Ultra low cost servo system, found motor, amazingly strong.
How to make a stunning strong axis for a huge 3D printer or CNC machine for less than $50:
1. Pull a decent sized DC motor from some old office equipment, or industrial recyclers. This one was free for some effort.
2. Buy and solder up the MassMind servo control system:
http://techref.massmind.org/techref/i... under $50
3. Add to your power supply and motion controller (RAMPS/Marlin, GRBL, PoKeys57CNC, whatever)
Tune the PID via an USB-serial adapter (like the Massmind RLC-3, FTDI, whatever), and away you go! (tuning video later)