Steve,
No secret - I ordered a Novakon Torus Pro Servo bed mill - 25"X x 15"Y x 12"Z travels, 2HP 3-Phase, AC servos, 500 IPM Rapids, ground ballscrews, linear rails on Z. Best of all, it's EASY to fully enclose, so first project will be fully enclosing it with 8020 and Plexi, and finally get to use the high-pressure (60 PSI) coolant system I've had sitting in the corner since I built it last year - WAY too messy on the knee mill. I will, very shortly, rip out the BOB and 86 Mach3, and put a KFlop in it so I can run my CNC controller app. This is the biggest machine I could find at a reasonable price, and the guys I've talked to that have them are VERY happy. It seems to be quite rigid, and very accurate. I hope to also add linear scales, fed into the KFlop, to get a bit more accuracy out of it by compensating for thermal errors.
Regards,
Ray L.