Let-off in piano

[Keith Roberts]

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I think the comment I heard was "get it as close as you can on the =
bench". There is always a good flat surface you just need a thick =
blanket so you don't scratch the lid. When you adjust everything to =
samples, the key bed can just lay flat because when you put the action =
back in the piano everything adjusts back into place with the samples. =
Then because string height can vary note to note, fine adjustments must =
still be made in the piano. Try taking a gauge a mm longer and then the =
hammer should bobble slightly when you drag it down the string. That is =
easy to see the low ones.

I take my folding keyboard stand to use as an action table.

kpiano


----- Original Message -----=20
  From: jason kanter=20
  To: Pianotech=20
  Sent: Tuesday, February 01, 2005 10:00 AM
  Subject: Let-off in piano


  Just reading David Nereson's post about the old Bl=FCthner 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."

  | |   | | |   | |   | | |   | |   | | |   | |   | | |   | |   | | |   =
| |   | | |   | | =20
  Jason Kanter . piano tuning regulation repair
  jkanter@rollingball.com . cell 425 830 1561
  serving the eastside and the san juans

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