The stock motor on the Taig CNC-ready mills is 1/4 horse power and spins at 3450 RPM.
Horsepower = Pound force feet * Rotations per minute / 5252
0.25 = Ft-Lbs * 3450 / 5252
1313 = Ft-Lbs * 3450
1313 / 3450 = Ft-Lbs
Ft-Lbs = ~0.381
~0.381 Ft-Lbs = ~0.516 N·m
So, it looks like the Taig 1/4 hp motor has ~0.52 Nm of torque.
After looking at the Keling motors again I've decided the smaller, lighter, and faster KL34-150-90 (NEMA 34) is a better choice. Its constant torque is 0.84 which is roughly 58% more powerful than the 1/4 hp AC motor. A decent jump, but nothing crazy. Also, it's top speed is 6000 RPM, which will allow a smaller pulley to be used on the motor, which will allow it to be moved closer to the spindle, which will probably reduce the strain on the Z column.
Keling only offers 2 encoders (a 200 and a 500 CPR quadratic). 6000 RPM is obviously 100 rotations per second. At 100 RPS a 200 CPR quadratic encoder will be pumping out 80,000 pulses per second! (100 x 200 x 4 = 80,000)
80,000 is already pushing the limit of what my Mach3 install can handle (100,000 pulses per second AKA 100Khz). So, that means I'll have to use the Gecko g340 servo drive (or find some other drive, which I have little interest in doing) so I can reduce the pulses by 10, bringing the new total pulses per second down to 8,000. Well, that give me a lot of working room. Using the same math I can now step up to the 500 CPR encoder that will put out a maximum of 20,000 PPS, a number I'm comfortable with.
The g340, motor, encoder, and cable are $324.50. The only 72v power supply I see for sale anywhere is the Keling KL- 7212, which is $149.00. Total for this setup: $505.34 shipped. I'm pretty much going to jump unless