and they recommend the 280 oz-in model for the G540. G723-280-4 Stepper Motor
To me, that machine you're building (48" x 36" moving gantry) sounds a bit large for that motor, or that drive. If it were me building it, I'd be looking at some of Gecko's higher voltage drives, and maybe one of their 400 oz-in motors - either that, or going with NEMA 34 frame stepper motors. But you might ask around among the G540 enthusiasts, and see what sort of luck they're having running that big a machine on it with 23-frame motors - who knows, it might work fine...
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