This site has been so much help for me so I figured I ought to post the progress on my first machine.
This may not be the correct forum since I am converting an old machine rather than building from the ground up.
I started with what I think was a circuit board soldering machine, but I'm not sure. It has a neat sliding vacuum table as an x axis, a y axis and another x axis above with an electromagnetic plunger as the z.
I disassembled the extra x and built a simple z, reusing the rails and guides and some 1/4-20 rod and a barrel nut for the drive mechanism. Then I mounted a small pneumatic die grinder for the tool motor.
Now the fun begins. I'm ok with the mechanical stuff but I have a lot to learn about electronics.
The motor drivers were ancient and microprocessor controlled so I got a xylotex 3 axis driver and power supply. I wanted to use an old computer which isn't fast enough for Mach2, so I downloaded a trial of Kcam. I carefully followed the xylotex checklist but couldn't get the steppers to run very well. The next day I bought a cheapo desktop and tried Mach2 and the motors ran great.
Kudos to Mach2 for their excellent manual. I would buy the program just for that. I took the PDF to Kinkos and had a spiral bound hardcopy printed so I could look at the manual and the program at the same time.
My machine has slotted photosensors as limit switches. It took me a while to figure them out (some were bad), but after playing around with a voltmeter and a pile of resistors I was able to make them output the right signals.
I put the electronics in an enclosure and added a relay to run a pneumatic valve for the tool motor.
So it's almost all put together. The relay works, the limit and home switches work, the x axis works, the y axis works, but the z does not. I have asked for help on that in the xylotex forum. I may have fried something. But that's not enough to wipe the big smile off my face. I have motion! I just stuck a pencil in the z and had the machine write my name! That's so cool.
Thanks to all you out there who helped me out without even knowing it.
I plan to use this machine for light duty engraving. My next project is to convert an old pick and place machine to a router. I'll keep posting.