Curve on Bridge Bottom

[Greg Newell]

Terry,
         Well now maybe in your last line you have something there. I do 
tend to over think things sometimes. Kind of like purchasing good equipment 
... I only want to do this once. Perhaps there are just too many unknowns 
for me and I should indeed just jump in there and have at it.

Greg


At 09:53 AM 5/5/2002, you wrote:
>Ok, now for a serious response, aside from thinking clamps   ;-).
>
>Align your rib clamps on a table, with all the centers along a line. You 
>can put your board in there and glue on your ribs as is.
>
>An alternative is to look at that and say, yeah, but my bridge line 
>squiggles. So to compensate, you move a few of the clamps this way and 
>that way so that the lowest point (ribs/panel put into clamps 
>up-side-down) in the cauls now follows the horizontal long bridge line. 
>Yes! This will make for a better bridge-to-crown-apex alignment!
>
>Maybe not.
>
>Glue in your ribs with this clamp arrangement, and glue on your bridge. 
>Picture what you have done to the ribs that are in the area of the 
>tenor/treble break - they go from the curved side of the case to the 
>forward bass corner. You would have moved these clamps toward the forward 
>bass corner of the board, and that would leave that rib end up a little 
>higher - great! That way the rib end will set on the inner rim more 
>willingly. But I suspect what will actually happen is that when you take 
>the clamp off, the panel will simply cause the rib to rotate end-to-end. 
>The rib end at the forward bass corner will go down and the rib end 
>against the middle of the curved treble area would rotate up. I think you 
>will end up with the board just the same as if you had left the clamps in 
>a straight line.
>
>Now when you go to put the board in the piano you will find that as you 
>squish the board onto the inner rim, you will note that the forward bass 
>rib ends need to go up, and the ends along the curved side of the rim need 
>to go down.
>
>I'm writing this and curves and rotations and moving clamps are swirling 
>all through my head. I don't know that anything I have said makes any 
>sense or has any merit. Too much bending wood here. I have sent this post 
>however, perhaps just as a statement of how complex trying to understand 
>all the dynamics of curved ribs and flat panels and bent panels and curved 
>bridge bottoms and curved inner rims, rotating bridges, rotating ribs, 
>etc., etc., are. Yikes! I think I need to finish my clamps and get some 
>spruce and start cutting and gluing and observing!
>
>Maybe the bottom line is: Do it! Shut up! Don't worry about it! And see 
>how it turns out. If it is bad, do something different next time.
>
>Maybe I got too much think in my clamp.  :-)
>
>Terry Farrell
>
>----- Original Message -----
>From: "Greg Newell" <gnewell@ameritech.net>
>To: <pianotech@ptg.org>
>Sent: Sunday, May 05, 2002 2:30 AM
>Subject: Re: Curve on Bridge Bottom
>
>
> >
> > Terry,
> >          Could you please explain this a little more. I can't visualize
> > what you mean.
> >
> > Greg
> >
> >
> > At 09:29 PM 5/4/2002, you wrote:
> > >"wouldn't all the ribs just rotate end-to-end and even out after you take
> > >the think out of clamps"
> >
> >