motor pulley sizing

motor pulley sizing

Postby coglesby » Wed Mar 25, 2020 4:36 pm

I have an Aries1 that has had the 300rpm motor upgrade and the 11.5" MK5 platter upgrade but the motor pulley was not changed to accommodate the 11.5" platter. Since I have the SDS I can adjust the frequency from 60Hz to 57.5Hz to speed correct for the 11.5" platter. Any reason to change the motor pulley?
AT-ART9 > VPI Classic 3 > VPI Aries (1) > Liberty B2B > Sansui G-9000 > GoldenEar Triton ones
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Re: motor pulley sizing

Postby Brf » Wed Mar 25, 2020 7:11 pm

Absolutely no need to change the pulley. A lot of users doing the exact same with excellent results. In fact, I did the same a while back with a former VPI table
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Re: motor pulley sizing

Postby jdm » Thu Mar 26, 2020 6:19 pm

I have a 300 rpm motor with 11.5 inch platter too. The speed is a bit fast using the lowest groove on the pulley so am curious if I have the correct one. Does anyone know the diameter of the appropriate pulley for this setup?

Jim
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Re: motor pulley sizing

Postby Brf » Thu Mar 26, 2020 8:16 pm

jdm wrote:I have a 300 rpm motor with 11.5 inch platter too. The speed is a bit fast using the lowest groove on the pulley so am curious if I have the correct one. Does anyone know the diameter of the appropriate pulley for this setup?

Jim

A 300 rpm/60hz pulley should have a diameter of approximately 1.285" for a 11.5" platter

Platter diameter = 11.5"
Motor speed = 300 rpm
Platter speed = 33.333 rpm
Belt thickness = 0.125"
Coefficient of expansion on the transverse axial of a Nitrile rubber drive belt = 0.5

Pulley size for a 300rpm motor with a 11.5" platter = [(11.5 +(.125)(.5)) x 33.333]/300 = 1.285"
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Re: motor pulley sizing

Postby jdm » Thu Mar 26, 2020 8:34 pm

Thank you brf. I will measure the pulley to determine if it is the right one. I could also try the PLC that came with the table but understand that it should sound better without it. I suppose there is only one way to find out.
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Re: motor pulley sizing

Postby Brf » Thu Mar 26, 2020 8:55 pm

jdm wrote:Thank you brf. I will measure the pulley to determine if it is the right one. I could also try the PLC that came with the table but understand that it should sound better without it. I suppose there is only one way to find out.


The PLC is not bad, it was just bettered by the SDS. What table?
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Re: motor pulley sizing

Postby jdm » Thu Mar 26, 2020 11:07 pm

TNT 2 with SME V arm.
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Re: motor pulley sizing

Postby jdm » Fri Mar 27, 2020 2:01 pm

I measured the pulley and it is 1.285" in diameter (using your method I calculated that the pulley for a 12" platter should be 1.34") so I do have the correct pulley. I can adjust the speed to 33.3 rpm with the PLC so will do some listening and determine if that is preferable.
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