What electric motor do I need to rotate a platter that weighs 6 - 10lbs?

[Billygibson2]

Would a DC motor that had torque of 0.34 Nm be able to generate enough power to rotate a platter that weighs 6 - 10lbs

 

[Baluncore]

Welcome to PF.
I guess it would be able to accelerate the platter, and then overcome friction when running.
The motor does not generate, it converts electrical energy into motion energy and heat.

 

[Billygibson2]

I am not an engineer, and even far from an electrician, but I'm working on a project that spins a platter it holds about 9 lb and I need to build up enough speed to go only 40 to 60 RPMs with the platter. like I said about 9 lb total. Thank you for the note, and for any additional information that you can give me.

 

[Baluncore]

The distribution of the mass on the platter will determine the rotating inertia, and so how long the motor takes to accelerate the platter.

The torque from the motor will be proportional to the motor current.
With good bearings it should take little energy to keep things turning.

Will you have a speed reduction between the motor and the platter ?
How will you regulate the RPM once you get it spinning ?

 

[Billygibson2]

As I am building this product, I am now finding the different things that I am incorporating to it. I've added a speed controller but I really need the proper motor to use. I have a DC 100w scooter motor I'm going to use, I was told that it had 0.34 Torque, and I wanted to know if I'm on the right rack with the motor I purchased?

 

[anorlunda]

Will you attach the motor's shaft directly to the turntable shaft? Or will you use something like this belt drive?

Or perhaps one where the motor shaft rubs against the turntable rim?

Key parameters are turntable RPM? motor RPM?

 

[Billygibson2]

Will you attach the motor's shaft directly to the turntable shaft? Or will you use something like this belt drive?
View attachment 296805
Or perhaps one where the motor shaft rubs against the turntable rim?
View attachment 296806

Key parameters are turntable RPM? motor RPM?

I am using a chain not belt, and the shaft would use gears to generate rotation of the platter, but thank you very much for your help.

 

[anorlunda]

I am using a chain not belt, and the shaft would use gears to generate rotation of the platter, but thank you very much for your help.

The power needed can be determined by either:

1. Accelerating the turntable and motor from stop to full speed.
2. Overcoming friction at full speed.

Adding gears adds more friction. Potentially, gears are the dominant friction. Friction is something that can't be easily calculated. You have to determine it by experiment.

In terms of acceleration, the weight and shape of the object on the turntable does matter. Most difficult is starting from zero speed. The motor needs good starting torque.

So the bad news is that it's hard to calculate exactly what you need.

The good news IMO is that a scooter motor should have good starting torque, and it is likely that the running power and torque far exceed what you need for the turntable. The penalty for having a motor stronger than you need is almost zero. So go for it.