Downbearing - Setting with a loose board

[Overs Pianos]

Hello David,

>. . . Do you think that the results obtained using the pre-load 
>method are (or can be)  equivalent to the method you describe?

The primary reservation I have about pre-loading the board with 
wedges under the plate struts is that it is difficult to know just 
how much pre-load is being applied. The scale tension and downbearing 
forces, for a chosen strung-downbearing angle, can be calculated. If 
the board were to be loaded with a distributed system of weights to 
simulate the chosen-downbearing force on the strung piano, this would 
be a very accurate way of determining an appropriate level of 
unstrung downbearing. The problem with pre-loading in this way would 
be the requirement of having 300 - 500 Kg of suitable weights on hand.

>Is there a significant advantage to your method?   Is there a way 
>you factor in differences in panel flexibility?

As Ron N mentioned in his post, when dealing with an original sound 
board, pre-loading is very important to gain a insight into the 
deflection under load of the unknown sound board. When dealing with a 
new board, the resistance of the board should be a known quantity.

>What are stringing pillows?

The small blocks on the hitch plate immediately in front of the hitch 
pins (which are sometimes individual blocks or cast in groups). Not 
all manufacturers use them, but if the bridge heights are determined 
and the notching completed prior to gluing the board into the case, 
the blocks can be adjusted to fine tune the downbearing prior to 
stringing. Fazioli builds his pianos using this method as do we at 
present. We manufacture various block heights (from 4 to 7 mm in 0.5 
mm increments) and choose the appropriate block for fine adjustment 
of the downbearing.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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