Rather glib title I know but the the thread is a serious one.


I've pretty much decided to go DMM servo (Nema 23 equivalent) when putting together a CNC setup I'm considering.

For all the reasons you might expect, speed, accuracy, smoothness, noise etc but reading the forum, there are some clever people here who squeeze as much as possible out of steppers despite their weaknesses, and get great accuracy, speed etc. So I was wondering if there is any gotcha to put me off DMM servos (or servos in general)


They will be driving a gantry from between 60-80kg,

Y (2x) 16x10mm BS 1330mm
X 16x10mm BS 1040mm
one motor each, both driven nut via belt 1.25x reduction, fixed ends
Z 16x5mm 1:1 ratio 190mm


Doing some rough calculations, Y inertia ratio will be between 2-4x. Possible rapids at 900-1200IPM.... which covers the Y in under 3 seconds, scary stuff.


I might add a laser at some point, so I think speed and accuracy would be advantageous but at the cost of at least £1500* (damn you import costs), vs 3x low inductance steppers, 3x good drivers, approx £250-£500, the servos better be amazing.
Envisaged material: wood, non ferrous.
(*both not including motion control)

Thanks all.