evaluating sdbd. crown & bridge downbearings in a new piano

[Richard Brekne]

JIMRPT@AOL.COM wrote:

> In a message dated 9/20/1999 5:19:47 PM, richardb@c2i.net writes:
>
> << hmmm..  I'd be interested then in hearing about cracks in the soundboard
> that
> push upwards in a ridge shape. I have seen this on a number of occasions and
> assumed (and have had it explained to me) as being the result of pressure
> ridges building up due to excessive humidity.>>
>
>  Richard;
>  "Compression ridges" do not ordinarily have "cracks", although they may lead
> to "cracks" eventually. Thus if the board dries out significantly from when
> the compression ridges appear, and over a certain number of cycles of this
> ridging and flattening, then "cracks" 'might' appear at the location of the
> "compression ridge"(s).
> When a board has "compression ridge" 'cracks', when in the moisturized state,
> it generally is due to the fact that the ribs and board have seperated.
> Jim Bryant (FL)

Yep.. I have seen that and thats what I meant by compression cracks. I see this
rarely, but more then one occasion. Really marked compression ridges, a crack
along the ridge, with one side of the panel forced away from the ribbing
underneath. I have also seen them spread out after the piano has been moved to a
less humid location. Even tho the crack has spread, the ridges are still easily
identifiable.

Richard Brekne
I.C.P.T.G.   N.P.T.F.
Bergen, Norway