Originally Posted by
rowbare
As Jim said, the torque curve on a servo motor is pretty flat. Since power is a function of torque and speed, the slower your motor is turning, the less power it is putting out. This affects how much metal you can remove in a given amount of time.
For instance, the rule of thumb for steel is that you can remove 1 cubic inch per minute per horsepower. So your old lathe could remove about 1.5 cu/in per minute at any speed. With the new 3 hp servo, you can remove 3 cu/in per minute at the rated speed but maybe .1 cu/in per minute at the low end using the 30-1 ratio you mention.
If you can do it. I would recommend a two speed setup.
bob