This section will discuss stepper motor drives as an option for the DIY CNC Project.
Stepper motor drives are more economical, generally, than servo drives.
DIY kits drives and OTS (off the shelf) drives will be discussed.
My small CNC Project uses 2nd hand stepper motors. The intent of the machine was to be able to mill pcb prototypes.
I will certainly miss options for this category so feel free to post stepper motor drive discoveries here.
DIY/ Purchased Kit Stepper Control #1 - Linistepper
This popular OPEN SOURCE stepper motor kit is very economical. You can outfit all 3 axis of a machine for $115 (version 2) to $90 (version 1). I use it on my small CNC pcb mill and have never had any trouble. If you provide adequate heat sink and cooling air, they will run as long as you can stand to hear them.
The controller chip is a preprogammed PIC and the design was orginated by Roman Black. HERE is his webpage on the board.
You can find the kits on ebay as sold by James Newton.
It is rated at 3A @ 36V for..."Enough to move a 15lb axis at 60IPS or a 30lb load at 30IPS.." according to Mr. Newton's ebay verbage. Micro steps, half steps, and more are available in the command stucture. Of course all this depends on your controlling software. I use mine with TurboCNC.
The soldering is easy, the documentation is good, and mine work great. There is no other economical choice for a small to mid level stepper drive IMHO.
I'd recommend looking into the reprap project's electronics.
The generation 7 hardware looks pretty good, works via USB (this will preclude the use of Linux CNC as control software), and is optimised for DIY. At the very least it looks like an inexpensive option that can be tested pretty quick.
Thank you Kevin.
I had heard about this project and there has been considerable effort in developing it.
A significant difference is amount of power the motors require for cutting metal (an implied design spec for this project). With RepRap, torque is only required to move the printhead to position. An case could be made for a motor amplifier that uses the RepRap base drive to drive a more robust motor. This, of course, would be another parts we would have to research/specify.
Keep looking around. Steppers are nearly everywhere and prolific.
Howdy... seems like there has been a lot more discussion regarding servos. Has that decision been made yet? I think going the closed loop commutation route with a stepper is the optimal path.