Rib Support

[Richard Brekne]

John Hartman wrote:

> Richard,
>
> Have you actually tried this with real materials. If you had you would
> find that the cross grain panel will bend locally when you apply a force
> to it like down bearing. Also because the cross grain is compliant in
> relation to the cable it will absorb the force by compressing and
> collapsing. In any case very little of the force will be transmitted to
> the cable.
>

Of course I have tried it John, and of course the panel will bend locally. You
can actually punch a hole in the panel if the cable is long enough and the
ends are strong enough. I believe, if you had read my post carefully, that I
said that  << as long as the panel does not fail >> the entire system will
resist downbearing. Also... local bending or not, (unless the downforce
becomes very focused on one spot) there is still an outwards stress applied to
whatever is holding the panel bent... ribs, cable... what have you. This is
like impossible to avoid.


> What you have drawn here bears little resemblance to a soundboard. Once
> the ribs are glued on the panel and ribs work as one.
>

Again, if you had read carefully, you would see that my central point was
exactly that the panel and ribs work as a whole, or as one. My sequence of
drawings was just meant to illustrate part (and I believe one central part) of
why.


> John Hartman RPT
>
> John Hartman Pianos
[link redacted at request of site owner - Jul 25, 2015]
> Rebuilding Steinway and Mason & Hamlin
> Grand Pianos Since 1979
>



--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html