Inspired by the MPSCARA, I challenged myself to build my own functional SCARA arm, but with even fewer printed parts. For example, all linear bearings are printed (built directly into the structure for the carriage). The only parts you're really gonna need to go out and buy are the linear rails, leadscrew, steppers + belts, and some M3 fasteners! Everything is controlled by a cheap, off-the-shelf 3D printer mainboard (in my case the MKS Gen L v1 or v2).
More important, perhaps, than the hardware is the software which drives the robot. I've been developing a browser-based software suite which can drive the SCARA arm, generating inverse-kinematic control code on the fly! I learned quickly upon building my arm that there is no robust firmware support on Marlin for SCARA arms (despite some confusing documentation suggesting otherwise). Thus I built my own!
Here I demonstrate the writing capabilities of the jSCARA arm + software, and the precision with which the arm can write. Note that when the drawing gcode is run for a second time, the arm traces over the exact same path!
You can see the custom designed software here: https://github.com/jpoles1/jscara-console.
This software is essentially a chrome-based gcode sender which works with regular marlin (configured for a cartesian bot wherein X-Y coords sent to the SCARA are actually angles for the arms) and generates SCARA commands.
Hope that's helpful! It's definitely not a finished product, but it's what I've got so far. Overall have had a lot of issues using marlin for this project, defintiely not a perfect fit for SCARA arms.
Marlin actually does have mostly-complete SCARA support, just no documentation on how to use it. I wrote some about it here https://reprap.org/forum/read.php?185,879148
The legendary dekutree64, thanks so much for commenting! I actually came across this thread and read through it several times trying while trying to get things to work, however I did not have much success. It would be great to get your expertise in troubleshooting if you're open to lending a hand! Will send you a DM.
Do you share your software ? I don't see it here.