V T wrote: > Hello John, > > I fully agree with you regarding the "grams" statements. Perhaps the best > we can do using this measure alone is to make the friction uniform, or well > graduated from end to end. I agree too, but where's the alternative measurement process that produces a measurement in the proper terms? > However, swings may actually be a useful and very efficient method of > measurement. I am thinking that the heavier hammers can perhaps benefit > from slightly higher friction than the light ones. Heavy hammers need > better (tighter) bearings to maintain good alignment under heavy loads, and > the higher friction (within normal limits) also imparts some control to the > player when the inertia of the lower hammers becomes noticeable. While > swings don't translate into MKS units of measure, they can in their own way > act as a unit that makes sense to piano technicians. Yet again, it's not absolute measurements that are needed in practical application, it's a reliable means of comparison within a limited range, compared to a nominal local "standard" that defines a point of departure for the individual tech. We're grading on a normalized curve. My "standard" is a clip clothes pin, and I swing grade sets before installation. I put the tight centers in the treble, because that's the area that needs firm centers for tone production. The looser centers go in the bass, because that's where the hammer weight problems are, and I don't want any more center produced friction than necessary. And you know what? In the end, with well balanced and regulated actions, I doubt anyone could detect by which method the shanks were sorted. > Ideally, I think we would probaby like to know how compliant the bearing is > to the twisting of the shank and also how much torque it takes to turn the > shank around the flange. But for know, I am reasonably happy with the swing > test for simultaneous measurement of these two parameters. > > Vladan Likewise. Ron N
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