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

[irving2008]

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.

[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.

[Neale]

I've just about reached the stage on my machine where I have to decide one motor/twin belts or two motors. Sounds like the received wisdom is to go two motors. So, that means buying one more motor, another driver - but the old analogue ones I have at present are obsolete, so that will mean two new digital drivers, and, what's worse, ditching LinuxCNC and having to use Windows/Mach3 to be able to home two motors, and, probably, an external motion controller. Ho hum...

[njhussey]

I've just about reached the stage on my machine where I have to decide one motor/twin belts or two motors. Sounds like the received wisdom is to go two motors. So, that means buying one more motor, another driver - but the old analogue ones I have at present are obsolete, so that will mean two new digital drivers, and, what's worse, ditching LinuxCNC and having to use Windows/Mach3 to be able to home two motors, and, probably, an external motion controller. Ho hum...

I'm in a similar situation regarding the single vs two steppers, I can either buy another Nema 23 3Nm stepper and driver (but mine are the AM882 so I'd have to source from China or ebay) or a Nema 34 and 240V driver...decided on the Nema 34 for a bit of safety margin...