 # Need help with Motor torque requirement

Hi, guy

I am planning to build a base to let me LEGO sits on top, and my LEGO weight 10kg. building the wood base is easy, but i want base to be rotate with a motor. so i am not sure how to select the right motor for my base.

assume the base is 8in diameter and 85% efficiency

from what i know T=F*R =98N *0.2m =19.6 N-M

so in this case i have to look for the motor that handle that much of torque?( my math maybe wrong )

The force is axial, not tangential, there is only friction to overcome.

Having said that friction will depend on the weight on the turntable, but also on the bearing system involved.

You also have to consider the angular acceleration and moment of inertia of the table and load as you'll need torque to accelerate too.

Do you have an idea of how you are going to provide bearings for the table?

MarkT: The force is axial, not tangential, there is only friction to overcome.

Having said that friction will depend on the weight on the turntable, but also on the bearing system involved.

You also have to consider the angular acceleration and moment of inertia of the table and load as you'll need torque to accelerate too.

Do you have an idea of how you are going to provide bearings for the table?

no, i dont. any suggestion?

on the motors i found. they are around 50 oz-in. will them work on this case assume we have less friction

thanks

Does the motor have gear reduction? How many RPM?

That's 0.36Nm in sensible units. No way to tell without measurements from the table really - suggest you build that first and then measure the torque, double it and search for a (gear)motor...

Consider the torque needed, consider the max angular velocity (speed), and decide what angular acceleration will be good enough. With an idea of the turntable radius its possible to estimate the worst-case moment-of-inertia of a 10kg lump covering it which would be a useful figure to have. Moment of inertia goes up rapidly with radius.