Hello,
i have an CNC machine from china a year ago and i didnt use it because the motor not moving smooth,
i am thinking to upgrade the controller by connecting arduino to the stepper in the old control box to
controlled by Arduino, i search for long time and i found arduino program which called Grbl and i want
some one to help me and tell me if can connect the arduino with the old control box stepper, and if
there any way to connect it late with Mach3
ask on mach3 forum
any body can help me just to conncet the arduino with the YOOCNC controller
i need some one to help me where to connect the out from arduino to the YOOCNC stepper board
Well... I think we need more info on the YOOCNC controller.
GRBL on an Arduino outputs step and direction signals. If that is what the YOOCNC controller accepts from the computer parallel port, this change should be possible.
I'm probably going to do the same thing to change a HobbyCNC stepper driver board from parallel port to USB.
i have an CNC machine from china a year ago and i didnt use it because the motor not moving smooth,
Had the same problem 
Replaced the driver card with this one (microsteps = 800 steps/mm)
and went to USB control
Works pretty well now 8)
Have a look here
the yoocnc controlled work if you run the machine slow, most boards it is 50-50 if they will work properly in the first place you can connect an arduino to mach3 it has to be done through modbus.
the cheap chines cnc control boards are all a risk I have seen post where people have brought 3 or 4 of the same board because of the cost quite often they have used up all of them after a year, then they go get a good quality controller and never look back.
cheap will always be a risk.