Finding Torque Without An Angular Acceleration (stepper motor)

AI Thread Summary
The discussion revolves around determining the torque required for a stepper motor to rotate a large thin disk made of 6061 aluminum. The user has the moment of inertia calculated but struggles to find the angular acceleration since the motor accelerates the disk to a near constant velocity and decelerates it almost instantaneously. Participants suggest consulting the motor's datasheet for torque per step and the time required for each step, as these factors influence performance. The user provides specific dimensions of the disk and the desired rotation of 40 degrees over 3.5 seconds. The conversation emphasizes the importance of understanding the motor's specifications to ensure it meets the torque requirements for the application.
Tyler
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A friend of mine posed a question to me the other day and I can't seem to wrap my head around it.

He's working with an electric stepper motor to turn a large thin disk, but he can't be sure of the torque required because to find the torque he needs the moment of inertia and the angular acceleration. The moment of inertia is easy to find since he has all of the disk's dimensions, but the electric stepper motor is taking the thin disk from 0 to a near constant velocity and back down to zero almost instantaneously.

Is there some other way to find the torque/angular acceleration that I'm just not thinking of?
 
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Tyler said:
A friend of mine posed a question to me the other day and I can't seem to wrap my head around it.

He's working with an electric stepper motor to turn a large thin disk, but he can't be sure of the torque required because to find the torque he needs the moment of inertia and the angular acceleration. The moment of inertia is easy to find since he has all of the disk's dimensions, but the electric stepper motor is taking the thin disk from 0 to a near constant velocity and back down to zero almost instantaneously.

Is there some other way to find the torque/angular acceleration that I'm just not thinking of?
What does the datasheet for the stepper motor say for the available torque per step? How many degrees is each step? The steps are not "instantaneous" -- the datasheet should give some idea of the time per step that is advised (depends on drive voltage and current)...
 
berkeman said:
What does the datasheet for the stepper motor say for the available torque per step? How many degrees is each step? The steps are not "instantaneous" -- the datasheet should give some idea of the time per step that is advised (depends on drive voltage and current)...
Well, therein lies the catch. He's trying to pick a motor based on the amount of torque he needs, or at the very least trying to verify that the motor he is looking at is more than enough for the task.
 
Tyler said:
Well, therein lies the catch. He's trying to pick a motor based on the amount of torque he needs, or at the very least trying to verify that the motor he is looking at is more than enough for the task.
Well, post links to a few of the datasheets he is considering, and we'll see if we can help. :smile:
 
berkeman said:
Well, post links to a few of the datasheets he is considering, and we'll see if we can help. :smile:
Sorry, could've sworn I put the link in the last post. My mistake.

http://www.newmarksystems.com/rotary-positioners/rm-8-motorized-rotary-stage/
Also, the thin disk being rotated is 6061 aluminum, 1/4" thick, 15" radius, and he wants it to turn 40 degrees over a period of 3.5 seconds.
 

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