I managed to flash Grbl 1.1 into the Arduino Uno, Install and move all three axis, they work perfect, g code sender can run the nc files im uploading. Im just stuck with the spindle.... Here is what i ...

I suspect this has been done to death but I can't get my head around it at all. I'm using GRBL 1.1h on an Uno, with a CNC shield v3.51. I have connected six limit switches, two on each axis, to the Z+ ...