> Here if you zoom it a bit, you can see a very slight wobble in the pen tracks because it catches a bit of the paper's grain, and depositing ink, the paper "drinks" the ink which fattens the lines a tiny bit.
I think you're misattributing things. Plotters use stepper motors and so have a minimum distance they can move along each axis. Due to this, they don't produce perfect lines at an angle and do introduce similar artifacts to what you'd see on a screen.
IME older plotters use DC motors and optical encoders rather than steppers, and do seem to produce perfect lines at angles. They can't do curves perfectly, as even when you specify an arc or bezier curve, the plotter breaks it down into small straight segments.
You must be right, there also must be mechanical steps or wobble at play here. I was hesitant because my 3D printer (lower-end than an Axidraw) seems capable of smoother angled/curved lines than what we can see here. On the other hand plotters I've seen (a long time ago) seemed to not eliminate all vibration in the pen.. but I did not see a mid to high end recent plotter running.
FDM 3D printers squish molten plastic onto the previous layer, and that probably helps balance out the limited "resolution" of stepper motors. Also I'm guessing the inertia makes the extruder movement a bit more continuous, after all it's enough to cause artifacts like ghosting when printing at higher speeds.
I think you're misattributing things. Plotters use stepper motors and so have a minimum distance they can move along each axis. Due to this, they don't produce perfect lines at an angle and do introduce similar artifacts to what you'd see on a screen.