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« on: September 22, 2013, 12:00:35 PM »
Servos and steppers are two very different animals. Steppers produce their max torque at stanstill (Holding Torque) and it drops away with speed, quite rapidly after a few hundred RPM usually. A servo on the other hand normally is rated for constant torque and peak torque. The Constant torque is what the motor can produce constantly from zero RPM right up to Max rated RPM. In addition Servos have a big overhead for short periods, usually 2 to 3 times the constant torque.
For a Bridgeport sized machine I would think 750Watt AC servos would be more than adequate at 2:1 reduction, some people reckon even 400W would suffice although I am not so sure about that, suppose it depends what you will be doing and cutting and what accel and Vel you are wanting.
There are currently Samsung 750W drives, motors and cables on eBay, they are second hand obviously and they are asking, if I recall correctly, about $1800 for the three sets and 400W ones for about $900.
Hood