Arduino Uno GRBL slave axis end stops

[ArminLinder]

Hi all,

I currently have a 3 axis milling machine set up and working. For mechanical reasons I'd like to change one axis from a single spindle layout to two parrallel spindles. Running two stepper controllers by wiring them in parallel has already proven working well. I have a problem with the end stop though, since the Arduino Uno Board I am using supports only three inputs for end stops. I need a fourth for the additional spindle. For leveling the 2 spindle axis after a motor stall I need to home the gantry against one switch, then turn off one spindle and home the other spindle.

Does anyone have a really smart idea how I can achieve this with my uno board, or ist there any way to achieve it with one of the larger Arduinos which do have more IO ports, the Mega2560 for instance?

Thnx, Armin.

[hfjbuis]

You could connect the ends of the 2 spindles using a timing belt so that they are always positioned the same. To align the two spindles, you could turn one of the shafts after loosening the shaft coupler screw. My artillery genius 3D printer is setup this way.