But, for the spindle alone, we can use the 50V controller above, which I hope will be more reliable than a hacked rc esc. ;-)

Monroe, I think realistically, using the DC1 closed loop, with perhaps an upgraded high voltage spindle sounds doable.  I looked at the sketches that the DC1 system uses, and they are very basic, with no software filtering on the encoder.  Hopefully, the encoder chip, is reliable and does its magic.

Monroe, here's a description of that DQ542MA stepper controller:

 l DQ542MA with 4.2A peak current, 50VDC voltages, 128 Microstep

  DQ542MA is a type  of two-phase hybrid stepping motor driver, the drive voltage of it is from 18VDC to 50VDC. It is designed for use with 2-phase hybrid stepper motor of all kinds with 42mm to 86mm outside diameter and less than 4.0A phase current. This circuit that it adopts is smiliar to the circuit of servo control which enables the motor run smoothly almost without noise and vibration. Holding torque when DQ542MA run under high speed is also significantly higher than the other two-phase driver, what’s more, the positioning accuracy is also higher. It is widely used in middle and big size numerical control devices such as curving machine, CNC machine, and computer embroider machine, packing machines and so on.

Does it sound like open or close to you?

The best bang for the buck is this package, using the DQ542MA motor driver.  If the DQ542MA is closed, then I think we have a candidate.  But, we're still talking ~$800 for 6 motors and controller.

http://www.ebay.com/itm/6-axis-CNC-controller-kit-425oz-in-and-1600...

Oh well, look here's a used 3-axis servo controller with encoder, motors:

http://www.ebay.com/itm/SAMSUNG-400W-SERVO-PACK-DRIVER-MOTOR-3-AXIS...

But, it's used for $1349.99.   I guess that's the kind of system we want, but new would be too expensive.

I really like that DQ542MA system.  All standard NEMA motors, should be easy to replace, add one DC1 for the spindle motor, and I think we can have a good system.  They even sell the same system with only 3 axis NEMA23 motors for about $300, shipped, for the basic system.

Yes, I'd like to see this come to fruition. Monroe has big plans.  

In fact if we do our own CNC, I don't see why we can't just swap the spindle for a hot end, and turn it into a 3D printer too.  Monroe is thinking of a machine with pretty high Z travel.

@Ellison, that would be awesome. I hope Monroe's plans would be inexpensive, so that we could build one with 3D Printer capabilities (swap) as well.