I recently bought an mSCARA diy plotter from Makeblock, which is essentially a drawing robot kit that lets you build four different types of drawing robots.
The mscara uses two NEMA17 steppers, that have 1.8degree step length.
I uploaded a video of it drawing:
It prints .svg and after a few adaptions like shortening the arms, it runs very good.
I bought the mscara, because i got fascinated with SCARA-arms lately, especially for camera sliders and microphone stands.
As a testbed for scripts, i decided to build a small arduino/raspi based dual arm scara drawing bot.
For now, i got two low profile rc servos, hooked them up to an feather (cortex M0) board, and wrote a small script that reads out A0 and A1 as x/y-axis.
For the Y-axis (left/right) i used a similar procedure like with v-tails on an airplane.
The servos have around 160degrees of freedom stepped in 1 degree steps, so the resolution of whatever the pen might draw in the future is not too good to begin with.
The main goal of this project is to build kind of mobile polaroid-plotter, based on a raspi with a cam built into the plotter.
Or to write down emails, or tasks that you get in your calender etc.
Next step arduino-wise will be a matrix with/for inverse kinematics data for the two arms, and the penholder gets a clever lift-mechanism.
I rendered a concept of it a few days before the ball-links finally arrived: