I'd build a cnc plasma table. I have 4'x8' cnc plasma cutter and it's indispensable. I'd like to add a CNC mill and CNC lathe, but if I could only have one, I'd take the plasma cutter.
You can get a semi-plug-n-play electronics package from candcnc.com. It will set you back about $1,500 on the low end. A Hypertherm Powermax 45 will cut up to .5" and will run about $1,800. You can get a gantry and rail kit from .precisionplasmallc.com for $2300. You'll have to build the table itself to mount everything to, but the steel for that can be had for $300-ish. You could put it altogether for about $6,000.
The whole process comes with a pretty steep learning curve. It seems pretty simple to me now, but I remember when I dove off into it and it was daunting at first.
Basically, it goes like this and it doesn't matter if you have a mill, a lathe or a 3 axis table, it all kind of follows this path. You will have stepper motors that control the speed and location of your cutting tool (be that the nozzle on your plasma cutter or a tool in your mill or lathe). Something has to tell those stepper motors what to do. The hardware that does that are called stepper motor drives. Something has to tell those stepper motor drives what to do. That's where control software like Mach3 comes it. You have electrical wires that run from your stepper motor drives to the serial ports, parallel ports, or USB ports on your computer. Something has to send signals down those wires and that's where control software like Mach3 comes into play. Mach3 is a program that is configured to know which wires are running to which pins from your stepper motor drives and it knows how to send signals to your stepper drives, which in turn send signals to your stepper motors. Control software like Mach3 lets you control your stepper motors so you can control where your cutting tool is, how it should move and what speed it should move at. However, before Mach3 can tell your CNC cutting machine what to do, you have to create a part file Mach3 can understand. That's where CAM software comes it. Cam software converts drawings files into part program files that software like Mach3 can use to tell your cutting machine what to do and how to do it. However, before you import a drawing into your CAM software, you have to create the drawing in the first place in some kind of CAD software.
For instance, a part file for cutting a 2 inch square might contain the following lines:
G00 Z1.0
G00 X0 Y0
G01 Z0.25 F25
M03
G01 X2 Y0 F100
G01 X2 Y2 F100
G01 X0 Y2 F100
G01 X0 Y0 F100
M05
Those lines are commands. G00 is a command that tells the machine to MOVE to some location as fast as it can. Behind the command are parameters that tell it WHERE to move as fast as it can. In the case of G00 Z1.0, that command tells Mach3 to move the "Z" stepper motor as fast as it can to 1 inch. G01 is another command. It tells the Mach3 to move a stepper motor to a given location at a given speed. So, G01 X2 Y0 F100 tells Mach3 to move the "X" steeper motor to the two inch position, the "Y" steeper motor to the zero position and to move both of them to those positions at 100 inches per minute.
Now, Mach3 needs more information than this to make your machine run. For instance, your stepper motor might have a gear attached to it with 16 teeth on it. That would be the pinion gear. That pinion gear might ride on linear a rack gear that has a certain number of teeth per inch on it. Mach3 has setting in it that have to be calibrated to your machine so it knows how many steps to send to your stepper motors so that a command sent from Mach3 to move the machine 1 inch actually translates to 1 inch on the table. There are other settings in Mach3 that have to be calibrated. For instance, the wires running from your "X" stepper motor run into the stepper motor drive which then might run through a breakout board, which then run into the serial port and are attached to pins. Mach3 has to know which port is being used, which pins are being used and so on. These are the kinds of settings you'll find in Mach3 and are all a part of what makes the whole system work.
It can get really complicated if you try to understand it all and if you try to build a machine from scratch, you are going to have to know it all or you'll never get the thing off the ground. That's why an electronics package like what you can get from CandCNC.com makes the most sense. All the motors are there, the stepper drives are there, the whole thing is built and pretty much ready to go. If you build a plasma table, what you end up doing is you build the table itself, you attach a rail/gantry kit to it, you bolt on your motors, you install Mach3 and SheetCam, you configure a few things in Mach3 and then you teach yourself how to draw.
That's for $6,000. That's going to take you a long time to get up to speed. There will be times where you will want to rip your hair out and wonder why you bought all this expensive stuff which you hardly understand.
The other option is to spend twice as much money and buy a CNC plasma table made by some company. For $12,000 to $15,000 you can buy one that will be delivered to your shop, you won't have to know a lot about it, they will include some get-you-up-and-running training and you'll be cutting parts almost immediately. Of course, you have to fork out for that. The cheap way is the hard way. That's just all there is to it. See, you've asked for good, cheap, EASY and reliable.... and you can't have all of those in one package. The world simply does not work that way. The cheaper you get, the harder it gets. The cheaper you get, the more you have to do yourself and that means the more knowledge you have to have. Gaining all that knowledge doesn't fit into the easy category. Building something cheap without all that knowledge doesn't fit into the easy category. Fork over $15,000 and everything gets real easy... but we're out of the cheap category now. Also, if you build it yourself, you are the customer support... if it breaks and you don't know how to fix it, no one else does ether.
I mean, I did it. I did it cheap and reliable, but it sure wasn't easy. It took me months of reading on places like cnczone; and then it took me weeks to research, design and build a table; and then it took me more weeks to figure out how to make it actually move. And then it probably took me a year to be any good at it.
