Rek-O-Kut pulleys

[dobias]

Are there any 78 rpm & 45 rpm pulleys available for the Rek-O-Kut N-33H turntable?
If there aren't any available commercially, is it possible to have them made.
I'm assuming the 33 rpm pulley is removeable, or is it a press fit?
I was ready to buy an N-33H until I was unable to find any alternate pulleys.

An interesting eBay BIN offering shows a nice looking N-33H with a loose belt laying next to it & it had never been powered up by the seller. Upon close examination of the picture the platter is curved & not flat on the perimeter... wrong platter ? I'm not going to gamble on that one.

[pjanda1]

I'm fairly certain that they all had curved platters. My belt drive ROK does, as do those that I've seen in pics. The belt migrates to the widest point it can, so it isn't a problem (and might be beneficial) from the standpoint of speed stability. It does mean that whatever pulley you put on the motor must align with the highest point of the platter. Be not afraid, they are very well built machines!

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

[dobias]

Paul,
The photo of your drive motor looks as if the shaft diameter is actually the 33 rpm pulley. Is that correct or an optical illusion? Is the Pulley end removeable?
I'm still struggling to come up with 78 & 45 rpm pulleys. I'm coming to the sad conclusion that it's a lost cause.
Frank

[pjanda1]

Yup, the motor spindle (which given the way the papst motor works, ain't your typical spindle arrangement) is actually the pulley. It is only removable in the sense that you can take the motor apart, and you'd have to press it out. I'm not sure if it could be pressed back in perfectly straight, but then I don't know that much about such things. I think some ROK's came with another step for 45 operation, but I'm not sure how it worked. Perhaps you'll come across a pic somewhere.

Either way, given that the spindle is nice and straight, getting pulleys machined for 45 and 78 operation should be really simple. I suspect there would be some measuring and math combined with some trial and error to get the speed just right. You could either have a machine shop make it a little big and shave it bit by bit until it was just right, or you could have a few sizes made. The Papst motor probably has enough torque to pull several platters, so it shouldn't have a hard time spinning it at 78 rpm.

If you were having pulleys made, it'd be the perfect way to go with a thread drive setup. I don't know if you've read about it over at AA, but the folks that were doing that would use heatshrink to make a "pulley" until the found the right spot on the crowned spindle for the perfect speed. Then they'd have a shop make a pulley that diameter.

Of course the ideal, but not budget, option would be Mark Kelley's motor control. Then you could run it any speed you want!

Paul