stepper control boards and their functions

[cyclotron]

Hi all,

I'm going to build my own cnc router but, while I feel confident i can build the framing and such, the electrical engineering side of things mistifies me. I'm planning on just buying a stepper control board but I'm not sure what the relationship is between the board and the CAM software. I use macintosh, and as such, I have found a board that uses a seriel interface rather than parallel ports. I also have found a CAM program. What I don't understand is whether or not the board itself has its own software. That is to say: Does the CAM program comunicate directly with the board or do I output CAM files (gcode?) to another program that controls the board directly? The board that I'm looking at claims it comes with software, although its unclear to me what that software is for. The software it comes with is for windows, but I found a site where a fellow in the uk used the board with a mac (hense my interest in it...) here are links to the stepper control board supplier and to the site if the guy using thiem with macs.

http://www.simplestep.com/products/products.html

http://www.sea-gull.demon.co.uk/
click on the section "cnc"
Any info on the subject, or interpretations of what is said ont he web pages would be greatly appreciated. Thanks!

[Torchhead]

Methinks you are in for an odessy of challenge. The general approach to using a PC for a controller is to use a cheap piece of hardware for a DEDICATED control function. It's only function in life is to take industry standard g-code and spin motors to make parts.

The use of a MAC as a controller does not seem to be a logical choice regardless of how comfortable you are with the machine.

The Simplestep product is a basic set of motion controllers. You will be dumped down into the depths of serial communications and using a proprietary piece of software to talk to their controllers. If you are lucky enough to get the Windows software to run on your MAC then all you will have to do is find/write an interface that will take simple g-code (which most CAM programs spit out) and translate that to their internal motion commands.

If you do find a software solution that takes g-code in and drives their cards (which in the quck scan I did don't seem to be motor "DRIVERS" but are the communications interface. They specifically exclude Gecko Drives (your best source of low cost power drives) The Sea-Gull solution is basically a CAM program that acts as the motion control too. You better like the way it works and the user interface because you won't be able to use anything else. It only imports HPGL plotter files (I'll leave you to discover the shortcomings of that approach!)

What you will be missing:

MACH3 Controller software. Over 7000 users and 5 years of development. Windows only. $159.00 for the software and it doesn't need "controller cards" running on RS- anything. Just a parallel port and a low cost breakout card and some good motor drives.

Xylotex 4 axis drive card. Directly drives steppers up to 2.5A. Takes Step & Dir in from a parallel port.

Gecko Drives for larger stepper motors or servos.

SheetCAM for 2D and 2.5D routing, milling and plasma cutting. 166.00 gets you a real GUI interface and things like tabs, parts duplication, different Posts for various controllers, etc

Vcarve for doing so amazing decorative and sign carving.

I could go on and on. I know that you are not in the US and that Windows based computers may not be as cheap as they are here but you will be jumping out of the mainstream of Small Shop CNC world in the US where most of the major help and activity is.

If your intent is to have a learning project then the MAC and SimpleStep will do a fine job of that but if you actually want to make parts rather than spending you time twisting in the wind by yourself then you need to look into what the bulk of this group uses.

Just my take on the subject.

Tom Caudle
www.CandCNC.com

[cyclotron]

Hey Torchhead,
Thanks for the info!
I have definitely re examined my priorities, and making the jump to mac is not really at the top. I know my profile says otherwise (and I have since changed it) but I live in philadelphia, and in this bountiful land of ours, i'm sure i can find a working pc thats being thrown out in the trash. So, the mac thing can be easily avoided. (The newer macs can run windows! but i'm not rich enough to have one...) I'm absolutely interseted in cutting parts in plastic and eventually aluminum. With that said, I think I should just do what needs to be done to get me to that goal.
You have mentioned a few products in your post like the MACH3 software and the xylotex drive cards. Are other programs besides MACH3 able to communicate with other cards besides xylotex? Can MACH3 communicate with other cards besides xylotex? How much can I mix and match when it comes to the boards and the software? For the time being, the main constraints on this project are cost related so I am interested in software and hardware that is cheap but won't be limiting in the future (like having proprietary software that isn't compatible with upgrades to the system or parts. )

[Torchhead]

MACH3 puts out basic step and direction pulses through the PC parallel port, to any motor controller(s) that uses that signaling. Many do. It is a Windows based Software Controller. The bad news is that you can't run it on a dumpster PC. Takes a 1G or better processor and 256M Ram.

If you are looking to do it cheaper then look at EMC (free) running on Linux. Takes less horsepower. You must be willing to be a little more techie and deal with Linux issues.

If you don't mind DOS there is TurboCNC as well. Xylotex is a cost effective stepper drive card that works with any of the mentioned Controller options. So do the Gecko stepper and the Gecko Servo series since both are Step & Dir signaling.

If your interest is making parts and not learning technology then it's hard to beat the Xylotex and MACH3 combo for smaller machines or the Gecko and MACH3 combo for bigger stuff.

TOM CAUDLE
www.CandCNC.com