Mass loading - Re: Hail and fare well, was Re: Bridge Pins & NegaBearing

[Porritt, David]

Ron:

Thanks!  I had drilled 1/16" pilot holes down from above as I don't
trust myself to be able to drill from underneath and actually find the
bridge.  I enlarged that hole from above and put the weight on and it
makes a very nice difference!  I was just kind of reluctant to put too
big a hole in the bridge cap but it really doesn't look bad and if I
feel like it later I might plug it and put some Dag on it.

dave

David M. Porritt
dporritt at smu.edu
-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On
Behalf Of Ron Nossaman
Sent: Tuesday, April 25, 2006 7:15 AM
To: Pianotech List
Subject: Mass loading - Re: Hail and fare well, was Re: Bridge Pins &
NegaBearing


> I was working on an "L" here with a bad section in the "killer octave"
> that I wanted to help.  I used vice grips to find where I'd like to
put
> some weight and they really helped.  Unfortunately, where the weights
> need to go I can't get a drill because of the keybed extension and
> crossblock.  
> 
> Any bright ideas???
> 
> dave


Dave,
Nothing terribly elegant, but it's doable. The two problems 
are locating a hole from underneath that hits the bridge, and 
then being able to reach it to drive a screw. Locating the 
hole is easiest done by drilling down through the bridge from 
above, carefully avoiding ribs as well as you can. If you can 
then reach it from underneath with an offset or ratchet 
screwdriver, you're there. If not, a 12" aircraft drill can be 
used from above to drill a guide hole clear through the belly 
rail and keybed, or beam. This hole can then be enlarged as 
necessary from underneath to accommodate a long screwdriver. 
The small hole in the bridge cap is of little consequence as a 
trade off for making a killer octave more tolerable. The holes 
in the keybed and beams are of no consequence at all.

At least, that's what I'd do.

Alternately, you can eyeball drill from underneath, aiming at 
a spot on the soundboard between ribs, using the dowels as a 
guide, and hope you come close to hitting the spot after going 
through the beam or keybed, and that the dowels are reasonably 
centered on the bridge. This is doable too, if a little scarier.
Ron N