im from germany (so sorry for my bad english) and new in this forum. Im planning to make a small CNC machine and need your help because i will have some questions now and in future.
Do you know if it is possible to program own commands for this board in the normal Arduino IDE without a G-code just for testing the stepper motors and so on?
I mean is it possible to set each pin from the 4 wire cables to the stepper motor to high or low manually like normal outputs?
And I have another question (I know its not the correct section in this forum for kind like this but):
The board uses A4988 stepper motor drivers, does somebody know which stepper motor i can use? What voltage must be used because the board is supplied by 12-36V so i need motors with the same voltage? And which kind of motors i will need? Unipolor or bipolor?
The A4988 stepper drivers are for bipolar motors. The max current the driver can handle is stated to be 2 amps but I believe that 1 amp without cooling and 1.5 amps with cooling is more realistic. So you should look for motors that don't need more than that amount of current.
The A4988 driver board will have a small preset potentiometer that you use to set the max current to suit your motor. When that is set you should drive the motor with the highest possible voltage to get the best torque at higher speeds.
The voltages mentioned in the motor specifications are irrelevant. The current capacity is the important thing - and the torque, of course. The specified voltage is usually the voltage that will supply the max permitted current taking account of the resistance of the coils when the motor is stationary.
I don't know anything about the shield you mention but I can't see any reason why you can't write your own code. Grbl is just a different sketch (slightly more complicated :)).
ArduFuzzi:
Do you know if it is possible to program own commands for this board in the normal Arduino IDE without a G-code just for testing the stepper motors and so on?
It would be simpler to learn G-code and worthwhile in the long run -- it is not as hard as it seems. "GcodeSender" can be used to send "test" commands.
Robin2:
The voltages mentioned in the motor specifications are irrelevant.
Comparing two motors of similar size and amperage, the motor with the lower voltage rating will have a lower inductance. A lower inductance means it will be more responsive / faster than a higher inductance motor. I do understand the point you were trying to make but I'd suggest stopping short of saying that the voltage rating is "irrelevant".
To the OP, you're looking for a voltage rating around 3V.
Chagrin:
You already mentioned that. I didn't want to sound condescending by repeating it.
Don't worry. I wouldn't have thought it condescending. I was just worried that the OP might think your advice overrides mine.
By the way I have these 12v motors https://www.sparkfun.com/products/9238 (and Pololu A4988 stepper driver board) which I bought because they were reasonably priced and seem to have enough torque for what I want. However I haven't completed my project yet.
I think what you are asking is 'can I send raw pulses to the individual stepper coils with GRBL?'
I am certainly no expert with GRBL, but I am pretty sure there won't be fine-grain motor control via the 'serial-interface' that GRBL presents. The whole idea is that all the code for low-level pulsing is done by GRBL. An analogy would be an electronics box/enclosure which you control with buttons/keypad/knobs on the outside 'interface'. The GRBL.hex file is the inside electronics, which, no, there is no prevision for directly controlling individual motor pulses. The 'knobs/buttons' on the 'interface' understand gcode. Perhaps the developer may have some method he uses for debugging, perhaps.
If you just want to be able to drive each axis independently step-by-step then it is a rather trivial matter. You just send a gcode formatted command. GRBL translates it and does the actual pulse driving.
