[CAUT] bridge-pin experiment

[Richard Brekne]

Hey Joe

The thing is you see... I started off by simply replacing with 
undersized pins that were loose in their entire respective pin holes... 
and that changed the situation.  That in itself clearly points out that 
something else (at least) is also at work besides the loose pin issue.  
Otherwise all three would display false beats... and certainly nothing 
would improve... but 2 of 3 did improve... one of these completely.

Then, coming to the soaked bridge pin holes.  The only thing that was 
essentially different in this before and after scenario is that the wood 
around the bridge pin holes had been saturated as far as the CA could 
penetrate.  I suppose its easy enough to figure out how much that is in 
a mock up... but I haven't done so...yet :) In any case, the old pins 
went back in every bit as easy (if not more so) then they came out.

The whole problem with idea that the bridge pin alone is the support for 
the string  is ... well. first of it ignores that the <<support>> also 
has a support as it were. That in itself is (should be) enough to point 
in the direction that the whole thing is more complicated then a simple 
single loose pin.  Then too... is the fact that the string vibrates in 
virtually every possible direction... and that the phase shift that is 
in the end responsible for the beat can be likewise observed in all 
directions.

 As cleaning up the notching is concerned.  The notching and string 
grooves were unchanged... I made sure and not fill up to the brim as it 
were.  Whatever soaked into the top area of the bridge pin holes did so 
from wicking up from below.  Transfering vibrations to the back side of 
the bridge eh ??.. I haven't really thought much along these lines... 
But when you first mention it... the bridge is not infinitely (or even 
close to it) stiff or massive.  On some micro level what you suggest may 
happen along with all else that happens. The bridge is moveing around in 
all directions along with the rest of the string termination and the 
string itself... some more easily then others. And its not like the 
bridge wood is equally dense... stiff...massive... whatever through out 
its entire interiour.  The area very close to the pin seems critical 
when it comes to false beating. But it definitely seems very much 
involved. 

But thats just my take on it.  I've never been one to accept 
conventional wisdom at face value without further ado. Regardless of 
where any given convention comes from.  I've looked at this time and 
time again and two things seem obvious.  1: CA works... for whatever 
reason... no doubt about it.  2:  Its simply got to be a lot more 
complicated then the loose pin idea allows for.

Cheers
RicB



        Hi Ric,
        Could it be that the CA, in addition to curing the looseness of
        the pin
        problem, also eases the transfer of vibrations across the bridge
        to the back
        segments, as well as cleanes up the notching?

        Joe Goss RPT



     > I agree that the addition of CA cleans up a lot of the classic false
     > beat... but I remain very unconvinced as to why.  Couldnt resist
    doing
     > my own experiment when I read the first post on this thread.  I took
     > three very badly beating strings on 30 year old Petrof that
    responded to
     > the screwdriver pressure,  loosened the string and  removed the pins.
     > First I put in very undersized new pins and tuned up again.... 2
    of the
     > three false beats got way cleaner... one came out perfectly
    clean... the
     > third was about the same.  Then I  removed the strings again and with
     > the undersized pins still in soaked the holes with CA... I mean I
    really
     > soaked them suckers.  I waited about 10 minutes and pulled the
     > undersized pins which and reamed out the holes to their origional
    size.
     > Then put back in the original pins.  Replaced strings, tuned up
    and all
     > three were clean as a whistle.  Strikes me that the addition of CA is
     > affecting the wood itself more then anything else.
     >
     > Cheers
     > RicB
     >