plate reaction was Re: Pitch Raising to A440.......Or Not?

[Ron Nossaman]

>This makes me wonder about the nature of castings; how long does the plate
>continue to flex after a major pitch raise ?
>
>Sid Blum

As far as I know, it doesn't enough to be a factor. The vast majority of
plate deformation happens while you're changing the loading during a pitch
adjustment. The long term changes will have more to do with string
rendering and segment tension equalization and wood creep. Again - as near
as I can tell. If the plate kept flexing and compressing after you were
done messing up it's loading balance with the tuning process, a piano with
as light a plate as an S&S D wouldn't be tunable at all, and that doesn't
seem to be the case. Besides, if the plate kept deforming under tension
enough to mess up a tuning some time after it was finished, wouldn't they
all eventually pull themselves into a little ball? A plate adjusts to the
tension changes as they happen - or breaks.

I hear comments like "It's still drifting", after a tech has made a first
pass and the piano is still 10 cents low. No, it's not still drifting, he
just didn't overshoot the pitch enough. 


Ron N