How much weight I can spin on a motor?

[HavitShelYain]

TL;DR Summary

I would appreciate the help!

Hi guys,
I don't have much knowledge of physics sadly, and I want to build a machine that can spin a disk.

My question is - How can I know the weight I can spin on a motor?

I need to be able to spin around 5-6kg, for 350 RPM, and I'm not sure I'm aiming for the correct motor.

I'm thinking of a 1HP, 1730 RPM motor, that I can slow down to get to the correct speed.
(https://www.ebay.com/itm/353221688661?hash=item523da73d55:g:ONQAAOSwK2Zfde67)

I've done some calculations, but I'm not sure I know exactly what equations I'm supposed to look at. Also, I don't know how to calculate the acceleration of a motor.

I would really appreciate the help, and I hope this is the correct place for me to ask these kind of questions.
Thanks!

 

[berkeman]

Summary:: I would appreciate the help!

I don't have much knowledge of physics sadly, and I want to build a machine that can spin a disk.

My question is - How can I know the weight I can spin on a motor?

I need to be able to spin around 5-6kg, for 350 RPM, and I'm not sure I'm aiming for the correct motor.

Welcome to PF.

If you can give more details of the load (shape, dimensions, orientation, etc.) that would help. Also, what kind of bearings are you planning on using? What is the application?

 

[jack action]

You need to know the friction power of your system. For example, if you use roller bearings, the manufacturer can help you with that.

You may have additional friction torque on your system (a knife cutting on your part, for example).

If acceleration is important (how much time it takes to go from 0 to 350 rpm), you must consider the rotational inertia as well.

 

[HavitShelYain]

Thanks!

It will be a round shape, I can show you a picture of what I imagine it should look like.
The wooden circle is supposed to be 23" diameter.

Like jack said, there is additional friction torque on my system, I'm not sure how to measure it though.

The acceleration is not important, I don't mind waiting before it gets to 350 RPM.Also, I'm planning on using pillow block bearings.

 

[jack action]

Maybe this calculator will help?

 

[jrmichler]

Assuming that you are trying to do some of the stuff shown at lancecampeau.com, here are some suggestions.

While a 1730 RPM motor can be slowed to 350 RPM using a variable frequency drive (VFD), you are far better off to reduce the speed using a speed reducer. A good speed reducer for your application is a V-belt drive with a 5:1 speed ratio. That will give you exactly the 350 RPM you want, plus it will multiply the torque by 5 times. Without the speed reducer, it might not have enough torque to meet your needs. You can still use a VFD to get additional speed control.

Using a 1/2" V-belt, a 2" pulley on the motor, and a 10" pulley on the driven shaft will get the ratio you want. A 1/2" V-belt normally requires a larger pulley than 2", but a 2" pulley will work well enough in this application. These size parts are readily available at low cost. A 3/8" V-belt would work even better on this small pulley.

I suggest using a shaft at least 3/4" diameter.

 

[HavitShelYain]

Thank you guys!

jrmichler, so you suggest using a v-belt drive, that's sounds great, thanks for the input.
But using those numbers, how do I know how much weight can I put on the motor? could 5-6 kg work?

Jack, I'm not sure exactly how to fill in the calculator you sent, there are many variables I'm not familiar with. (Machine Coefficien, Feed per Revolution, Specific Cutting Force)

 

[berkeman]

But using those numbers, how do I know how much weight can I put on the motor?

Hopefully you understand how the bearing configuration matters, right? What are thrust bearings, and when are they used?

 

[HavitShelYain]

I don't, sadly.
Can you point me to a good place to get that information?

What do I need to look at regarding bearing configuration?

And are thrust bearings are more suitable for this application then pillow block bearings?

 

[Baluncore]

It will be a round shape, I can show you a picture of what I imagine it should look like.
The wooden circle is supposed to be 23" diameter.

Are you building a “metal spinning” lathe? If so, the power needed will be the force applied * friction coefficient * speed * radius of the work. For large flat items you will need lower RPM. For small items higher RPM. That suggests you will need cone pulleys for your 'V' belts so you can change the speed for different working radii.
https://en.wikipedia.org/wiki/Metal_spinning

 

[jrmichler]

ASSUMPTION: I'm assuming that the OP is doing the type of things shown at lancecampeau.com. The loads are light, the speed requirements modest, and the required precision is comparable to that needed for a wood lathe.

Pillow block bearings will handle modest thrust loads. I once built a wood lathe using pillow block bearings for the headstock. It worked very well.

The drive I suggested will be sufficient to spin 5-6 kg at 350 RPM and do the sort of light work shown at lancecampeau.com.

 

[HavitShelYain]

Yes, I intend to do the type of things shown at lancecampeau.com. for another demonstration -


So just to make sure - a 1730 rpm reduced to 350 using a V-belt drive, 1HP motor will be able to spin 5-6 kg of material, considering the diameter is 23"?

Baluncore - it will always be large flat items. the diameter of the wooden circle, which I'll put the metal on, will always be 23".
The metal on top will range from 14" - 22".