Go Down

Topic: motor for fast stop/run frequency turntable (Read 89 times) previous topic - next topic


I want to build a turntable with a 40 to 50cm diameter (ca. 15-20 inch), and a load of about 1 - 2 kg.

The table should make 360° in 1 Sec. Not in a continuous rotation, but with 25 ‚stop an goes'. Each stop should be at least 30ms (x25). So the motor should turn the 360° in 250ms, or each 14.4° in 10ms.

I've tried a setup with arduino, big easy driver and a stepper with planetary gear stepper specs. The specs for the motor are 904 rpm, but I only managed to run the 14.4° in 30ms. Besides the whole thing is really noisy and vibrates and jumps a lot, obviously because of the fast stop and go and the centrifugal forces.

Does anyone have a suggestion, what motor would be most suitable: a stepper or would a brushless motor or servo be a better option? What driver would I need?



First do the maths....

You want to accelerate and then decelerate going 2pi/25 radians in 1/25th of a second

Just the acceleration takes you pi/25 radians in 20ms, and w = 0.5 a.t^2, gives a = 628 rad/s/s.

Lets say your turntable weighs 1kg, with even density, radius 25cm.  Then its MoI is 0.25 M R^2,
or 0.0156 kg m^2.

torque = MoI x angular acceleration, ie 628 * 0.0156 = 9.8 Nm

Peak angular velocity is 0.02 x 628 = 12.5 rad/s (120 rpm).

torque x speed = 122W peak mechanical power required.

So you need a servo motor of 150W or more.  Yes it will vibrate like crazy, because you
are vibrating it like crazy...

So what are you actually trying to do?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Go Up

Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

via Egeo 16
Torino, 10131