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Topic: spin a big and heavy disc with a motor (Read 119 times) previous topic - next topic

LimuloLab

Hi guys,

I'm facing a problem here and I'm not so experienced in working with motors and drivers. My only experiences are with little vibration motors, motorized potentiometers, steppers and little more. I work with Arduino.

Now I'm working on a project where I need to spin a big wood disc. I don't need to make it spin fast, in fact it will be suffient to accelerate it reaching a frequency of 1 complete round every 2/3 secs.

I've made experiments with a EMG49 motor and a Pololu High-Power motor driver 24v23 CS.

I've powered the driver with a 12V power supply able to feed 10A and I was perfectly able to make a little prototipal disc (diameter 70cm and a weight of 8kg approx) accelerate, spin and decelerate very well, even if I was driving the motor at half of its voltage and also with a little duty cycle PWM.

The definitive disc has a mass of approximatively 16 Kg with a 110 cm diameter.

Do you think it will be possible for the same motor/driver configuration to move the definitive wood disk?

In case not, would you be so kind to link me some motors and drivers with these capabilities (it should be relatively easy to connect it to and Arduino).

Thank you very much for your patience and support

Paul_KD7HB

Why not weight down your test disk and find out?

Paul

LimuloLab

Hi Paul_KD7HB and thanks for your reply.
Yes for sure I will try to add some weight to my prototipal disc in order to read the definitive weight and see if the motor/driver configuration will still be working.
I posted here in order to ask for someone with experience with similar situation.

In case it will not work I'll have to buy a new motor/driver and I've no experience on what kind of torque and other physical characteristic I have to look for.

jremington

#3
Aug 26, 2019, 06:02 pm Last Edit: Aug 28, 2019, 03:52 am by jremington
Quote
it will be suffient to accelerate it reaching a frequency
To calculate the required torque, you must define the time to accelerate to final speed.

The motor must also be able to overcome friction. Is the disk spun on ball bearings?

Ignoring friction and assuming the mass of the disk is uniformly distributed, the disk moment of inertia is 9.7 kg m2.

If you accelerate the rotation rate from zero to 9.5 radians/sec in 10 seconds, the torque required is 0.95*9.7 = 9.2 kg m2/sec2 = 9.2 N-m, or 94 Kg-cm.

Paul_KD7HB

Experience is not necessary, but the ability to do some math is.

Paul

LimuloLab

Thank you Paul_KD7HB,
I totally agree with you: so I'm waiting for the mathematical formulae I have to use to calculate the torque of a motor knowking the weight of the disc and the acceleration speed.

Do you know these formulae? Can you help me?
Thanks

jremington

#6
Aug 26, 2019, 06:22 pm Last Edit: Aug 26, 2019, 06:25 pm by jremington

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