Bridge pins revisited

[Ric Brekne]

Hi folks

This is just a piece of information for our collective thinking on the general subject of false beats, loose bridge pins, grooves in bridge surfaces...etc.

I am pulling out the bridge pins in this old Bluthner today, getting ready to go down to Danmark where I and a friend will be making the new bridge for the instrument. 

The bridge pins after 150 years are for the most part quite snug.  No visual sign of elongation around the surface area either.  I need a good tight vice-grip and a solid twisting pull to get them out.  Probably this was a panel with little or no downbearing built into the design. Yet the angle and offset of the pins is quite usual compared to modern pianos so the clamping affect in the face of climatic changes is the same.  Solid beech (red I believe) bridge. 

There is almost no indentation after 150 years. Hard to measure of course... but certainly not more then 0.25 mm deep at their deepest.  In general they show the typical gradual lessening of the indentation at the middle of the bridge between front and back sets of pins.   Runing 5 lb fishing thread across the top adjacent along the de-pinned string imprint line shows the fishing line pulled taught in contact with the entire surface of the bridge including at the notch edges.  Ok.....this is a bit rough of a measurement... but revealing non the less.  The likelyhood of climate induced effective recessing of the notch due to the string straining against the surface of the bridge during periods of high humidity seems quite low given this particular bridge as an example.



Cheers
RicB