Baldwin Designs, etc.

[Delwin D Fandrich]

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From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf Of
Erwinspiano@aol.com
Sent: August 23, 2005 10:38 AM
To: pianotech@ptg.org
Subject: Re: Baldwin Designs, etc.



   
  I have several comments about this. First when you say drive them back in,
I'll presume your not using a hammer?  right?  

Right. I use an air powered ratchet wrench.
 

 
   The other thought is if you 'all are using acu-just hitch pins then the type
of plate suspension system isn't all that critical as one can adjust the bearing
on the board without moving the plate, especially if the plate was installed in
a fairly reasonable elevation.   

This piano does not have vertical hitches. 
 
Yes, I am moving the plate to adjust downbearing. Specifically, the area
centered around the strut between the two treble sections.
 

 
    If one is not using acu-just then it seems to me  using a plate suspension
system has a greater potential for functionality in adjusting downbearing after
the plate is strung. However. Even if an adjustable system is used with
conventional hitch pins the lattitude  for lowering the plate has limitations. 

Yes, it does have limitations. Life, generally, has limitations. I doubt I could
make a change of, say, 5 mm. But I don't use this method to pick up more than
one or two millimeters. 
 

 
   The first being lowering the  plate  behind the bass bridge. A small downward
adjustment of the plate here can provide way more bearing than is wise.on
heavily tensioned bass strings, so the suspension system is limited here unless
bass string bearing felts .bars etc are readjusted to higher location. Possible,
but a bit annoying. 

 I don't recall ever doing this down around the bass section. But, let's
consider those "heavily tensioned" bass strings. What are we concerned with?
String tension, unison tension or section tension. I don't really care what the
tension is for a given string. I need to know the tension of the section. 
 

 
   Also an adjustment at the highest treble plate bolt location also has
limitations in any system, as I see it  , the stiffness of the plate flange
bolted to the block & the unwise application of to much rotational stress on
same if that highest bolt is forced more than a small amount. Too much here
induces a continual strain that may bite back in some form.ie. broken plate
,block pulled loose. But hey small amounts are often all that's needed. 

 You're quite right. Like most procedures we do in rebuilding a piano, this has
to be done with care and with a certain degree of thoughtfulness. A bit of
experience and an intuitive feel for what is going on in the piano as you effect
changes also helps. As I said above, I don't use this method to adjust anything
by more than a millimeter or two. 
 

 
  In my first encounter with using an adjustable Coleman plate suspension system
allowed me to apply much needed bearing on a piano that I had miscalculated
bearing load upon. That instance also required some shimming of duplexes etc to
get the desired tonal outcome in one section & dimish it it in another & I'm
happy to say in that instance it saved my behind & the gnashing of teeth of
course. The piano sounded grand? of course...... 

And this, of course, is the whole point: It saves wear and tear on the teeth.
 
Del

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