I have currently finished 3d printing the 3rd set of parts for 3 AR3 robot arms. I successfully uploaded the teensy and mega sketches to all of the control boards. feeling accomplished so far. waiting on mcmaster and steppersonline to deliver the parts for 2 of the robots. My next order of business is to figure out the safety switch setup to safely interact an arm with an arduino uno setup for an xcarve router. Currently using a LewanSoul LeArm to teach me about cnc and robot interaction. Then I will interact the AR3 with the system. any ideas on safety switches to make sure the arm is clear of the xcarve to avoid crashes? All digital I/O is used on the xcarve uno. attached is a digital side pin out of the xcarve uno.