David Skolnik wrote: > Also, it does allow the > possibility of a false zero reading. O.K. I see. If my tool shows zero bearing there could still be bearing due to some weird tilt to the bridge. I am not too worried about it, it would take a lot of tilt to be a significant amount of bearing. > To say, in your semi-mocking manner > that "you guess somewhere there are pianos with serous bridge roll" > seems either uninformed or disingenuous. I never use a semi-mocking tone only the full version. When I am mocking you will know it. I was just pointing out the limits of my experience. I work almost exclusively on old Steinway and M&H grands. While I have seen examples of minor rolled bridges and occasional areas with negative bearing, like the top end of bass bridges, for the most part I could not blame the pore tone I was hearing on these factors. It seams to me that more general factors like a lack of crown and loss of down bearing were the main factors. Other things like old rusty strings, loose bridge pins, worn hammers poor voicing and a million other things are all more likely cause of poor tone. > Are you basically saying that the issues, such as negative front or net > bearing, which are illuminated by this tool, are unimportant to you > because you are rebuilding anyway, or because you disagree that they > adversely impact the piano's performance, other things being correct? As I said, it is the total bearing I am interested in, variations in front or back bearing within the small tolerances I see on the pianos I work on are not going to result in any tonal characteristics I can hear so I just ignore these. As I also said my experience is limited so somewhere there probably are pianos made either by design or mistake with horribly misshapen bridges that cause tonal problem all on their own. Thankfully I don't have to work on these. Though I don't see it very often bridges can roll forward due to unequal string tension. If you pull up the strings on a piano that has not been tuned for a long time and is considerable flat you run the risk of pulling the bridge forward. If the strings are rusty they can't equalize in tension over the bridge. A lot of force is then pulling the top of bridge and it can and does roll the bridge forward distorting the soundboard. 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] John Hartman The Universal, How-to, Hands-on Illustrator [link redacted at request of site owner - Jul 25, 2015]
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