newbie needs help

Hi Everyone, I am a cnc laser operator looking to build my own cnc milling machine and/or laser engraver. After checking out several projects on the Instructables website, I think I know which direction I will take. I recently purchased an Arduino Uno R3 SMD board, Grbl Cnc Shield V3.0, and 3 Pololu DRV8825 Stepper Motor Drivers. As far as I know, I've downloaded all the appropriate firmware and drivers for both the Arduino and the Grbl. Is there a website with a complete tutorial for setting up this configuration that someone just getting in can follow and understand? Seems like all the instructions assume some sort of background knowledge. I'm not even sure where to connect the stepper motors on the shield! ( don't want to burn anything up right out of the gate. lol ) :~ Any help pointing me in the the right direction would be greatly appreciated. Thanks everyone.

Is there a website with a complete tutorial for setting up this configuration that someone just getting in can follow and understand?

No. This is not a beginners thing to do. It is like asking :- I have never flown a plane before, can you teach me how to land a Tornado on an Aircraft carrier please.

Ha! Nice analogy Grumpy Mike! Yeah, I totally see that that this project is over my head at this point. Where would be a good starting point for someone to build their skills? How did you get started?

There are several CNC forums which may be sources of useful advice. And, although it is 3D printing rather than CNC machining the RepRap forum has a lot of information - and it may be more useful for beginners than some of the CNC forums.

There are plenty of Threads on this Forum about using stepper motors with an Arduino. But this is a Forum for people learning to program Arduinos. Using GRBL is slightly different because all the programming is done for you may not have much interest in what goes on inside GRBL…

You have mentioned the DRV8825 stepper drivers but you have not mentioned what motors you are thinking of using. You MUST ensure that your stepper motors draw a current that is comfortably within the range of your stepper drivers. The DRV8825 should be ok with motors that need about 1.5 to 1.7 amps. Higher than that and you will almost certainly need what is referred to as aggressive cooling.

But to an extent this is putting the cart before the horse because the first thing you need to do is decide how much torque you require from your motors. If that results in a high-amperage motor then you will need a mmore powerful driver than the DRV8825 (and probably more expensive). If you need a high amp driver it may be more economical to buy a driver board that can control 3 or 4 motors.

If you want your motors to run at higher speeds (no stepper is really fast) you should choose ones that have low resistance coils (and low nominal voltage) and drive them from a high voltage power supply.

You must ensure that your power supply has plenty of amps - stepper motors consume their full current even when stationary.

Have fun.


Excellent suggestions Robin2. The cnc milling machine that I would like to build would be rather light duty. Cutting wood, plastic, and maybe alumiinum. The motors I was thinking of using were somewhere in the lines of a 280oz nema 23. But for now I was just planning on getting an idea on how the electronics might work. I scavanged some small stepper motors from some dvd-rw units and just wanted to see if I could get movement on 3 axis. A small prototype I guess you could call it. I will definitely take your suggestions, and find some other forums that are geared towards beginners. Thanks for the info.

Have you come across my CNC project?

Just checked out your project G.M. Excellent job making use of an existing machine tool. It already has given me so ideas for my build. Hope I can post some positive results in the next several weeks. "baby steps" as the say! lol.