https://instagram.com/p/7RRwAnIfK1

This is a first attempt to mount the electronics. Only the base is actually on the table, for much greater range of motion at the anchor. There are already plans to deal with the USB and power cables that remain.

The firmware now has a calibration system. When I put a magnet into a sensor I have no idea which way the magnet is pointing. So when I build the machine I have to move it to a known location, read the sensor values, and then write into the Arduino's EEPROM "actually, the angle you should report to the world is now THIS." Like the Marlin 3D printer code, there is a command to change the calibration and another to save it, so one can experiment with settings before committing. This way the calibrations all take place at the firmware level. The PC software will work the same for every arm right out of the box.

With the angle values corrected it is now possible to add software limits. If you ask the robot to move to an angle outside it's defined range of motion it will stop at the edge. Less chance of robot damage is good.