JICO rates stylus wear

the thin end of the wedge
dlaloum
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Post by dlaloum » 01 Aug 2011 06:27

Is that proportional to the index finger? :twisted:

TA

Post by TA » 02 Aug 2011 22:26

LD, did you make any calculations on wear? (I do not remember, but it should be possible to make a simulation of wear given the surface areas and the materials in play)

Audie
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Post by Audie » 03 Aug 2011 05:55

Interesting this topic on stylus wear. A lot depends on stylus type, the arm, accuracy of setup-VTF,VTA, bias, azimuth and record condition.
ZYX claim some of their cartridge styli have a life of 2000 hours under ideal conditions. Van den Hul also claim long life.
I VPI clean my records and also treat them with last preservative, and sparingly treat my stylus with Last stylus treatment, which together I would expect to preserve the stylus, as well as the record.

I have just purchased a ZYX R1000 Airy-3 S SB cartridge and will be cautious, and expect only 1000 hours use before having it microscopically inspected ( if I'm still around then :?: )

Audie.

Guest

Post by Guest » 03 Aug 2011 11:48

wrote:LD, did you make any calculations on wear? (I do not remember, but it should be possible to make a simulation of wear given the surface areas and the materials in play)
Hi Thomas_A. No, I've not even tried numeric wear rate calculations.

But some principles seem to challenge conventional views on flat spot development. Even in very simple models, where errosion rate is simply a constant volume of stylus removed per unit time, there are interesting general predictions.

For example, the rate at which 'flat spot' depth and radius develops should slow down significantly as time goes on. Flat spot depth and radius development would slow down with the square of time. In other words, if wear means 'bigger' or 'deeper' flat spots, wear rate would progressively (and significantly) slow down as time goes on.

Other factors might even exaggerate progressively slower wear rate. For example, if wear rate reduces with reducing pressure [area of the wear spot increases so same VTF infers less pressure].

In this conventional flat spot model, wear rate should significantly slow down as time goes on. That conclusion can't be avoided, i think.

If imperical observation is that wear based deterioration does not slow down, then reducto ad absurdum says the flat spot model can't be true. Doesn't it !?

TA

Post by TA » 04 Aug 2011 16:36

One way to find out if wear exist would be to measure the friction by the stop method. Compare two stylii, eg OM10, new and used. It may however also be a function of ageing suspension.

TA

Post by TA » 04 Aug 2011 16:51

Regarding "flat spot" wear - is that even geometrically possible given the variable curvature of the grooves? Also, Given the offset angle this wear should be asymmetric, unless a linear tracking arm is used.

dlaloum
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Post by dlaloum » 04 Aug 2011 17:11

The styli that I have seen under the microscope which appear to display "wear" patches (assuming I am looking at the right thing) - have all looked asymetric.

Guest

Post by Guest » 04 Aug 2011 19:10

wrote:Regarding "flat spot" wear - is that even geometrically possible given the variable curvature of the grooves? Also, Given the offset angle this wear should be asymmetric, unless a linear tracking arm is used.
I agree, 'flat' seems impossible.

Yes, wear should be somewhat asymmetric. But if 'spot size growth ' slows down with square of elapsed wear time, that would reduce observable difference, of course.

DL, from the photos I don't believe your method has necessary resolution to observe contact locations for wear. Asymmetry you observe could be anything, including lighting. Personally, my own efforts don't reveal anything conclusive, as might be expected if there weren't anything to see.

Thomas_A, stop-time friction would be an interesting measurement to chart versus time/wear. I have clocked up a few hundred hours on a stylus since last measurement. Will re-measure !

TA

Post by TA » 04 Aug 2011 20:50

dlaloum wrote:The styli that I have seen under the microscope which appear to display "wear" patches (assuming I am looking at the right thing) - have all looked asymetric.
What I would believe is happening is that the inclination angle of the stylus tip changes over time. It will be "polished" to the angle of the groove walls. But spots could never be flat, unless you e.g. forget the stylus in the run-out groove for a couple of weeks (since the groove is unmodulated). A simple conical stylus will be polished to an elliptical shape at the tip (90° to the ordinary elliptical stylus). This would perhaps be visible using a high-power microscope.

(And if I remember correctly from an older Linn manual, the tip could be visualized front to back to see whether there is a change in inclination angle. There was no mention of flat surfaces. I do not remember what the Shure documentation showed/claimed as signs of wear - flat spots or inclination angle?)

I wonder if these so-called wear figures/pictures of flat areas derive from running the stylus in a locked silent groove, like a lead-lout groove?

Guest

Post by Guest » 04 Aug 2011 22:18

dlaloum wrote:The styli that I have seen under the microscope which appear to display "wear" patches (assuming I am looking at the right thing) - have all looked asymetric.
Labels on the photos you posted earlier in the thread suggest any asymmetry is opposite from what one would expect to find, DL. I doubt you're looking at what you think.

desktop
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Post by desktop » 12 Aug 2011 03:36

Sorry I have not kept up with Vinyl Engine recently but I have 400 pounds of red plums to process and with the season over, it is a 20Hr/day job.

I thought I'd mention that while Thomas_A may be right that a conical stylus polishes itself in the groove to an elliptical (or even line contact shape) that shape is 90 degrees out of alignment with the groove. When CBS did its testing to determine vinyl record groove and stylus wear in the 50s and 60s they hoped there could be a way to turn the styli 0 degrees to realign the usable position of the styli tip but I don't know if their research came to anything.

From my perspective, living and using stereos in the 60s, the "cap off" grind top on the tip would cause problems as deep grooves could "bottom out" this newly ground tip configuration. I'm sort of glad that nothing came (product-wise) of this CBS research because the period of time when the groove tip was a .2 mil surface (after being ground down) it was cutting and smashing the grooves to pieces.

I'll be back next month after we decide what to do with 40 bushels of pears and apples coming next. Blackberries & mulberries were terrible, but plums were incredible. Cherries and grapes could be good but are unpredictable. Natural super-fresh food rates above audio for me, though not by much.

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