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masterwigglestin

Feb 01, 2013, 09:25 pm
I am working on a project which will need an as small as possible DC motor which will spin up to 2500 RPM with a little bit of weight on it, maybe a pound. I don't know a ton about how to pick out the right motor and will need a speed controller too so that I can control this setup with my Arduino. Thanks.

MarkT

#1
Feb 02, 2013, 01:52 am
Motor load is a torque, not a weight - you'll have to explain more about the mechanics of the
situation or work out the torque yourself.  If none of this means anything then just provide
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

masterwigglestin

#2
Feb 04, 2013, 05:16 pm
It is for a centrifuge. I am planning on attaching a plastic disc directly to the motor shaft.

JimboZA

#3
Feb 04, 2013, 05:31 pm
It's aaaaaages since I did this kind of calculation, but the torque T required depends on the Moment of Inertia I of the disk and the required acceleration a, and :

T = Ia

The Moment of Inertia of a disk on mass m and radius r is

I= mr2 / 2

(Let's check those units....

units of I will be kg m2
units of a are rad / s2 or just 1/s2

So units of T are kg m2 / s2

(Which is right since T=Fd and units of force at kg m / s2) )

I think... it's been a long time, as I say

Johannesburg hams call me: ZS6JMB on Highveld rep 145.7875 (-600 & 88.5 tone)

encryptor

#4
Feb 05, 2013, 11:19 am
I believe you'll want to know the horsepower of the motor.

JimboZA

#5
Feb 05, 2013, 01:35 pm

I believe you'll want to know the horsepower of the motor.

Power in Watts is just P = Tw where w (lower case omega) = rotation speed in rads / sec

Johannesburg hams call me: ZS6JMB on Highveld rep 145.7875 (-600 & 88.5 tone)