John I'm not sure I see the connection between doing a bit of load figuring, and the general principles of asking how load is distributed, where and in which direction(s). though I am sure most of us can go through the relevant source material and solve your little assignment below, I am also sure that like me, this will take those same of us a bit more time that perhaps you yourself or others already familiar in figuring these quantities will not use. That said... I'll get around to this, and other such tasks when I am able to find the time. And when I do I will no doubt have a greater understanding to be sure. The questions I ask however, are meant to clear up some moments of confusion so that I can more readily do exactly that, so if you feel it necessary to decline to answer these, then it will just take that much longer for me to arrive at that point. No problem though. Cheers RicB John Hartman wrote: > > Richard Brekne wrote: > > > One question about significant forces and unsignificant forces, that > > unsettles me a bit. It appears that we are writting off the significance > > of any particular stress if the resistance to that stress is very high. > > Take the straight tensioning of the rib for example.... that is looked > > away from because it has such a high tensil strength along the grain... > > yet the thing is stressed with the same psi that the panel is. So ok.. > > the panel readily compresses, and the rib does not so readilly > > lengthen... but the stress level still remains the same on both. I guess > > I am saying... so what if the rib only lengthens by a fraction of a > > mm... isnt it the amount of stress on it thats important ? > > Richard, > > I am not going to respond to any more questions on this topic from you > until you complete the assignment. > > "As an assignment why don't you figure out the force in psi that the > bridge pushed down on the panel? Get back to me with some numbers." > > Let's say you figure this for the first six note in the bass and the > last six notes in a Steinway B. Use typical bearing figures of say 1.5 > degrees. To get psi estimate the foot print of the brides. > > You mite as well figure out how much the panel compresses vertically > with this force as well. This can be found in Hoadle. > > I want to see all your work so scan you working notes and send them to > me in e-mail. > > 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 > > Piano Technicians Journal > Journal Illustrator/Contributing Editor [link redacted at request of site owner - Jul 25, 2015] > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives -- 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
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