knuckle orientation

[Dave Nereson]

----- Original Message ----- 
From: "Tom Driscoll" <tomtuner@comcast.net>
To: <pianotech@ptg.org>
Sent: Wednesday, March 24, 2004 8:18 PM
Subject: knuckle orientation


> List,
>
>             I have a set of Abel knuckles ---
>
> rollers to you guys on the other side of the lake--- to install.
>
>             My question is concerning orientation.
>
>             The leather is marked on one side to identify the grain, but
> I can't discern which way to glue them on.
>
>             I know the jack returns with the grain for smoother return
> but I can't feel the difference
>
>             My compatriots please advice.
>
>             Thanks
>
>             Tom Driscoll
>
>     Ah, the age-old debate.  At least they finally took it off the PTG
written exam, since the question was still being debated in the pages of
recent PTG Journals.
    There are those who argue that the nap should favor the return of the
jack in getting back under the knuckle (in which case the jack pushes
against the nap upon let-off, but then again has some "tooth" to dig into
while pushing the shank/hammer to the string).  And there are those who
argue that the nap should favor the jack when it lets off, that is, that the
jack should have the least resistance possible when escaping from under the
knuckle (but if the nap is thusly oriented, then the jack rubs "against the
grain" when it has to get back under the knuckle).
    I personally don't think it makes a dang bit of difference because the
"grain" on most knuckles isn't all that pronounced.  Even when trying to rub
it both ways to see which way it lies, it's sometimes difficult to tell.
    However, for consistency, you should install them all the same way
(sometimes holding in the light just right and rubbing the leather this way
and that will show you which way the nap lies).
    I just now went out to the shop and checked different makes of grand
shanks and two upright butts.  They all favored let-off, i.e., the nap lies
in the direction the jack travels when letting off.
    --David Nereson, RPT