Looking for the right type of motor to suit a specific application

Other Hardware Motors, Mechanics, Power and CNC
1

Hello everyone,

I'm looking for a motor that will get its power from the grid and will suit the following needs:

  1. Use an Arduino to run.
  2. Carry a load of a metal disc with a weight of 500G
  3. Be able to reach fast RPM of at least a few thousands a minute or more.
  4. Have a way to know in which RPM the motor is running (would it have to have an encoder?)
  5. Be able to change direction instantly.
  6. The least complicated solution to setup and control.
  7. The least expensive it could be.
    I could compromise for the last two.

I am also looking for high torque (moment), not sure if #2 on my list covers it or not.

I was looking at brushless DC motors and servo motors but not sure which is the best solution.

I'll appreciate any suggestions or tips for what to look for.

Thank you so much.

Roy.

2

I have a few comments on your description ...

a motor that will get its power from the grid

[...]

brushless DC motors and servo motors

When I read the first line of this I thought you meant a mains-voltage motor, but I guess you just mean a motor that is powered from the mains via a transformer or equivalent. In other words, you don't want to use a battery.

  1. Be able to change direction instantly.

No motor can change direction instantly. How quickly (in milliseconds) do you want it to go from speed in one direction to speed in the other direction?

  1. Carry a load of a metal disc with a weight of 500G
  2. Be able to reach fast RPM of at least a few thousands a minute or more.

These requirements are pretty much meaningless without a good description of the project you want to create and, perhaps, a diagram of the proposed mechanism

...R

3

Robin2:
I have a few comments on your description ...When I read the first line of this I thought you meant a mains-voltage motor, but I guess you just mean a motor that is powered from the mains via a transformer or equivalent. In other words, you don't want to use a battery.
No motor can change direction instantly. How quickly (in milliseconds) do you want it to go from speed in one direction to speed in the other direction?
These requirements are pretty much meaningless without a good description of the project you want to create and, perhaps, a diagram of the proposed mechanism

...R

Thank you Robin,

Yes.. English is not my first language so that's what I meant.. I am not going to use a battery.

This is something about a physics experiment, I don't need it to be accurate as I also don't know what to expect while experimenting. anything can go.

for example by changing the direction instantly I meant maybe anything less than 500ms? anything faster than that would probably be much better.

In terms of RPM, it could be 1000 or 10,000 or 50,000, the other requirements (including cost) are more important, the higher it could go the better as I'd just like to experiment.

If there is a motor like that that could do all those things, I could just dig into the type it is and get one with the best specs which also has the most reasonable cost.

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It's not for this application of a saw, but this looks pretty good, running at 20,000 and can carry that metal disc.
So I just need something that could spin a 500grams disc easily (not a blade) and also to know at which RPM it is running.

Thanks again.

4

There are plenty of way to measure the speed of a rotating disc but that "instant reverse" requirement is going to stop you.

I don't think there is any motor that can be turning a 500gm disc at 20,000 rpm and then reverse direction, presumably to 20,000 rpm the other way, in less than 1/2 a second. Physics is against you, the accelerations required would be huge.

Steve

5

slipstick:
There are plenty of way to measure the speed of a rotating disc but that "instant reverse" requirement is going to stop you.

I don't think there is any motor that can be turning a 500gm disc at 20,000 rpm and then reverse direction, presumably to 20,000 rpm the other way, in less than 1/2 a second. Physics is against you, the accelerations required would be huge.

Steve

Thanks for your advice Steve,
So I could go for a lower speed or a lower weight.
Couldn't a large brushless DC motor used by drones achieve this?

6

roy777:
It's not for this application of a saw,

There are probably 1000 applications that it is not.

It will be much easier to help if you describe the 1 application that it is. Otherwise everyone's time (including yours) is wasted in guesswork.

...R

7

roy777:
Couldn't a large brushless DC motor used by drones achieve this?

Drone motors don't run in reverse.

A BLDC can potentially be reversed but it's the ESC that does the control and commutation that will cause you problems. Not many ESCs can be reversed and the software in most of the reversing ESCs wants the motor to come to a stop before it is reversed and that all takes time.

Steve

8

roy777:
Hello everyone,

I'm looking for a motor that will get its power from the grid and will suit the following needs:

  1. Use an Arduino to run.

You'll need an appropriate motor driver too

  1. Carry a load of a metal disc with a weight of 500G

Motors spin, they don't carry - you're omit all the important details about the mechanism
the motor is driving - all of this is important...

  1. Be able to reach fast RPM of at least a few thousands a minute or more.

Numbers, not adjectives, please. "fast" means nothing, "few" means nothing, "1000rpm"
means sometime, "five thousandths" means something - really people will have wildly different
ideas for "fast" or "few", you need to be concrete as possible.

  1. Have a way to know in which RPM the motor is running (would it have to have an encoder?)
  2. Be able to change direction instantly.

Not physically possible, you need to say how quckly, as a number!

  1. The least complicated solution to setup and control.
  2. The least expensive it could be.
    I could compromise for the last two.

I am also looking for high torque (moment), not sure if #2 on my list covers it or not.

I was looking at brushless DC motors and servo motors but not sure which is the best solution.

If you tell us what you are actually trying to do, that will make it tons easier to give sensible
advice. The symbol for a gramme is "g", not "G" (which means "giga" in SI). You did mean
500g in (2)? ?

I'll appreciate any suggestions or tips for what to look for.

Thank you so much.

Roy.

This is something about a physics experiment, I don't need it to be accurate as I also don't know what to expect while experimenting. anything can go.

Sorry, that provides no details at all... What is the motor driving? What mechanism? The
masses, shafts, levers, torques, gears, belts etc etc all matter in determining what speed and
power you require which are the fundamental first things that need to be determined.

for example by changing the direction instantly I meant maybe anything less than 500ms? anything faster than that would probably be much better.

That's glacially slow to me :). That sounds a plausible value if the mechanism is small with low M.o.I., but
still need to know such details to say more.

In terms of RPM, it could be 1000 or 10,000 or 50,000, the other requirements (including cost) are more important, the higher it could go the better as I'd just like to experiment.

50,000 rpm will not be reversible in 0.5s, unless its a tiny tiny motor. KE goes as the square of speed.