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-   -   True Torque of a Servo motor for comparison to a Stepper motor, when used in a router (http://www.mechmate.com/forums/showthread.php?t=946)

Mcyoda Fri 15 August 2008 15:07

True Torque of a Servo motor for comparison to a Stepper motor, when used in a router
 
The servomotor is from Kelinginc model #KL34-180-90 with around 1125 oz/in peak.

Gerald D Fri 15 August 2008 20:57

1 Attachment(s)
From their spec sheet:


As far as we are concerned, that is only a 226 oz-in motor, and then only if you can feed it 7.8 Amps at 90Volts.

Mcyoda Mon 18 August 2008 19:26

Thank you Gerald for the clarification.

Gerald D Tue 19 August 2008 00:50

Posted by Marris on the Mach yahoo forum an hour ago:

1) Continuous Stall Torque: This is the most important specification
for getting the full life out of your motor. Do not exceed this value
except for very short periods of time.

2) Peak Stall Torque: Motor vendors tout this number because it looks
impressive. You use it for more than a few seconds and you will burn
your motor down.

3) Peak Stall Torque = 5 times Continuous Stall Torque. Usually. It
also means peak stall current is 5 times continuous rated current. At
5 times rated current, the motor generates 25 times more heat than it
can get rid of. That's why it will burn up.

4) Peter is right. Peak power is at 1/2 of peak stall torque. It is
also 2.5 times the continuous current and 6.25 times more heat than
the motor can get rid of. The motor will still burn up, only more
slowly this time. Peak power is OK if you are building an electric
torpedo. If you expect what you build to last longer than a few
minutes, it's not OK.

5) Max rated power is at 80% of no-load speed, called the rated RPM.
Rated RPM = No-Load RPM (1 - Continuous torque / Peak Torque). It is
the highest speed the motor can still deliver it's rated continuous
torque. Max rated power (continuous rated torque times 80% no-load
speed) is what the motor can put out 24/7.

6) You can burn a servomotor down at any RPM including zero RPM. Just
apply more than the continuous rated torque long enough and it will
burn down.


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