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<DIV><FONT face=Arial>Yes, if you are working with one particular =
design, then
one can come up with some repeatable, accurate downbearing scheme using =
dimes,
nickels and whatever else. In practice, as long as the backscale of a =
piano is
close to "normal" this method probably works OK. But as soon as you get =
that
oddball in with an unusually long backscale (or short) one could really =
start
changing things without realizing it.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Proper downbearing is very dependant on =
soundboard design.
Some boards need very little for optimal performance, while some are =
best set up
with quite a bit more downbearing.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Terry Farrell</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>
<A title=Crashvalve@aol.com
href="mailto:Crashvalve@aol.com">Crashvalve@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A =
title=pianotech@ptg.org
href="mailto:pianotech@ptg.org">pianotech@ptg.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, October 06, 2003 =
11:25
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Good at Machining =
WAS:
Reading a Board geometry</DIV>
<DIV><BR></DIV><FONT face=arial,helvetica><FONT face=Geneva =
color=#000000
size=2 FAMILY="SANSSERIF"><BR>In a message dated 10/6/03 8:47:52 =
AM, <A
href="mailto:mfarrel2@tampabay.rr.com">mfarrel2@tampabay.rr.com</A>
writes:<BR><BR><BR>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px =
solid; MARGIN-RIGHT: 0px"
cite="" TYPE="CITE"></FONT><FONT face=Geneva color=#000000 =
size=2
FAMILY="SANSSERIF"><BR></FONT><FONT face=Arial color=#000000 =
size=2
FAMILY="SANSSERIF">You want to measure the angular relationship of =
the
string in three areas: along the speaking length; along the bridge =
top; and
along the backscale just aft of the rear bridge pin. Those =
measurements will
give you all the data you need to characterize =
downbearing.</FONT><FONT
face=Geneva color=#000000 size=2
FAMILY="SANSSERIF"><BR><BR> <BR><BR></FONT><FONT face=Arial =
color=#000000 size=2 FAMILY="SANSSERIF">Be aware that all =
these references
to setting bearing to "the thickness of a nickel" or whatever level =
above
some reference point may be fine and dandy, but are completely =
dependent on
the length of the backscale. As the backscale length between two =
systems
where this type of measurement is being used varies, inaccuracies in =
the
reference thickness will be introduced.</FONT><FONT face=Geneva
color=#000000 size=2 =
FAMILY="SANSSERIF"><BR><BR> <BR><BR></FONT><FONT
face=Arial color=#000000 size=2 FAMILY="SANSSERIF">How much =
downbearing is
desirable will depend on the soundboard assembly design, where you =
are in
the scale, and a host of other factors I know very little =
about!</FONT><FONT
face=Geneva color=#000000 size=2
FAMILY="SANSSERIF"><BR><BR> <BR><BR></FONT><FONT face=Arial =
color=#000000 size=2 FAMILY="SANSSERIF">Terry =
Farrell</FONT><FONT
face=Geneva color=#000000 size=2
FAMILY="SANSSERIF"><BR><BR></BLOCKQUOTE></FONT><FONT face=Geneva =
color=#000000
size=2 FAMILY="SANSSERIF"><BR><BR>I really like that term =
backscale. If I
remember S&S threads a fiber line on the plate, shims it up with =
various
thickness metal slips, then sawcuts the cap to clear this line. This =
means the
bridge cap plane is so many thou above the string plane. This assumes =
bridge
cap is parallel to board and board is some kind of smooth curve and =
not
dimpled down. If you wanted to measure actual angles for the angular
relationship, you could but it ain't easy, and I also don't know =
factors are
involved in setting good down bearings, but I'd like to know =
!</FONT><FONT
face=Geneva color=#000000 size=2 FAMILY="SANSSERIF"></FONT>
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