Bridge pin angles

[Ric Brekne]

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Hi Phil

First off, lets keep our shirts on here and not assume either is getting 
impatient with each other ok. Your note sounds like you are making some 
assumptions about my attidude, and I assure you they are as friendly and 
lighthearted in spirit as can be.

Secondly... let me address two points.  First the immediate one below.  
I asked you whether you are taking this position about side bearing 
increasing because no one has shown it to be true, therefor its an 
assumption, and one I dont buy into. Why ?? because the side deflection 
of the string simply does not change with dimensional changes in the 
bridge wood due to climate changes.  This sounds strange..?  Perhaps 
because one thinks that as the bridge suface grows they are pushing the 
strings higher on the pins and thus more sideways bearings ? But if you 
stop to think about things for a second one must see that it is the 
position of the bridge pin holes themselves that define the sideways 
deflection.  And they do not move sideways because of dimensional 
changes in the wood.   As the bridge expands  the angled bridge pin 
holes will tend to straighten out a bit, lessening if anything the 
actual angle of the bridge pins.  Not to mention that the pins 
themselves are being pushed upwards as it is claimed. So in actuality, 
you have bridge pin holes that do not change their relative position to 
each other... so no way of increasing side bearing there,...  and a 
stress on the pins themselves that go in the direction of lessinging 
their angle...   which if anything would decrease side bearing.

-------------------

>/Phil,
/>/
/>/So.. you are taking the position that upward pressure by the bridge 
/>/surface simply increases sidebearing and there by more friction, and 
/>/that the increased upward pressure by the bridge on the string is 
/>/more then countered by that increased friction ?
/
Phil responds
As the bridge pushes the string further up the pin then the 
sidebearing angle increases and static friction should increase 
accordingly.  It's probably not significant.  Ron mentioned an .011 
inch rise of bridge relative to pin.  I haven't run any numbers to 
indicate what the increase in sidebearing would be for that amount of 
rise, and I probably won't, since you don't seem to like numbers.

--------------------------



I love numbers !! But this is the kind of thing I mean when I caution against getting too
wrapped  up in looking at this from simply a numbers point of view.  If
one really sets about trying to prove oneself wrong, as per the
scientific methodology you described so well and I subscribe to 100 %,
then one has to look for these kinds of errors in ones own  basic
assumptions. And to do that one has to be open for the possiblity that
such errors can indeed occur.  Reading your many fine posts I know you
to be a person who is very capable questioning yourself in this regard,
just so you dont get the idea I am suggesting otherwise to your person
:)  In this case it is the assumption that sidebearing increases as the 
bridge sufaces presses upwards as humidity increases. 



So... as to the brass experiment.  It simply isolates the possibilty
for  crushed bridge surface syndrom out of the question, and if one
still finds strings <<climb>> the pins by subjecting the
piano to the same kind of conditions and use it otherwise
experiences... (and they do indeed climb)  then the crushed notch
theory doesnt hold by virtue of the fact that the condition can exist 
despite an obviously non crushed surface.


Pictures... grin... yes this would do a lot of good.  I'd get accused
of faking them by those who have already decided whats going on.  Those
same used about 2 minutes to discount Dons video without even having
seen it.  Besides... we all do these kinds of things for ourselves yes
?? I'm perfectly content to put my bit out and let whomever check out
what they want to and draw their own conclusions.


One final note.

The whole line of reasoning Ron N lays out lives and dies upon the existance of 
negative bearing when the string is off the cap.  Alls one has to do is find a
case of strings off the surface of the bridge while at the same time finding plenty
of positive bearing. This is easy to find.  New piano prep work shows this as 
conclusively as one could ever ask.  As far as I can see, Ron has simply described one
of the many things that can happen to a piano as it ages. But this does not amount
to far reaching grounds for claiming the uselessness of string seating. Not by any 
means.

Cheers
RicB






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