Hi I am building third cnc machine (almost done). I use 12.5Nm closed loop servo stepers with encoders, water cooled spindle very strong mechanic etc... I use Atmega 2560 on board I designed and GRBL. I have PWM to 0-10V analog for spindle but I left enable and direction signals, no FWD REW. (I used optocouplers for all signals and other psu). I made small PCB DirEna to FwdRew. It works perfect, so if anyone need something like this be free to ask me for DipTrace files of pcb and schematic.
