Quote:
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Originally Posted by Greg Needel
... How do I determine the required torque rating of the motor?
take the force (5lbs) at the point of most stress (45 deg) and
[[[[multiply the distance from the orgin * the sin(45deg) * the force (5lbs) ]]]this will give you the moment about the rotation of the motor which is the exact torque needed at that point. so get a motor that is at least that strong ...
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Woah Greg, hold on a minute ...
The maximum torque required will be at the point where the force normal to the arm is maximum, which would be in the horizontal position. Max torque required for this application will be the 5lbs X arm length
<edit>PLUS the mass of the arm multiplied by the distance from its cg to the pivot point
</edit>.
Also Erik, you should make sure your motor has enough power for the speed that you desire. If you multuply the max torque number from above (in foot-pounds) by the maximum angular speed that you desire (in radians/sec)
<edit>then divide by 550
</edit> you will get the power required in horsepower.
Of course these torque and hp numbers would be the minimum required motor ratings assuming perfect (frictionless) conditions so I would suggest to also increase these numbers by a significant safety factor, maybe 50% (multiply by 1.5).
Hope this information is helpful.