<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: [CAUT] killer half-octave</title></head><body> <div>Hello Don and all,</div> <div><br></div> <div>I have a clue as to ". . . why this happened". After considering the structure of these belly rails, I would be very concerned about connecting such a tension device. In my workshop, the solution to this soundboard-perimeter-support-stiffness problem has been to ditch the 'bell' and fit an extra back beam in the treble.</div> <div><br></div> <div>Take a look at the following image of a Hamburg model D from the 60's, in the process of being rebuilt.</div> <div><br></div> <div><font face="Lucida Grande" size="-4" color="#000000">http://overspianos.com.au/stdctoff1.jpg</font></div> <div><br></div> <div>Notice the belly rail where the back beam connects with the belly rail. Now look at the members which are glued together to make up this belly rail assembly. The total thickness of the full-depth-section of this belly rail is a mere 30 mm wide. The pine piece immediately behind the belly rail, with the large knot in it, is the filler piece between the belly rail and the laminated piece which actually connects with the soundboard. It amazes me why a manufacturer, who goes to the trouble of building a rim with a solid 85 mm overall thickness, would fit only a 30 mm thick belly rail to a concert size instrument. It is totally under-engineered. The addition of an extra back beam, coupled with the bent bass corner cut-off really helps to stiffen these cases to appropriate levels across the belly rail in the treble area. The dimensional size of this belly rail also goes some way towards explaining why this manufacturer chooses to glue the keybed to the belly rail.</div> <div><br></div> <div>Another practice which I find baffling is why some manufacturers choose to use weak-and-lossy pine for the connecting strip between the belly rail and the soundboard perimeter support strip across the belly rail. Quite a few manufacturers do this. It would seem to be a wonderful way to cripple the structural integrity of the soundboard's perimeter support.</div> <div><br></div> <div>Here's a second image which shows the extra back beam and the bass side cut-off, when viewed from the font of the piano.</div> <div><br></div> <div><font face="Lucida Grande" size="-4" color="#000000">http://overspianos.com.au/stdctoff2.jpg</font></div> <div><br></div> <div>Here's an image of our 225 grand piano's belly rail in the treble area.</div> <div><br></div> <div><font face="Lucida Grande" size="-4" color="#000000">http://members.optusnet.com.au/ronovers/oversno6.2.jpg</font ></div> <div><br></div> <div>The full depth members of this belly rail assembly is made from two pieces of rock maple which are each 30 mm thick, making a total belly rail thickness of 60 mm. The piece which connects the full depth section of the belly rail to the soundboard-perimeter-support piece is also made from rock maple. The back beams are also made from rock maple, and there are two of them covering the treble sections. The treble is where we need stiffness and structural integrity, not at the bass/treble cross where the plate horn collects. The 'tone-collector' myth is somewhat ironic, since the practice of running most of the back beams to the cross between the bass and treble makes this area stronger at the expense of the treble sections, which are the ones which really need it. If design people would pay more attention to structural requirements instead of pandering to piano-making myth and folklore, we might get to take contemporary piano design somewhere worthwhile while we're above ground. Please note that these comments are general in application, and not intended to be directed at a single manufacturer.</div> <div><br></div> <div>Ron O.</div> <div><br></div> <div>At 10:18 AM -0400 17/5/07, Donald McKechnie wrote:</div> <blockquote type="cite" cite><br></blockquote> <blockquote type="cite" cite>Be very careful with the tension resonator. The attached picture tells why. I followed the instructions to the letter but the belly rail was not up to it for some reason. I spoke to Bob Grijalva about the problem and he said it was a first. No clue as to why this happened. The funny thing is it appears to have had no effect for the worse or better. I just left it in and has been there for about a year. This piano is due a new soundboard so the belly rail can be repaired then.</blockquote> <blockquote type="cite" cite><br></blockquote> <blockquote type="cite" cite>Don</blockquote> <blockquote type="cite" cite><img src="cid:a06240808c2726955f9d9@[10.1.1.4].1.0"></blockquote> <blockquote type="cite" cite><font size="-1">Don McKechnie</font></blockquote> <blockquote type="cite" cite><font size="-1">Piano Technician</font></blockquote> <blockquote type="cite" cite><font size="-1">Ithaca College</font></blockquote> <blockquote type="cite" cite><font size="-1">dmckech@ithaca.edu</font></blockquote> <blockquote type="cite" cite><font size="-1">607-274-3908</font></blockquote> <div><br></div> <div><br></div> <x-sigsep><pre>-- </pre></x-sigsep> <div><font face="Times New Roman" size="+1" color="#0000FF"><b>OVERS PIANOS - SYDNEY</b></font></div> <div><font color="#000000"><i>   </i></font><font color="#0000FF"><i>Grand Piano Manufacturers</i></font><font color="#000000"><br> _______________________</font></div> <div><font size="-2" color="#000000"><br> </font><font color="#000000">Web http://overspianos.com.au</font></div> <div><font color="#000000">mailto:ron@overspianos.com.au<br> _______________________</font></div> </body> </html>