Curved Long Bridges

[Bill Ballard]

Ron, Terry,

Thanks for straightening me out.

At 10:44 PM -0400 4/19/03, Farrell wrote:
>What on earth is an oeile?

As in trompe l'eoile, French for optical illusion.

>Most (I think likely all?) well designed piano scales do not have 
>any sort of a hockey stick curve at the tenor end of the long 
>bridge. It gets fairly straight in that area. The curve to the 
>bridge is in one direction only.

Agreed, as in Ron's .jpeg. That doesn't prevent the curved tenor end 
of the long bridge from showing up in the pianos from famous makers 
who should know better.

>Put the pencil under the middle of the arc, and the mid section of 
>the arc lifts up, but the two ends remain in contact with the 
>surface of the table or whatever it was laying on.

Agreed. Transfer an arc created on the surface of a sphere to a plane 
and it will lay flat.

>>  I just got finished realizing that any crown in a ribbed board is
>>  incidental, and not required for support of the string load.
>
>Where did this come from? The crown is usually designed in, not incidental.

My apologize to you both. I meant to say "crown parallel to the grain 
of the board".

At 10:03 PM -0500 4/19/03, Ron Nossaman wrote:
>You're assessing all this from the pathological example of your 
>bridge sample. Go through it again with the picture of the bridge I 
>sent, and it will make more sense.

Just as you said. The original long bridge used as a caul/form for my 
lamination went into the wood stove long ago, so there's now way of 
telling whether my lamination has crept back straight of the last 25 
years. But as is, it is still straighter than this Steinway O long 
bridge which has a curve at each end, in opposite directions. Which 
begs the question, has anybody rescaled the Steinway O (and all their 
other scales which have this fault) to produce a straight tenor end 
of the long bridge?

Thanks for not leaving me out in the middle of the road. Once a Boy 
Scout, always a Boy Scout.

Bill Ballard RPT
NH Chapter, P.T.G.

"May you work on interesting pianos."
     ...........Ancient Chinese Proverb
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