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 phy1970 22nd February 2012 02:54 PM

Michell platter diameter

Hi

I am working on a new platter to my Michell Gyrodec bearing.
I would like to drive i with the original Mirchell motor, so I would like to know if anybody can tell me the exact diameter of an Michell Orbe platter or an Gyrodec platter, where the belt drives the platter...

Peter

 Nanook 23rd February 2012 02:14 AM

all you need to know

is the speed (RPM) of the motor, and the frequency of your domestic supply (North America is 115 VAC, 60 Hz...). Then measure the belt pulley on the motor accurately. Then measure the diameter of the platter or sub-platter at the location of the "driven" portion of the platter or sub-platter as is the case. If you have a 60 Hz motor, it is most usually a 300 RPM type. The ratio of the motor speed to platter speed is the drive ratio. If a 300 RPM motor, and the platter spins at 33-1/3 RPM, then the ratio is as follows:

300: 33-1/3
300:100/3
900:100
9:1

so for every 9 turns of the motor, 1 turn of the platter occurs. Now look at the diameter of the pulleys and do a ratio of those. Say the motor pulley has a diameter of 11 mm Then:

9 (revs of the motor) × 11 mm= 1 (rev of the platter) × diameter of the "driven portion of the platter or sub-platter. In this case the diameter of the driven portion of the platter is 99 mm. This little bit of math does not take into consideration any possible belt stretch which should be. But dimensions and material of the belt should be known.

What type of motor is the motor an AC (early) or a DC (late) one?

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