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Sunday, June 20, 2010

Turntable spindles and bearings: grease or oil, science or magic?

Wish to share (part of) a recent conversation still on-going with MJ, a Canadian friend, very well informed, almost "obsessed" and passionate enough to quite deeply understand the several parts which compose the puzzle.

"I think that a TT bearing lubricant must provide a conductive path for static charge build up. That way the charge at the stylus tip can flow to the platter then to the bearing and finally to ground. This presumes that you provide a path from the disk surface to the platter surface to the bearing asembly.
Yes no matter what material you use for the bearing assembly there will be compression and deformation in the metal parts. Lubricants not only provide for a no metal to metal contact and low friction but they also provide damping to the system.
I spoke with an application engineer at the HQ of Power Up Lubricants. I asked him to explain how moly type lubricants work. I had been under the impression that they worked into the metal surface and bonded there filling in any small surface irregularities in effect leaving the surface smoother. That is not the case. Moly products actually form a molecular matrix which envelopes the structure. Should there be any impact that coating can crack anf break open which then leaves the equivalant of a rough spot untill the moly components rebuild which takes some time to do. Your graphite infused lubricant while not as slippery as a moly product does not suffer the same issue as the moly as it does not encapsulate the metal surface. It simply provides a layer of slippery graphite and there is never any chance of roughness as with the moly. I will say that if a bearing is left undisturbed the moly product should work very well. But my impression is that the moly while slippery than graphite will not damp as effectively as the graphit. I would guess the graphite would have the sonic edge over a moly product. You could hoewver add about 3% of a moly additive to your graphite lubricant and get the best of both.
Now the power Up engineer told me that there product would have a lower coefficient of friction than moly or PTFE loaded lubricants. So you could also experiment with Power Up as an additive to your graphite lubricant to lower the friction while maintaining and improving the damping qualities of the graphite lubricant. Again about a 3% mix would do.
As far as graphite lubricants go I would say that the larger the molectural structure of the graphite particals the better the damping qualities. Graphite is a flaky structure by nature. With the addition of the Power Up additive there is no longer any need to keep the graphite particals small (so as to make them an effective lubricant) they can be made as large as possibel to enhance damping qualities. Do you know if the lubricant company who make your black oil provide specific data on the oil? Knowing the composition would make it easier to replicate (or improve on) while adding a superior lubricant at the same time.
I think the easiest way of making a custom task specific lubricant would be to find a top quality graphite based lubricant designed as a damping compound with the same viscosity as your black oil then add in the Power Up additive. Then you have the right weight of lubricant with maximum damping qualities with optumum lubricating qualities all in one bottle."

Also worth reading this.

Sure an apparently "cold" topic, BUT if and when you listen to a properly lubricated Garrard 301, you understand in a snap about the path.

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