[pianotech] Bridge pin locations help (image oops)

[Roger@Integra.net]

Ron,
I would have a tendency to disagree with your analyst. First, if a false 
beat was usually caused by a loose pin (which it frequently is) then there 
isn't a rational reason why string seating cures a major portion of false 
beats. What seems more rational is that the seating process beds the string 
against the pin and bridge to create a uniform termination during the entire 
circular motion of the string -- remember, strings rotate, not just move up 
and down.  In the situation pictured, the rotational movement of the string 
would indeed vary the termination length and/or create an "energy leak, or 
skip" past the termination sometime during the rotational cycle. That 
picture "screams" of an situation where the energy can't be uniformly 
reflected back into the string during the entire rotational cycle.

Your mention of using a screwdriver to temporarily "stake" the pin for 
testing is, in my opinion, suspect many times. When the false beat seems to 
be reduced or disappear during this test, you will, with close examination, 
find that you are not always hearing the effects of a more solid pin, but 
only the result of a dampened bridge cap, giving you the impression that the 
false beat has disappeared. This is not to say that the screwdriver test is 
an invalid test, but is to say that you may find yourself barking up the 
wrong tree.

Roger Gable

----- Original Message ----- 
From: "Ron Nossaman" <rnossaman at cox.net>
To: <pianotech at ptg.org>
Sent: Thursday, February 03, 2011 7:45 PM
Subject: Re: [pianotech] Bridge pin locations help (image oops)


> On 2/3/2011 9:33 PM, Mr. Mac's wrote:
>
>> That is something what you say about the notched edge.
>
> What we were all taught about this is wrong. The pin is the termination, 
> not the notch edge. If the pin is firm, the notch being too deep won't 
> cause false beats.
>
>
>> I'll be seeing the piano again this coming Sunday
>>     do what you say. And if it proves out, I got the CA glue.
>
> First, try the screwdriver test to see if the beat disappears when the 
> screwdriver is pressing on the pin opposite the string. It most likely 
> will, and will come back when the screwdriver is removed.
>
>
>> You're speaking CA thin, yes?
>
> Thin's fine. It might take a couple of applications to fill the gap, but 
> if the screwdriver test works, so will the CA. You can do it with the 
> string on, at pitch, and all that good stuff.
> Ron N
>
>