Bridge Doglegs, was: Spreadsheet info / Jason Kanter

[Delwin D Fandrich]

If memory serves, the notion that the bridge should not be "doglegged" comes
from the philosophy holding that sound needs to travel unimpeded back and forth
throughout the interior of the bridge. For more on this see Wm Braid White's
book, Theory and Practice of Pianoforte Building, 1906.

I believe it was also White that wrote about the need to reduce the width of the
bridge at the glue joint to allow the surface of the soundboard to more freely
"undulate."

Del

| -----Original Message-----
| From: pianotech-bounces at ptg.org
| [mailto:pianotech-bounces at ptg.org] On Behalf Of Ron Nossaman
| Sent: December 19, 2006 11:52 AM
| To: Pianotech List
| Subject: Re: Bridge Doglegs, was: Spreadsheet info / Jason Kanter
|
|
| I'm not convinced that grain continuity along the bridge
| length is remotely a big deal. I build bridges with open ended
| laminations at the doglegs. (photo) It makes it easier to jig
| up for a one off bridge, and I can make whatever is called for
| by the log progression of speaking lengths. If there is any
| tonal penalty for doing this, I sure haven't been able to
| detect it. This should be  doable in production too with few
| problems.
|
|
| > I am not entirely sure that there might not be a good acoustical purpose
| > served by minimizing the dogleg.   I am getting into dangerous territory
| > here, since I have no study to point to which would support this argument.
| > There must be some reason why the treble bridge is commonly undercut to
| > make the gluing surface with the soundboard a smooth(er) curve.  I'm
| > thinking that the more the long bridge snakes along the soundboard, the
| > more its capacity to transfer its energy to the board is inhibited. (Flame
| > suit on.  Go for it!)
| >
| > Frank Emerson
|
| I undercut the treble section and front of the treble dogleg
| to get the bridge footprint as far away from the belly rail as
| I practically can. Other than that, I haven't been able to
| detect any indication that the soundboard cares one way or the
| other if the footprint doglegs at the break. Just my
| experience. Anyone requiring absolute proof is going to have
| to generate their own.
|
| Ron N
| 

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