Let-off in piano

[Dean May]

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Jason,

After  practice you can get pretty good at using the blow distance gage to
set the end hammers. Any helper will make the job easier, holding the gage
for you while you peer over the hammer flanges and turn the capstans. I
usually set the remaining hammers in the piano. With experience, you get
used to it. If there is not enough room to see, I'll pull it out and set it
on the workbench/piano lid/whatever is handy and level. Again, with
experience you get pretty good at setting a level line.

After watching the Kawai Master Tech prep a Shigeru, I now eyeball the
letoff on the end of section hammers. He set it at 1 mm. I go a little wider
usually. Then I made a tool similar to Spurlock's
(http://www.spurlocktools.com/id24.htm). But I'd recommend you buy his
($33), I'll probably end up buying one myself. It is really slick. It allows
very uniform settings on letoff and drop. After I set all the letoff in one
section, I hold the key down, bring the drop screw up until the shank comes
off the jig, then turn the screw back down just a little past where the
shank comes back down to touch. This makes drop right at letoff which really
makes it feel nice.

Dean
  -----Original Message-----
  From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On
Behalf Of jason kanter
  Sent: Tuesday, February 01, 2005 1:00 PM
  To: Pianotech
  Subject: Let-off in piano


  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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