On Mon, 31 Aug 1998, ari isaac wrote: [snipped "yada-yada"] > A sheet of hammer felt of graduated density - not merely graduated > durometer reading - is a good deal more expensive to have made. You can > see why hammer felt of uniform density throughout the scale tends to be > the norm. Graduated density means, among other things, that the wool > fibers have to decrease in diameter towards the treble end. This nice > feature of the felt sheet ensures not only a far more musical piano tone > but a huge increase in the voicing stability of the hammers. [playing Devil's Advocate] Actually, doesn't uniform density, top to bottom, give the technician a better shot at making changes in the density (using softeners and/or hardeners as necessary)? Graduated density might be equated with the proverbial moving target, right? How much gradation might one expect from top to bottom? Is it, indeed, gradual? I suspect that hammer felt that's supposedly uniform is actually not as uniform as one might wish. Makes things all the more interesting if there's an intentional graduation factor added to the mix! Something else...how does the manufacturer determine which wool fibers are of which diameter? Weighing each fiber? Weighing a pile of felt and figuring an average somehow? I'm amused by the thought that someone actually employs a worker who, using a magnifying glass, sorts felt fibers. "Let's see....this one's a .00035, this one's a .00020....HEY! Someone's messing with my sorted piles again!!" :-) Note: This was cross-posted to the CAUT list. Not being subscribed to the PIANOTECH list, I don't know where the discussion is/was going on the topic. Good reason to avoid cross-posting. Ron Torrella, RPT Piano Technician University of Michigan School of Music
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