<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 6.00.2800.1141" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV> Ok guys and gals... I gots to eat crow here...  I think = anyways. As it turns out I managed to finnally solve the hammers bouncing all over = the place thing by turning up all the bed screws so that the key frame was = solidly bedded with the actuall wood of the balance rail a full 2 mm elevated = over the key bed.  <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p> So?  = That’s OK.  <o:p></o:p>  Huge increase in power, but this also caused an increase in keydip to 10.5 = mm (!)  <o:p></o:p> Well, Yamaha’s official spec. for grand key = dip is 10 mm, so 10.5 isn’t outrageous.  <o:p></o:p>  and forced a drop in blow to just above the cushions... perhaps the shanks are = about 2-3 mm off.  <o:p></o:p> That’s not way out of line, either  <o:p></o:p> However.... absolutly no bouncing of = neighboring hammers any more, and that feeling of loosing power is = gone.  <o:p></o:p> Great! What I dont get is why the = Balance Rail needs to be elevated so much. And how are we supposed to determine = the proper balance rail height to begin with ? I was always told that glide = bolts need to just make contact with the key bed... not to lift the whole darn = middle of the key frame up. Explainations please ? RicB -- Richard Brekne RPT, N.P.T.F. UiB, = Bergen, Norway <A href="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <A href="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A> <A href="http://www.hf.uib.no/grieg/personer/cv_RB.html">http://www.hf.uib.no/grieg/personer/cv_RB.html</A> <= BR>_______________________________________________ pianotech list info: <A = href="https://www.moypiano.com/resources/#archives">https://www.moypiano.com/resources/#archives</A>  <o:p></o:p> We’re not “determining proper balance rail = height”, we’re first, bedding the keyframe – and, yes, in some pianos the glide studs = barely touch, but the point is to eliminate any knocking of the balance rail = against the keybed when you tap on it.  = If the rail “floats” at all, then the keys don’t have a solid = fulcrum.  Depending on flatness of keybed, accuracy of = keyframe joinery, stiffness of the slats that connect the three keyframe rails, = and any distortion the tightening of the stack down onto the keyframe causes, = the balance rail will sit at different heights above the keybed in different = pianos.  Second, we’re setting an optimum key height, then leveling keys and setting = key dip.  This is done with = punchings and assumes the balance rail is already bedded.  I know you know this, = but....    = At the Little Red Schoolhouse (Yamaha’s technician seminar in = California), LaRoy Edwards likened the keyframe to a bridge:  with the keys (the load) out but the stack screwed on, the front = rail and back rail are bedded first (the two abutments at either end of the = bridge), then the balance rail studs are turned down to just contact the keybed  (strip of newspaper pulled = between stud and keybed has just a slight drag), then the keys are put back in.  There’s no spec. for = “height of balance rail”, just for key height, which is determined more by the keyslip = and the fallboard.             The height of the balance rail is determined by bedding the = keyframe and it ends up where it ends up.                  =     --David Nereson, RPT         </DIV></BODY></HTML>