After playing with the small RC servo motors I wanted more power, continuous 360° rotation and still "know" where the shaft is for positioning. Enter the Stepper Motor ...

 The Usual Learning Curve 
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So after mastering stepper motors and having a decent motor control box, I was ready to get back to arm building. And the "big picture" so far is this:


So on to my next arm, the 80/20 Arm ...