3D printable parallel SCARA robot arm assembly, ideally evolving into a long-reach printing add-on for our mobile robots.
Built on the AuroraSCAD library from https://github.com/AuroraRoboticsLab/AuroraSCAD
From gearbox_arm.scad for each of the two steppers you need to print one frame and one reduction gear.
From torque_arm.scad you need two armReinforced (the large geared arm), two elbow joint, and one set of tool pivots.
Driven by two NEMA17 stepper motors, and 14 tooth 32 pitch (0.8 module) gears.
Reduction gear axle pin is a 4mm bolt.
Shoulder axle pin is a 5/16" steel rod.
Elbow axle pins are 8mm aluminum rod.
Elbow rods are 9.3mm composite rod.
(FIXME: should collect all the parameters for these non-printed parts, and keep them in one interface.scad so they can be easily changed.)
Can be driven by Marlin firmware with arm degrees via these gcode commands.
Steps per unit is from: (200 steps/rev * 21.75 gear ratio * 16 substep * 1 degree / 360 degrees)
Startup gcode:
M92 X193.33 Y193.33 Z1511.79 E519.11
M203 X100.00 Y100.00 Z8.00 E100.0
M201 X1000 Y1000 Z100 E5000
G92 X90 Y90
Motion is now in degrees of arm movement:
G1 X90 Y90 F600000
G1 X0 Y0
G1 X180 Y180
G1 Y90
G1 X90 Y0
G1 X180 Y90