removing buzz from ribs/soundboard with CA

[Dean May]

>>Dean, How do you treat ribs and rim on a grand with CA glue? Please
describe the process.


I think Don Mannino was the first guy to tell me about this back in the mid
'80s as a warranty fix for some Young Chang grands that were having
soundboard/rim separation issues. It was also my first exposure to CA glue.
I was very skeptical, but he assured me it would work. And it did.

Remove lid, put moving blanket down and turn piano on its side. Use a
brush/vacuum to remove any dust/dirt coating on the ribs and soundboard rim.
If you don't, the dust will absorb a lot of your glue before it gets into
the joint.

I like to first mist on accelerator on the tops of all the ribs and all the
way around the soundboard. Without the accelerator you run the risk of the
glue leaving the joint before it sets up. 

Using a full bottle of glue, squirt the glue vertically and generously into
the rim joint around the top (you can't do this if the bottle is half
empty). The capillary action of the glue will suck it vertically into the
joint (it is an amazing thing to behold). BTW, if you are working on an
upright, do the same thing: start at the top rim of the soundboard and
squirt vertically. 

Then do the ribs: starting at the top apply enough glue to the joint so it
runs down the rib to the soundboard/belly rail joint (nomenclature police,
please advise). As you observe the bead of glue running diagonally down the
rib you may observe it disappearing into the joint. If this happens you've
located an air pocket in the glue joint, or some separation between the rib
and soundboard. Give it some more glue to fill up the pocket. If glue runs
all the way through and comes out the bottom of the rib, spray accelerator
along the bottom to set the glue up there and form a dam. In severe cases
I'll spray accelerator generously on the top as well to set the glue up
quicker before it runs out of the void. 

Try to run enough glue down the rib so that it will also cover the
sndbrd/belly rail rim joint. Then do the rest of the rim along the bottom
and back curve. 

Do a final misting of accelerator everywhere you squirted glue and wait 15
seconds. You don't want any unset glue running out when you set the piano
upright- DAMHIK. Then set the piano up and you're good to go.

If you have a case of severe separation you may want to use your favorite
method of pulling the joint together before applying the glue. If it is an
old clunker and you just want to eliminate the buzz it isn't really
necessary.

For an average piano, I use about 1 oz. For severe cases, 2-4 oz- sometimes
I'll even use thick CA if there is a lot of separation and I'm not pulling
it together.  

The same process will also work for loose bridges/pins, especially the
aprons on bass bridges. I've also spoken to a tech that claims it fixed a
grand with a dead section that apparently had a void underneath the bridge. 

I've done this procedure for 15 years now and never had a buzz return that I
know of.

If you are also going to CA treat the pins, go ahead and turn the piano
upside down and apply from the bottom of the tuning pin hole. I use no
accelerator for this as I want the glue to soak into the wood. You will of
course need to remove the fall board and action before you do this. Don't
use any more than 2 oz for this pin treatment. You'll waste glue or worse
(much worse), it will run out in places where you don't want it to. 


Dean

Dean May             cell 812.239.3359 

PianoRebuilders.com   812.235.5272 

Terre Haute IN  47802


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Steve Blasyak
Sent: Monday, May 28, 2007 10:42 AM
To: Pianotech List
Subject: RE: buzz

Hey Now,

Dean, How do you treat ribs and rim on a grand with CA glue? Please
describe the process.

Thanks in advance.

Steve

OC CA

Pura Vida