<html> <body> David L - I didn't see your post before I sent mine.   Here are my problems, which may already be familiar to you from the pianotech forum: At 08:20 AM 4/1/2004 -0800, you wrote: <blockquote type=cite class=cite cite>I think the question that first needs to be asked is why do you need to tap the strings.</blockquote> We seem to be asking the same question, but we're not.  You're asking "why the STRINGS?".  I'm asking "why does the string need to  contact  the front edge of the bridge?"  What degree of departure from perfect create what perceptible, observable effects? <blockquote type=cite class=cite cite> The assumption is that the strings ride up on the bridge pins.  Assuming positive bearing and proper bridge pin angles with a bridge and pins in pristine condition that is not likely. </blockquote> Most of these discussions make these assumptions, or that any evident negative front bearing is due to overly aggressive tapping.  In my experience, these are not self evident. Negative front bearing can exist (with positive net) from relatively early in the life of a piano, due to errors in manufacture, bridge roll, or other conditions inducing severe compression. <blockquote type=cite class=cite cite> The reason tapping down seems to make a difference, however, is important to examine.   Over time, the strings cut into the bridge pins creating a small indentation or notch in the side of the pin that the string tends to want to ride in.  </blockquote> I'm OK with this conception. <blockquote type=cite class=cite cite>At the same time, compression on the bridge top (exacerbated by tapping down on the strings) lowers the contact point on the bridge.  </blockquote> Assuming enough downbearing ( at some point in time) to compress the wood fibers, I would place more responsibility on the seasonally induced increase in downbearing more than the unsubstantiated certainty of aggressive tapping.  And, of course, there is the speculation that the bridge surface itself rides up the pin in humid conditions, in turn, pushing the string further up the pin. The question there would be whether the string then follows the board back down in the dry season. <blockquote type=cite class=cite cite>Unseating on the bridge top tends to occur when the contact point on the bridge top is lower than the indentation in the side of the pin.  Therefore, you are much better off tapping down the bridge pin than the string. </blockquote> But this assumes either that the pin is not already bottomed in the hole or that you can safely drive the pin into the bridge body, like a nail. <blockquote type=cite class=cite cite> Tapping down the string will, at best, be a! temporary measure. </blockquote> I agree. <blockquote type=cite class=cite cite> At worst, it can create a further disconnect as the contact point on the bridge top is lowered due to further compression of the bridge top.</blockquote> Here it is again.  What do you imagine (I don't know the answer) the differential between the force needed to seat the string and that required to further indent an already compressed piece of rock maple?  I find the Compression by Tapping argument suspect. <blockquote type=cite class=cite cite> Furthermore, false beats are usually a product of loose bridge pins and a flagpolling of the pin which creates an oscillation.</blockquote> The false beats created by loose bridge pins is different from the distortion caused by faulty termination. Of course, neither of us has definitive documented proof of our positions.  I, at least, do not.  While this discussion might seem too abstract to warrant this amount of time and space on this list, it disturbs me to think that the information we disseminate might not be as solid as we would like to believe.  Of course, the other disturbing thought is that I might be totally wrong and that my subscribing privileges haven't yet been revoked! David Skolnik </body> </html>