Servo motor Torque curve?

[flash319]

So I am very well into my 4X10 servo controlled table. I have all the controls done and am just slowly buying the last parts for the cross axis (4 foot direction). I am using 2 THK rails holding my Z assembly. I have a 750 watt, 5000rpm Allen Bradley motor for driving this axis with a belt.

My question is what size of pullys to use on the belt? The Z assy has a bit of resistance to it as I am using SRS 25 type bearings and the rails. I have a 5:1 reducer that I can put on the motor if I need to. I am not a CNC machinist so I am not familiar will cutting speeds.

I was thinking about putting the reducer on and running 1.5" pullys? This would give me 4.7 inches per turn. This seams very fast and not using much of the motor. Is the torque curve fairly flat on a AC servo motor?

[ger21]

To take full advantage of the servo, gear it so at your rapid speed, it's spinning at about 80% of it's max, or about 4000rpm

[flash319]

What speed is standard for a rapid?

[jdell42]

For a machine that big you would want to have a rapid speed of 200 at a minimum. Even then it is going to take you 30 seconds to get from one end of the table to the other.