Comments sought on new build: A CNC Router for RC Gliders and Planes

[Jonathan]

I reckon they're both right :) Jonathan's calcs are ok if you are not microstepping cos then you have to derate the torque significantly not to lose steps, so Dean's answer is pragmatic in the likelihood you will be microstepping.

Microstepping reduces the so called 'incremental torque' - i.e. the torque available to move from one microstep to the next and hold a microstepped position - the torque when the motor is moving continuously (i.e. the operating point I calculated) is the same regardless of microstepping. Also above low speeds stepper drivers switch to full stepping.

Personally I would still use two motors, but for other practical reasons - not due to the torque rating.