Richard Brekne wrote: > > I am under the impresseion that the 0.8 % compression rate is really > just what is the compression level at the interface with the rib, and > that as you move towards the top side of the panel this is significantly > less... tho I dont see yet how to figure this damage. This would seem to > lower the overall damage threshold further.... tho I am not sure yet as > to how much. Yes I think you'r right but it couldn't be very much. > Still trying to figure where Ron got 580 psi as perpendicular to grain > FSPL for Sitka when it says 710 psi in the table on page 79 of Hoadly's > book. Thats about a 20 percent increase strengthwise. I looked and you'r right. The 580 comes from "Wood as an Engineering Material". Hoadly's is more resent, in the revised addition, so maybe it reflects the new standard. Some of the other figures have been changed as well. Check his book for an explanation, I recall there was something about this in his book. 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]
This PTG archive page provided courtesy of Moy Piano Service, LLC