Curve on Bridge Bottom

[Ron Nossaman]

>
> >>>>>>>>>>>At this point I'm not convinced thats all there is to it. In a
free
> state the board is straight along the grain and in the example above I stated
> that. I have glued boards  into rims with no bevel in the rasten and no curve
> in bridge bottom (Hardman & Weber) or in the rim and these did not form but a
> smidge of this crown along the bridge line. How do I explain this?


Where's the rest of the information? Stiffness of the ribs, stiffness of the
panel, crown heights, etc. There are still a whole lot of possibilities here
other than bevel and bridge crown, all of which would affect the long crown. If
the rim was indeed on a plane (same height all around), and you had  nearly no
crown along the grain after installation, then you had nearly no crown along
the ribs either. How do you explain that? 


>
> >>>>Don't foget though that the treble and bass ends usually need some
> coaxing down at the ends which is also allowing the longer ribs to have more
> of the  effect you stated above.


I didn't forget it. This is what I'm talking about. I said up front that
forcing the board down on the rim forces the long crown to form. 


>
>  In this case it seemed even more so. If the rim were to be simply cut
> slightly different, asending a bit so to match boards perimeter at that tail
> then this effect would not occur and there would be no or nomminal crown
> along the bridge line.


It would take a little more than slightly different, but yes. Why would you
want to, and do you know of any piano where this was done? What has this to do
with crowned bridges?


>
> >>>>>>>> What I think would be of interest would be to attempt to measure any
> residual crown along the grain after the bearing goes on as Terry suggested.
> I think a thread could be pulled across the top of the board under the
> strings and then make some allowance for the top being thinned. Perhaps a
> comparison of that dimension with the rib compression too would be of
> interest.  


Since the rim plane and rib crown define this long crown, how can there be
anything but a direct correlation? 


>
> What would that tells us? Hey I don't know I'm not the expert just a casual
> observer.


Me too. I don't like the term "expert". To me it means someone who quit
learning many years ago when they had their shirt stuffed. Let's avoid experts
as much as possible and work this stuff out with our own brain cell(s).


>
>                                  Back to the salt mines
>>
>> >>>>>>>>>>>>>>>>>Dale>>>>>>>>>>>>>>>>>>>>>>>>>>
>


Me too two.

Ron N