[CAUT] killer half-octave

[Donald McKechnie]

Ron O.

This particular D (1946, CD in New York for 20+ years before coming  
to IC) would be a great experiment for a modification along your  
lines of thinking. Getting the money and finding a person willing and  
able will be another thing entirely. I can only hope!

Thanks,

Don

> Hello Don and all,
>
> 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.
>
> Take a look at the following image of a Hamburg model D from the  
> 60's, in the process of being rebuilt.
>
> http://overspianos.com.au/stdctoff1.jpg
>
> 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.
>
> 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.
>
> 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.
>
> http://overspianos.com.au/stdctoff2.jpg
>
> Here's an image of our 225 grand piano's belly rail in the treble  
> area.
>
> http://members.optusnet.com.au/ronovers/oversno6.2.jpg
>
> 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.
>
> Ron O.


Don McKechnie
Piano Technician
Ithaca College
dmckech at ithaca.edu
607-274-3908




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