[pianotech] Knuckles Replacement - the details

[David Weiss]

Joe,

Thanks for the details.  Before you remove the knuckles with the fence wire
cutting pliers do you get them loose with heat or wallpaper remover or some
other method?

Thanks,

David Weiss

PS.  Any chance we could see a photo of the modified fence wire cutting
pliers?

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Joseph Garrett
Sent: Sunday, February 05, 2012 9:51 PM
To: pianotech
Subject: Re: [pianotech] Knuckles Replacement - the details

Just finished swapping out the 10mm knuckles for some 9mm ones. As I was
doing it, it occurred to me that the fine details might be of use to those
who have not done this job. So, here they are:
I removed the original knuckles with Fence Wire Cutting Pliers(slightly
modified<G>).  As I did, I cleaned the notches and removed any residual glue
from the shanks & mortises. I did this with Nicholson 4" files, one with the
sides made "safe", the other left as is. It turned out that the "as is" one
was .001" thinner than the "safe" one, which was used as the final thing to
clean out the mortise and size it. The "as is " one was exactly the
dimension of the mortise. <G> Once all the shanks were prepped, then each
individual knuckle was fitted for it's shank mortise and the nap of the
leather was determined. The nap needs to be smooth towards the end of the
shank and rough towards the centerpin. The "rosewood" of the knuckles is not
absolutely the same size, nor are the mortises of the shanks, so individual
"fitting" is needed. Once the knuckle was "fitted", it was then glued into
the mortise. I use modified clothes pins, (the spring type), to add just
enough pressure to hold the knuckle at right angles to the shank and in the
bottom of the mortise, without crushing the knuckle. At the same time as the
gluing process, I double check for damage from the removal of the other
knuckles. If found, I press glue into the
crack(s) and the clamping does a double duty. I have 16 of the clamps, so I
just pull from the first of the shanks, when I get to #16 I use #1. It seems
that the cold hide glue has set up sufficiently in this amount of time. The
work goes fairly quickly, even though I'm doing a bunch of things to each
one of the shanks, in the process. Once the glue is set, I clean up any glue
beads/smears on the outside of the joint(s). Of course, in the process, I
make sure the knuckles are in exactly the proper position in relation to the
shank/motises.
Hope that helps.
Joe


Joe Garrett, R.P.T.
Captain of the Tool Police
Squares R I