Im using Makita M3700B Trimmer as spindler but I expect to fix Grbl command to stop movement for the X, Y or Z axis roller, otherwise damage the belt and stepper motor.
You talked about D11 & D12 pin that for Ramp or another board, but Im using CNC shields V3.0 board and it showed me x- x+ y- y+ z- z+ pins.
GRBL Command has error of alarm after hit to the limit switches that I showed the picture on this comment, and the roller refused to move when I click Y axis button on UGS software.
You see the green oval drawing mark on CNC shield picture show you where is X Y Z pins
