<html> <body> At 02:13 PM 6/3/2004 -0500, RonN wrote: <blockquote type=cite class=cite cite><blockquote type=cite class=cite cite>The "angle" of deflection is a hypothetical construct.  If the profile of the bridge surface was the peak of a triangle, you could speak of an "angle" of deflection, however, distortions in the bridge surface (curvature or string held to bridge contact by pins) can alter the angular perception of deflection.</blockquote> Not really. That's the whole purpose of using a bubble gage instead of a dial or rocker type gage. With the bubble gage, overall bearing is overall bearing, regardless of what the bridge top looks like. Overall bearing is what you're interested in when you want to know how much load the strings are putting straight down on the soundboard. Overall bearing is what you are comparing against remaining soundboard crown. Front and back bearing relative to the bridge top are termination concerns.</blockquote> The dreaded BLUE Ron - Maybe I should engage the lawyer I suggested for Joe Goss.  You're correct, I think, about the angle.  I have continued, out of habit, to mix my concerns about termination with those of soundboard loading.  However, there are still some components of your comments that I would like to respond to, in turn. As I understood it, listening to Tom Lowell describe the proverbial drawing on the napkin, the purpose of the gauge was as much to be able to isolate the front and rear components constituting net bearing.  Maybe I misunderstood.  Whether or not it makes a difference whether we achieve a given net bearing with a front and rear positive or with a mixture of positive and negative, is a sub-question of soundboard loading, apart from the issues relating to termination.  This, apropos your statement above  "... (the) load the strings are putting straight down on the soundboard".  Do you have any thoughts regarding possible acoustic differences (effect on SB impedance) between a (basically) neutral load (positive front and rear bearing) and one which introduces distortive potential ( positive / negative)?  This would be another reason for measuring the individual components. <blockquote type=cite class=cite cite><blockquote type=cite class=cite cite>Still, the challenge of accurately measuring and conveying  the nature of a particular piano's string deflection, including the bridge, is, to me, a separate question from how much or little there should be or how it does or doesn't affect the instrument's qualities.</blockquote> You'll never get an absolute answer to that one. </blockquote> This wasn't meant as a question. <blockquote type=cite class=cite cite>Get five techs to evaluate a piano with a flat soundboard and zero-to-negative overall bearing at some point in the scale.. One will say the piano sounds terrible, and indicate the bearing and crown as likely causes. One will say the piano needs new hammers and voicing, and that the crown and bearing aren't indicative of anything at all. One will say that this is the most beautiful sounding piano he's ever heard, and you shouldn't change a thing. One will say the action needs bedding. One will say the piano is perfect without even lifting the lid or playing a key, just from the name on the fallboard.</blockquote> I wasn't speaking of evaluating the piano, or, for that matter, the bearing.  I'm talking about being able to take consistant, repeatable, duplicatable measurements, which can be accurately communicated, and which could be correlated with any other method of measurement which purported to accurately measure the same components.  In other words, I should be able to relate the net downbearing I measure with a bubble gauge with what I would get using a Hartman stick. As for the casters, that can only be determined with a marble, placed carefully on the... David Skolnik </body> </html>