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 ; Davehugh@msn.com=20
  Sent: January 22, 2002 8:49 AM
  Subject: Re: Baldwin Accu-Just Hitch Pins--General Information


  In a message dated 1/21/2002 10:35:32 PM Pacific Standard Time, =
pianobuilders@olynet.com writes:

     I think possibly you were confused about the order of subjects =
under discusion over the weekend. They did get convoluted and went from =
one thing to another. The Baldwin board specs were hashed out some and =
then it went on to the topic of setting crown in new boards, so you may =
not have picked up on the sequential discussions of this thread. That's =
why your post struck me the way it did. I didn't mean to necessarily =
relate those downbearing numbers to the baldwin system but to a fairly =
typical 60ft. crowned board with rib dimensions the same or similar to =
what ever the original heights were. This type of board is pretty common =
in shops across the country (as you know) and is probably where those =
asking the question will start at. Hence my reply. Perhaps my post was =
confusing.
        The prestressing method itself was what I wanted to make a point =
of and as you say the bearing values will change given a host of =
different factors. Although this method is old perhaps there other =
methods as well that I would certainly enjoy hearing discussed.
       I apologize for bristling a bit. The rest of you post was well =
taken and clear enough.

                                                          Best--Dale =
Erwin



But, Dale, I was aware that the thread had gone on, hence the new title =
on my post; Baldwin Accu-Just Hitch Pins--General Information.=20

The comment you bristled over was intended to address what I see as an =
problem in which the reader ends up applying downbearing numbers given =
by a respected rebuilder as gospel in situations in which they really =
don't apply. If you've not yet seen this happen, you will. Do you not =
vary these figures when confronted with a piano having a particularly =
long or short backscale? Are they the same for each make or brand of =
piano that you do? Are they the same for a Model S as they are for a =
Model D? Do you really set A-1 at 0 for both? Are the rib height and =
width always the same? What about a 6' 1" piano with 9 ribs vs. a 6' 1" =
piano with 11 ribs? Is your shop climate controlled? What if it weren't? =
What about the rebuilder in the south bellying a board in the summer? =
Without air-conditioning? Or in North Dakota. With heat!=20

As may be, life's not a constant and my post was intended to point out a =
few of the idiosyncrasies of the Baldwin Accu-Just hitch pin system and =
to remind the reader that not all pianos--in particular, Baldwin pianos =
using the Accu-Just hitch pin system--are constant either.

Regards,
Del





        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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