That isn't want it needs to turn, that is what it needs to turn at the absolute maximum speed. You can use higher inductance motors at a lower voltage and have a working CNC machine just fine... it just may not go as fast as it would with a higher voltage. But you will hit the motor heating limit or the total wattage limit before you hit the voltage limit in any case.

The Linistepper is a great design (arguably the best) for a system up to 75Watts of power. E.g. 2 amps per axis at 35 volts. They require a larger heatsink than most drivers, but then the motor will stay cooler, and they cost more than the TB6560 drivers, but they are easier and much cheaper to repair. 75 Watts will generally move a 40 lb load at 1000 IPM... given a good lead screw and a smooth axis.

Watts = ( IPM * Lbs ) / 531

Or

Watts = (Inch/Ounces * RPM)/1351

If you need more than 75 Watts, up to about 120 watts the SLAm Stepper Motor Controller is a good option. It isn't as smooth as the Linistepper, and it cost more to repair, but it does provie real power.

Those are both Unipolar, which isn't as bad as everyone says. Unipolar means less starting torque, but slightly higher top speed, which is usually more imporant for CNC anyway.

We will have a new driver out soon that will do 4 amps at 48 volts (192 Watts) and is bipolar, and is about like SLAm as far as cost and repairability. Eh... a little more than a SLAm probably.

If you need more than that, seriously, buy one of the low end Geckos for $80. You won't regret the extra cost.