Building a CNC machine

Hi guys, first time poster here!

So I just purchased a CNC mahine frame on amazon (it comes with everything but the brain). I decided to go with arduino because opensource is awesome and I've used it before in my free time and had a chance to mess with them a bit in my engineering class.

Anyways, I'm doing my own interpretation of NYC CNCs tutorial (it's a great resource for anyone interested in machining, CAD etc.). In the tutorial he uses a GRBL shield to control the servos. I already have an arduino mega 2560 and an Ethernet shield so I'd like to hook this up to my router and have it mill in the garage while i browse reddit for cat pictures in another room.

I'm a newbie when it comes to arduino. I have a decent grasp of circuit logic, and programming so I'd like to use this as a learning experience. So I was planning on hooking the arduino, 3 servos and L293d chips up on a breadboard before soldering it all to a prototyping shield. Basically I'm trying to find out if this is the right approach and if I'll still be able to use G-code sender to control the steppers.

The scope of this question is so large, I think you need to address it to a dedicated DIY CNC forum.

e.g. www.cnczone.com

Post a link to the datasheet for the stepper motors you have AND a link to the datasheet for your stepper drivers.

I have no idea what role either L293 chips or servos can have ?

You may find some useful stuff in stepper motor basics

...R

it's a bipolar motor with 4 leads. http://wiki.zentoolworks.com/index.php/Nema_17
here's the datasheet on the L293D chip I'm using http://arduino.cc/documents/datasheets/L293D.pdf

so the motor wants to be driven at 2.8VDC and 1.68A.
I'm new to reading these types of charts and the one attached to the stepper driver is a bit confusing to me. Basically want to figure out how to get 2.8VDC and 1.68A. I'm planning on using a transistor and having a separate power supply for the steppers. What i want to figure out now is if the following will work:

I'll be using the same setup shown in adafruit's tutorial. since I'll be using the Mega I have enough digital pins to drive 3 steppers. But what I'm planning on doing is putting a transistor in each of the lines going to the steppers in adafruit's diagrams and having a power line with 2.8v 1.68a going through the transistor to the stepper and everything having a common ground. I just want to know if this sounds like a good approach or if there's anything I've overlooked. The steppers need to be grounded on both ends when idle to keep them from moving right?

rlew:
So the motor wants to be driven at 2.8VDC and 1.68A.
I'm new to reading these types of charts and the one attached to the stepper driver is a bit confusing to me. Basically want to figure out how to get 2.8VDC and 1.68A. I'm planning on using a transistor and having a separate power supply for the steppers. What i want to figure out now is if the following will work:

No, it does not. Look at #3 and read the thread linked to.
Get a current controlled chopper driver and a power supply with as high a voltage as your driver can tolerate.

rlew:
So I just purchased a CNC mahine frame on amazon (it comes with everything but the brain). I decided to go with arduino because opensource is awesome and I've used it before in my free time and had a chance to mess with them a bit in my engineering class.

Consider the Ramps 1.4. It's a shield for the Arduino Mega designed for 3D printers and can be purchased with stepper drivers and the Mega.

I CNC'd a 7x10 Mini Lathe with an Uno and Easy Drivers and love it, and am upgrading it to the Ramps 1.4 & a Mega.