--On Friday, October 3, 2003 7:56 AM -0700 Don Mannino <dmannino@kawaius.com> wrote: > Hey Fred (and list), > > I sort of figured you were putting more friction there in compensation > for conditions. They should not loosen up as much as you said, though - > an average of .5 gram resistance drop in hammer flanges after 20,000 > keystrokes is what I found when testing the process. >snip< I got to thinking about number of strokes per key in a practice room piano, wondering if there was any way to come up with a reasonably accurate guesstimate short of using a Disklavier or equivalent to count. After some thought, it occured to me that scales were a countable quantity. Any piano major must be able to play scales in all keys, four octaves, hands together at the octave, at a minimum of 144 mm to the quarter note in sixteenths (metronome set at 144, four notes per beat). Scale practice is a fair portion of what goes on in practice rooms. This becomes a simple calculation: two keystrokes per note (both hands playing simultaneously), four notes per beat, 144 beats per minute, 60 minutes per hour, equals 69120 keystrokes per hour. Divide that by 88 keys, and you come up with a rather incredible 785 keystrokes per key per hour. (Boggled my mind when I calculated it. My seat of the pants estimate was 50 - 100). Looking at how scales are actually played, a typical run through all the keys (as in major and minor) will use notes between F1 and F7, or only 73 keys. And the outer keys, being played by only one of the hands, will get less strokes. So the number of keystrokes in the middle 4 to 5 octaves will be considerably higher - maybe 1000 per hour. Now one might ask the question whether scale practice is typical in production of keystrokes. Obviously there are lots of practice hours devoted to slow movements, to hands separate, etc. On the other hand, there are activities that produce considerably more keystrokes per minute: trills, tremellos, glissandi (keyhbushing destroyers), double octave passage work, heavy textured playing (3 to 5 keys played by each hand at once). So if scales produce somewhat greater than average keystrokes, I don't believe the number is outlandishly high in comparison with normal practice room use (talking about piano major practice rooms, with energetic virtuoso wannabes). Taking a conservative figure of 200 keystrokes per key per hour (conservative compared with scale use), and extrapolating for an annual figure, we can multiply by 10 hours per day (low for some institutions), 30 days a month, 10 months a year (allowing for down time in summer), and come up with 600,000 keystrokes per key per year. So it wouldn't be stretching it too far to say the the middle keys on a heavy use practice piano might receive one or two million keystrokes per year, maybe even more. All very theoretical, but I think it probably comes reasonably close to reflecting reality. Does make you realize how important it is to do meticulous travelling and squaring of heads on shanks, and to keep those screws tight. And explains those broken strings and worn out actions. And the crazy high workload recommendation in the Guidelines. Regards, Fred Sturm University of New Mexico
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