Lowell Gauge...morphing back to REVISITED

[Richard Brekne]

from the discussion at hand....

> 
>> If so, how is that function affected by 1) no contact (string climbing 
>> pin- see next quote  
> 
> 
> Strings don't climb pins unless something is severely wrong, but the 
> termination edge is crushed by cyclic wood dimensional changes with 
> humidity swings pushing the string up and down the pin. It's very 
> possible for a string to be resting on the bridge top and not be 
> touching the notch edge, but it hasn't climbed the pin. It's crushed the 
> cap. At that point, the loose pin flexes and flagpoles and the false 
> beat happens.
> 
> 
To be fair... this is less then a declaration of established fact, but 
rather ones musing on a probable explanation to the observable condition 
  of a string not being in contact with the front of the bridge. There 
are a couple problems with this idea, as seductive as it is on the 
surface of things. First... it cannot explain why a string that is 
positively deflected by the bridge at the termination point can also 
find itself in this condition. Secondly it relies on the assumption that 
the offset of the bridge pins creates a clamping system which is strong 
enough to force the strings to crush the bridge with seasonal changes, 
but not strong enough to keep the strings in contact with the bridge 
when the season again reverses and the bridge begins to shrink.

  >>   If it does not, does it have any function other than supporting the
>> bridge pin?
> 
> 
> The cap supplies the other half of the clamp, as well as supporting the pin.


I would rather say that surface contact between bridge and string serves 
as one element of the termination as well as supporting the pin. The 
clamping part goes without saying as the whole point of angled bridge 
pins is to hold the string down.

The location of that contact is far more interesting as a vibrating 
string will react differently (predictably so) when this part of the 
strings termination is before, behind, or at the same point as the 
bridge pin itself. Also the degree of the pins angle can influence this 
relationship, a fact that Wappin utilizes in his vertical bridge pin 
solution.

>> Are you saying that a string riding up a bridge pin would require BOTH 
>> negative downbearing AND near-straight bridge pins?  
> 
> 
> Probably, in a typical situation. It would take a whole lot of negative 
> bearing to pull a string at a 10° side bearing up a pin that's slanted 20°.
> 

Again... this simply does not account for the observble condition of 
strings riding up the bridgepins when there is positive downbearing also 
apparent.
> 
>>  In any case, it's hard for me to believe that you have not 
>> encountered innumerable examples of strings which visibly settle 
>> downward when tapped (gently). 
> 
> 
> Of course. But it's because you're inducing a curve into the string to 
> force it down to the crushed bridge edge by tapping, not because the 
> string has climbed the pin. 
> 

See above. If the side bearing is enough to cause the string to crush 
the bridge, then it sure as heck should be enough to keep the string 
clamped solidly to the bridge... regardless of the near insignificant 
(in this regard)amount of negative bearing this indentation can account 
for. And that says nothing about the case of positve downbearing.


> 
> 
>> My problem with the concept and terminology of "clamping" is that it 
>> encourages an image of the string exerting a vertical pulling and 
>> pushing force upon the bridge, which I believe is inaccurate.
> 

The string pushes and pulls, and in general yanks around the bridge in 
any direction of any of the vibrational modes the string has to offer. 
Both transverse and horizontal.

> How can you reconcile this belief with the belief that strings climb 
> bridge pins? What supposedly gets them up there? Believe what you like, 
> but the string does exert a vertical pushing and pulling (or lesser 
> pushing) force on the bridge. 
> 
> 

That we havent found a satisfactory explaination for the condition, says 
nothing about its existance. People see strings up the pins at the same 
time as being able to measure positive down bearing all the time. Ever 
since I first came across this  <<theory>> I've been taking the time to 
check this out closer and find way to many "pin rider" examples where 
the indentation in the bridge is not below the string line angled 
directly down from its top deflection point to the front termination 
point. What we have here is just another unsatisfactory explaination.

Cheers
RicB