I am going to build a CNC router, for aluminum, wood and maybe some iron.
It will be around 70cm x 70cm (not decided yet) - And 3 axis (3 stepper motors)
I have been looking at Nema 23 stepper motors:
I know i don't need 2 axels, but they are cheap, and can take 30 kg/cm.
Here are the questions:
Are they a good choice for this project, or can i go with the short Nema 17 (4kg/cm), even if i make the CNC 100cm x 100cm?
What stepper-drivers should i use for the Nema 23? (i have some Arduinos if necessary) - should support 3 amp per phase
The drivers should be cheap (I am a student :D) I have been looking at these: http://goo.gl/7T8xi9.
And i need something to connect the driver to my computer.
I don't know how much torque you need and there is a huge difference between 30kg-cm and 4kg-cm.
That stepper driver seems suitable for the big motors - the important thing is that the drver can comfortably supply the current required by the motor. It may be worth searching to see if you can find a single driver unit that can control 3 motors - should be more economical.
What do you mean by "connect the driver to my computer"?
Do you mean "to my PC"?
Do you intend to control the stepper drivers with an Arduino? (The Arduino can connect to a PC)
What Arduino software do you intend to use (GRBL, perhaps) or do you plan to write your own?
What software are you planning to run on your PC?
You may get a lot more detailed information on some of the CNC forums. This forum is mainly for people who want to write their own Arduino programs.
I intent to use some kind of g-code program - it does not matter if i use an arduino, but i will not write the code myself, because i am not an total expert in c++
What i meant was: The pc is connected to an unit, which supply the signal for the stepper motor driver. - I need to find one, or find out if arduino is ok?
Mejdal:
it does not matter if i use an arduino, but i will not write the code myself,
is it just plug-n-play, with some g-code program
I doubt if you will get an answer here. As I said earlier this is a Forum about the Arduino system and programming for it.
That link to the motor drivers mentions Mach 3 (etc) and a PC parallel interface. You need to ask in a Forum where people understand Mach 3. You should also be aware that modern PCs don't have parallel interfaces and, as far as I know, a USB - parallel adapter is NOT suitable.
Without meaning to be unkind, I think you need to do a bit more reading before you spend money so that you know enough to choose a complete set of compatible components - hardware and software.
You use a CAD program (e.g. AutoCAD, FreeCAD) to create a model to cut on your CNC. You then use a CAM program (MeshCAM, PyCAM) to convert that model into G-code -- a standard language for controlling the movements of a CNC machine. Then you use controller software (Mach3, LinuxCNC, or Arduino-based GRBL) to translate those G-code commands into signals sent to your stepper drivers / spindle control / etc.
When used with CNC the parallel port is just treated like a bunch of I/O pins. Yes, you could wire the step/dir pins on your stepper drivers directly to a parallel port cable if you were willing to accept the risk of accidental voltage spikes or miswiring blowing up your computer, but usually that wiring is done using some sort of parallel port breakout board that includes optical isolation and easy wire connections. There aren't any hard and fast rules that state what pin in the parallel cable controls what function of the CNC machine; this is always set in the controller software. Why the parallel port and not USB? Mostly legacy reasons; nobody has come up with any standards for a USB interface.
When you build your first CNC router I'd suggest starting with a mediocre design. Just use some cheap allthread for your leadscrews and tapped wood/plastic blocks for your leadscrew nuts. Stick with wood for your frame/gantry/etc. What you're going to learn from building this first, cheap machine is going to be extremely valuable when you start planning your second, expensive machine. What you don't want to do is build an expensive machine that doesn't perform well.
Mejdal:
found many solutions, but they do only support like 2,5 amps and such, which is not enough.
As long as you are conscious that the proper amps rating is only one part of the jigsaw puzzle.
Thank you for telling me that an adapter doesn't work
I didn't say that. Many people use that sort of controller connected to PC parallel ports. It's just a case of making sure all the parts and the software work together.
You said cutting metal. that instantly puts your needs into the commercial type of drivers.
I would go for the linked motors and look seriously at the Gecko drivers. you will not be unhappy, although they cost quite a but more than the hobby drivers.
I think there are some who use the A3977 chip. much lower cost and less power.
search some of the CNC forums and talk to people cutting metal. try to get feedback on what drivers they use.
