Electronics > Beginners
Best Motor For Driving A Lead Screw Assembly
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MattyT:
How do choose the correct stepper motor?
I'm looking at NEMA stepper motors which are small, compact and lightweight, but the speeds are obviously different depending on which motor I choose.
So I know I need to consider my torque and speed requirements but to do that, where do I find the motor's torque-speed curve to select a motor that will do the job.
Rerouter:
Provided you have not gone too far down the ebay rabbit hole, most nema stepper motors should give a torque curve vs speed at a known drive current.

Suppose starting backwards, what application is the lead screw being used for, is it actually a lead screw or a ball screw or acme screw etc, this effects the "efficiency" of the motor power to be delivered,

Your top speed will be mainly limited by friction from the rest of the setup vs the torque the motor can provide without skipping steps. You can cheat this a bit if you trim in your acceleration / deceleration rates, so your not fighting static and rolling friction at the same time.
Doctorandus_P:
First calculate your speed / torque requirements, and decide if it fits within the range of a stepper motor.
(With stepper motors usefull torque tends to fall a lot abouve 600rpm).

If your lead screw only needs to rotate very slowly you can add some gears or a timing belt, which results in less needed torque for the (stepper) motor.

Then go to some site where you can buy stepper motors, get some datasheets and see if they fit your requirements.
If the first fails to meet them, get a datasheet of a bigger motor, if the motor has muh more torque capability then you need, get a smaller motor.

"Usefull" torque of stepper motors also depends a lot on the quality of the motor driver and the supply voltage for that driver.
Steper motors & driver combinations with built in position feedback are also becoming more common nowaday's.
With position feedback you need less torque reserve for the motor, which can result in a smaller motor, which pays for the feedback components. With position feedback the driver also dynamically adjusts the motor current, which results in higer efficiency and less mechanical vibrations and noise.

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