evaluating sdbd. crown & bridge downbearings in a new piano

[Ron Nossaman]

>Hi Ron,
>
>Gee, I hope I'm not sticking my nose into a place it doesn't belong, but I
>had a thought as to how you might determine if a board was rib crowned.
>
>If you look at the grain of most ribs, it'll be pretty straight.  If the rib
>was machine crowned, I would think you would see 'end grain' popping up
>along the length of the rib on the side that was glued to the soundboard.
>(Assuming that the board is out and the rib is off.)  Not real easy to see,
>but I think it could be done.  Also, you could likely see some of the grain
>lines on the side of the rib.  That would also likely give a clue or two.
>Using the back of the rib (the side fartherest from the glue joint) could be
>deceiving, since not all of them were the same.  Some used ribs of the same
>thickness from end to end, and some used ribs that were machined on the top
>and flat on the bottom.
>
>But you probably already thought of all of this stuff long ago... :-)
>
>Have a good day,
>
>Brian Trout


Hi Brian, Your nose is just as welcome as anyone's. Come on in. Yes, I had
thought of that and decided that, since a 60' radius arc segment doesn't
make for much angular difference from one end to the other, and since the
ribs' grain meanders up and down some even when it is "straight", I would
tend to distrust that as a reliable method. I would think that the rib
that's thicker in the center, than at the beginning of the feathering, would
be a more reliable indicator of rib crowning, but not necessarily conclusive
either. That's why I asked.

  
 Ron N