Baldwin Accu-Just Hitch Pins--General Information

[Delwin D Fandrich]

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  ----- Original Message -----=20
  From: Erwinspiano@AOL.COM=20
  To: pianotech@ptg.org=20
  Sent: January 21, 2002 1:08 PM
  Subject: Re: Baldwin Accu-Just Hitch Pins--General Information


  In a message dated 1/21/2002 10:40:39 AM Pacific Standard Time, =
pianobuilders@olynet.com writes:



    Subj:Baldwin Accu-Just Hitch Pins--General Information=20
    Date:1/21/2002 10:40:39 AM Pacific Standard Time
    From:pianobuilders@olynet.com
    Reply-to:pianotech@ptg.org
    To:pianotech@ptg.org
    Sent from the Internet=20



    Dale, Carl, et al,
    .

    Mostly, how much loading any specific soundboard must have is a =
function of how massive and how stiff the soundboard assembly is. This =
is not a universal constant. Dale=E2=80=99s string deflection numbers =
would not work[at] all for one of our boards. As to whether they would =
work for one of Baldwin=E2=80=99s current boards=E2=80=94I cant say. =
With the Accu-Just system Baldwin has used a fairly light crown =
radius=E2=80=94



    Del--Just so it doesn't appear that you're dismissing my downbearing =
deflection no. derived from the experience myself and others out of =
hand, let me Re-state that these no.s are real do work well in =
NON--REDESIGNED soundboards, which I must point out most of us are =
doing. I think I was fairly specific as to the type of replacement board =
application that these numbers do commonly work in.=20
No, I'm not dismissing them at all. And I'm certainly not dismissing =
your experience. I thought I was being pretty specific when I said your =
downbearing numbers wouldn't work for our soundboards. And they may not =
work for Baldwin boards--which is what the original discussion was about =
if I recall correctly. Anyway, my apology if I wasn't specific =
enough--I'm just trying to point out that these numbers are specific to =
the type and design of the boards you put in. They may or may not work =
well for the boards someone else puts in using some (perhaps only =
slightly) different procedure. Or some different combination of =
materials.=20

There are lots of variables that go into setting up a soundboard system, =
including determining the amount of string loading on the soundboard. =
The numbers you and others are quoting are numbers that work well for =
you. You've done a lot of boards and you're comfortable with them. But =
they are not universal numbers for all soundboards and for all pianos =
though they typically get used that way. When the question is asked, =
"How much downbearing should there be on a new soundboard?" I'm not sure =
we can answer without either asking or giving a bit more information, as =
you're doing below:



    These values of downbearing  work well for me on 60ft. rib crowned =
boards(treble radius are tighter) but with some modification of the =
system of prestressing, I suggest the procedure could be applied to many =
if not most soundboard systems that exhibit some stiffness as they're =
being test loaded. Obviously totally flacid or under crowned systems =
woulf require a different approach.
    Perhaps you'd like to share what values you consider workable in a =
non-redesigned rib crowned soundboard system ? Or in your design system =
for that matter.
I do so in classes I give on the subject. But without being able to =
illustrate and discuss the design of the soundboard the numbers wouldn't =
mean much. Let's just say that they have somewhat more flex in them than =
you're probably used to and they have somewhat more crown, hence the =
downbearing settings are quite a bit higher than you would use.

Del



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