this Saturday we had a small but beautiful maker day in Switzerland near Basel sponsored by http://www.boxtech.ch in Lupsingen. We were building multiple meArms and I have found a couple of issues and solutions:
- at the connection of the servo horn with the servo, the acrylic plate is slightly thicker than the horn head. If you fix the horn using a screw it creates such a strong friction that the servo can melt (has happened to me). I therefore recommend to take off 0.1-0.2 mm off the acryl next to the servos so that the arm can move freely.
- the servos draw a significant amount of current when all servos move in common. This causes some ardinos to reboot and if the servos move after the boot this can lead to an oscillating boot state. This seems to be linked to the voltage regulator of the arduino board. The original UNO worked fine, the iteaduino and funduino failed to operate in a stable mode. I am now working on a i2c based servo driver board (like the adafruit one) to avoid the voltage regulator of the arduino.