Seasonal pitch change:

[RicB]

Hi Cy

I can believe that,  tho I did find a measurable pitch change when doing 
an experiment with strong (neodymn) opposing magnets under the treble 
section while back.
I agree, a good deal of real world measurements and experimentation.  
All part of a good days "woik"  as it were...

I should have a spreadsheet which charts expected changes of pitch for 
both soundboard rise/fall and strings climbing up the pins in a couple days.

On the side... I cant get over the fact that this string climbing bit 
has been a very large part of this discussion with no one seemingly 
wondering why string climbing is suddenly like magic not only possible 
but a matter of course. I cant count the times this has been plain 
discounted as possible due to the large clamping strength and friction 
levels involved when the string seating subject comes up. A couple 
interesting points on that subject matter have had light shed on them by 
this one I think.  First, that strings can and do climb pins after all, 
and secondly and perhaps more interestingly... a consequence of this 
climbing due to pressure from a swelling bridge surface is that the 
indentation becomes wider because of the increased sideways excursion of 
the string path on the bridge.  This has to be a partial explanation 
then for why the indentation is so much more evident towards the bridge 
edges then at the midpoint. The indentation is not necessarily so much 
deeper at the edges after all...,  as I have always assumed it was.

Cheers Cy
RicB


    At North Bennet Street, David Betts told me they once put a jack
    under a
    piano they were about to tear down, and put pressure on the
    soundboard from
    below.  Even with significant force, no pitch change was detected.

    Time for more Real World experiments, methinks...

    --Cy--