Curved Long Bridges

[Bill Ballard]

At 8:04 AM -0400 4/19/03, Farrell wrote:
>We were talking about a bridge from a piano with a well-designed 
>stringing scale and long bridge (what other kind would you put into 
>a piano?). There was an inherent assumption that hockey sticks 
>belong on the ice, and not in a piano! Yes, axe that curve off the 
>low tenor end of that stick and see how it balances.

Two points: Don't let your oeile get trompled. That upright long 
bridge is actually straighter than a Steinway O's. In the picture, 
the tenor bridge is the closest.

Nomer Doo: When you talk of balancing, I'm assuming that's along its 
length (as pictured). It's a long stick; find its balance point and 
both end will float in the air. I'm not sure that getting both ends 
to float in the air needs to be made any easier by editing the curves 
at the ends.

I just got finished realizing that any crown in a ribbed board is 
incidental, and not required for support of the string load. This 
meant that the underside of the bridge didn't need to be fitted to 
match board curvature (crown) parallel to the board and bridge. What 
remains is any extent to which the bridge may, in its path down the 
board, cross the "continental divide" (as 'twere), and thus need to 
have its bottom shaped to match this uphill/downhill contour. If this 
isn't done, I could imagine that the flat-bottom (for lack of a 
shorter word) bridge would would end up twisted in its cross section. 
Then the bridge would no longer be plumb to the string plane, but 
rather to the whatever point in the board's curvature you chose to 
measure it.

Maybe I pulled this thinking out of the oven too soon, maybe I should 
put it back in.

>BTW: Is that a hunk of granite on that table? Where did you get it? 
>$$? Sorry, I couldn't resist - its the old geologist in me.

That's right. One of two panels. That one 30"x60"x2.5", and the other 
42"x78"x(2.5~3.5") Rescued from an abandoned granite quarry in S. ME 
20 years ago. But that's a story for another time. Mark Dierauf, 
who's also on the list, might chime in on this one (seeing as how the 
statute of limitations has long gone).


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

"I go, two plus like, three is pretty much totally five. Whatever"
     ...........The new math
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