Down-Bearing for Old Board

[Erwinpiano]

Terry
    I,m sure there are many differing veiws on the subject you raised but
the answer will probably contain similar threads.  A very fine 4 part sereis
of articles printed in the P. T. J. around august ,sept.of 1995 By John
Hartman has been an enormous help in applying downbearing principles to me
and others. I beleive the series was called downbearing and the affects on
tone.  This article includes some guidelines for setting up old boards as
well.
       My advice is od not apply more bearing than is needed to compress the
board to a flattened  position after it is strung and up to pitch.  The fact
that you're in florida means that the moisture content in your board is
probably high or could be . I think saftey dictates dampchasers be run  with
humistat for for many  days before making the final determination on how
much crown was actually acheived(have never had much luck reintroducing
crown through shimming and I've tried).
     How much crown is there really ? This should be meas. after drying to
45% r.h. to get a real figure.  If a newfully crowned   board exhibits 1/4"
to 3/8" in the unstrtung condition at 45% how does that compare to what your
seeing?  Usually what is typically described to me by others as" alot  of
bearing" is a board in fairly flattened or flat condition.   I.E. it has two
m.m. of crown.  Then you can see thats not much but if thats all you have
then by all means try to use it to your advantage but do not put more than
two or three m.m. bearing on the board or something safe.  Remember
compressing the board changes this light weight structures impedance (which
is a good thing) and makes it a more effeicent sound producing device.
(moving more air / sound waves)
 Just food for thought and hope it helps
Dale Erwin