Ok, I decided to build a very quick and dirty practice table to get some CNC experience before I buy the stuff to build the final gantry. I picked up 6 brand new Thompson 1" double linear bearings and 2 44" rails a couple of years back for about $50 scrap (by weight!). I also got a second set of 3/4" rails and bearings at the same place for about $10 - this set has 24" travel. So, I plan to reuse the bearing blocks later on the final build with longer rails, but for now will use both sets as is. Here is a pic of the rails mocked up with a 2" x 4" 8020 beam:
As far as controls go I have a complete conversion set up taken off an old Linde optical tracer burning table. A couple of years ago they retrofitted the machine with a Microkinetics controller assembly. I bought a 2 axis 80volt 10amp microstepping Driverack with their newer MN400 USB ready motion controller and a pair of 1625 ozin steppers and thier proprietary software for less than I could get a Xylotex controller for. I know a lot of people don't like the Microkinetics stuff, but I won't be out much if I don't like it and change later. For now it's a completely plug and play system.
On this first low buck build I'm going to use cheap acme allthread from McMaster Carr and homemade nylon engagement nuts. The final table will use rack and pinion, but for now the allthread gets me out of making reduction drives.
The plasma cutter is a 90amp Esab Power Cut 1500. Should be plenty of power! Be interesting to see if the HF start causes any interference issues. The THC on this build is going to be the good old floating head with a cone ramp around the plasma nozzle.
I got the control system in last week, and within an hour of UPS delivering had the motors spinning. Here is the stuff I got:
And some BIG steppers:
The big steppers are making me think about trying a direct drive approach. Yeah, i know it's not ideal, but trying to stay simple here! With 10x microstepping I could get the resolution around .001". And, these are strong, fairly low speed motors, so I'm not sure I'd even want to go with that much of an underdrive. They were running direct on the flame cutter they came off of.