your slicer of choice), and build a profile from scratch, both for the machine and for the material.

2. The only movement you need to cancel, is the extruder. Best way to do this, set your flowrate to 0,001 in your filament profile. Not entirely zero, otherwise it just won’t draw any lines.

3. If you keep your hotend at high temperature without filament flowing through, its gonna cook any remainings inside it and degrade the teflon coupling. So, in your filament settings, set the hotend and bed temps to zero. It will throw a warning sign, ignore it, its all good.

4. Coincidentally, set up all cooling options to zero, both for hotend fans and layer fans.

5. Fool the filament runout sensor by throwing a small piece of plastic in there.

6. This is the heavy part. The printer (or at least my Elegoo, and mostly all) has a hard safeguard against printing at room temperature so that it protects the extruder engine from trying to force plastic into a cold hotend. There’s a parameter in your Printer.cfg file (in the Extruder parameters) called “min_extrude_temp” usually set to 170°, which you’ll need to set to zero, otherwise the printer will never start working because the g-code will have a zero value (from step C) but the firmware will not start until minimum temp is reached. KEEP IN MIND THAT THIS WILL AFFECT NORMAL PRINTS TOO, so when you try to use it normally, you will have to make sure YOU set up a reasonable temperature, you will not have this safeguard anymore!!!

7. in order for the printer to be able to jump from one line to the other in your drawing, you need to increase the Z-hop value to a rather large value (make it 3 or 4 milimiters just to be sure, paper tends to warp a bit) and in standard mode (so it hops fully vertical and not in an angle).

8. Speed is quite a thing. My printer throws a warning sign of drivers overheating if i use print and travel speeds over 300mm/s. Think that since you’re only drawing lines and never filling the spaces, its all stop-and-go for the stepper motors. Perhaps its because of the massive weight of a Neptune Max’s bed and the stress it poses over the Y axis, and maybe it’s ok to speed up in smaller printers. In my case: print at 100/s and travel 300/s

9. in terms of the model details, make sure you use something like vase mode. Only 1 perimeter line, no infill, no top/bottom layers. And make sure the model itself is only 1 layer of height. Your preview should look like only the outlines of the original picture.

10. Hardware-wise: set your pen height about 2 millimeters below the tip of your nozzle, and compensate it via the printer’s z-offset value, by hand, old school paper testing does the trick. It should have a firm pressure but not so much that you ruin your pen in the first few inches.  Also, this adapter will offset the printing to around 70mm forward from the standard nozzle position, so you have to account for that, both in your design size, and when positioning the paper on the bed

11. Additional steps: this is done in your printer settings in OrcaSlicer, you need to modify your start G-code to prevent it from validating preheating status and purge. This is based on my Elegoo printer, the need for this step can change from brand to brand, i suggest you run it through an AI and confirm. In my case, it just wouldn’t start with those, Klipper throws an error sign.

    1. Remove heating commands (M104, M109, M140, M190). 

    2. Delete the plastic prime line routine so the printer goes straight from G28 (home) to executing your design coordinates.

That’s about it. Additional tips include choosing a simple design to test out (i ran a bunch of concentric circles), and as always, having a perfectly leveled bed, but the rubber bands can help with this. Except for the firmware modification and the z-offset value, everything else is set up in a way in which its fully reversible so you can return and continue to use it normally afterwards. 

Sorry for the lengthy post, and the weird english, enjoy and keep on modding!!!

Remix culture is strongly encouraged, and altough appreciation is nice, main goal here is to incentivize creativity, so do your own experiments and share!