Let-off in piano

[jason kanter]

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Just reading David Nereson's post about the old Blüthner he takes care of.
He comments: "Can't regulate let-off in the piano -- no way to get at the
regulating screws."

Which brings up an important point for me. How DO you regulate hammer height
and letoff in the grand piano? The method I learned is: Pull the action,
measure string height at the extremes of each section using a string height
gauge and a busines card; put the action on a nice, firm, flat surface (I
know that this is the place where errors creep in, if the keybed and the
work surface are not both quite flat); use a contraption to simulate string
height; and regulate hammer height, letoff, checking, drop, etc outside the
piano.

In some situations I have had to do an on-site regulation where there is no
good, flat surface for the action, so I've tried to do it in the piano. I
can't see how you can do a good job with it. Feeding a hammer blow gauge
through the dampers, turning it 90 degrees and pulling it gently up to
contact the undersurface of the string, and holding it there while trying to
get an eyeball on the hammer surface from the front of the piano and using
the other hand to regulate the capstan ... difficult enough to do samples
but what a challenge to do them all that way. Very hard to get a good line
of sight over the hammer flange under the pinblock. So I have resorted to
approximating, measuring only a few, pulling the action into my lap and
eyeballing the tweeners. I *know* the results are not as good as what I
could do on a good bench.

Same issue for letoff, and same for backcheck. No doubt you more experienced
folks have developed fast, efficient, easy ways to do this. Please
enlighten.

Does Bill Spurlock's description sound like what any of you do? "hunching
over the stretcher, peering past the dampers and through the strings to
judge let-off distance, then looking under the pinblock to place the tool on
the adjusting screw, then leaning forward again to watch as you make the
adjustment. All the while you must "squeeze" the key gradually to slow
hammer movement enough that you can accurately see the let-off point."

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Jason Kanter . piano tuning regulation repair
jkanter@rollingball.com . cell 425 830 1561
serving the eastside and the san juans

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