Where's the engineer? - was string seating - was bridge caps

[jolly roger]

At 05:09 PM 4/13/01 -0500, you wrote:
>Roger,
>
>Interesting leap, and not off the wall at all.  I wasn't thinking about pins
>working up out of the bridge when I wrote that.  Does it really happen?  Or
>do they just get loose without moving up?  I wonder if any of the many
>different bridge constructions does a better job of holding onto the pins:
>One piece, vertical laminated with quarter-sawn cap, or whatever?
>
>Mike

Hi Mike,
             The more I think of pumping action, the more the appeal to
investigate. This has been on my mind since the start of this thread.  I
year or so ago I had some special brass bridge punches made up, and have
been tapping bridge pins to remove false beats, it seems far more effective
than seating strings.   I suspect that the pin moves and drags the string
with it, or the shock breaks the static friction, and the string drops into
position. Perhaps both.
On older pianos there is usually quite a bit of movement, perhaps lending
credence to the pumping hypothisis, but there are so many other factors.
Another observation, Baldwin vertically laminated bridges, seem to have
less bridge/pin related problems and movement than most pianos.  Adds more
questions than answers for me.
Some time ago, I mused about CA gluing the hole before repinning, my
thoughts were that it would reduce movement from humidity swings since the
end grain would be sealed and supported.  My next bridge cap I will try it,
and let you know 2yrs down the road how it works out. The glue could act as
a driving fluid, reducing heat and stress, from the installation.

Regards Roger