HRX pulley upgrade

Re: HRX pulley upgrade

Postby Mr_Putty » Mon May 06, 2019 2:17 pm

Johnny,
Ok, let’s tweek your analogy. There is one motor (engine) at work, not two axels driven at different speeds (in a rear drive auto) So two tires, one new and one with half tread may be a better analogy. There are no axels fighting to take control, just one shaft ( for the TT motor). I doubt you would ever notice even a slight pull to one side while driving. In a front drive car I can see your concern with my analogy, but the end result is just a little more tread wear than ideal. The speed you drive is up to you. I’m not saying what I am doing is the ideal, but a temporary compromise I think is better. I might agree with you if I were using stock rubber belts, but I’m not. I use two EDPM o rings that are very well made. ‘-)
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Re: HRX pulley upgrade

Postby Brf » Mon May 06, 2019 3:13 pm

Mr_Putty wrote:Johnny,
Ok, let’s tweek your analogy. There is one motor (engine) at work, not two axels driven at different speeds (in a rear drive auto) So two tires, one new and one with half tread may be a better analogy. There are no axels fighting to take control, just one shaft ( for the TT motor). I doubt you would ever notice even a slight pull to one side while driving. In a front drive car I can see your concern with my analogy, but the end result is just a little more tread wear than ideal. The speed you drive is up to you. I’m not saying what I am doing is the ideal, but a temporary compromise I think is better. I might agree with you if I were using stock rubber belts, but I’m not. I use two EDPM o rings that are very well made. ‘-)


Mr_Putty, if it works for you that is all that matters, but we cannot ignore the physics of two belts, each being driven by a different pulley ratio, will attempt to drive the platter at dissimilar platter velocities. In other words, the two belts will fight one another for dominance. A gross example would be using one belt on the 33.33 pulley and the other on the 45 pulley in an attempt to drive the platter at 33.33 rpm.
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Re: HRX pulley upgrade

Postby Votan » Thu May 09, 2019 10:37 am

I totally agree with Brf that 2 or 3 belts on a standard stepped pulley will fight one another for dominance.
An idea (I haven’t try it) in making a standard stepped pulley (having diameter variances to each one of its grooves) to be appropriate for 2 or 3 belts:
What if on the pulley’s (while it rotates) grooves having the smaller diameter we apply some distinct layers of nail polish (each layer allowed to dry sufficiently) in making all of them to have the same diameter in the end?
This is of course for non USA VPI owners which (as me) can’t use the HRX pulley, because VPI manufactures it only for 60Hz/300 RPM (USA) motors, though for Europe the motors are 50Hz/500 RPM.
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