Tuning pin torque

[Delwin D Fandrich]

----- Original Message -----
From: <Duplexdan@AOL.COM>
To: <pianotech@ptg.org>
Sent: May 06, 2002 3:33 PM
Subject: Re: Well-Tuned Duplexes (was!Re: Songwriters, ect.)


> The second point I'd like to mention was an experiment i did on the NEECSO
A
> in response to Shawn Hoar's grave concern about weakening the pinblock by
> turning the tuning pins down about a quarter turn,  80 degrees, which I
find
> necessary in order to move the duplexes with accuracy and ease. Shawn is a
> notable rebuilder and his concern deserved my serious concern so I
borrowed a
> torque wrench and  took sample unison readings from five notes from the
> section I was working on. Lowell Wakker was present and helped me read
some
> of the numbers. I was a bit more than surprised to find that there was
zero
> average  variation of torque readings before and after the procedure. In a
> few pins the reading lowered from 138 to 137 and in a few others the
reading
> actually went up to 140, probably from the resetting of the pin. Out of 15
> pins the torque on 11 or 12 was exactly the same.

---------------------------


Dan,

Before you make the mistake made by so many 'researchers' in the field and
assume your results are gospel for the industry, you might want to check a
few other types of pinblocks. I did some testing on this a few years back
and, while I don't remember the specifics, the basic process included
driving the pins home with an air hammer, turning them four turns to
simulate stringing, letting them 'age' for a few days, backing them out one
turn and finally putting them back to their original position. After all
that we tested them for both torque and feel.

One generalized result that stands out in my memory was that the type of
block construction had a considerable effect on the residual torque. As
well, we worked only with Nippon Denro pins and it may be that other types
of pins would also give different results.

Your results are valid for the specific block and pin configuration found in
the piano you were working on at that time. They may not be for some other
block/pin combination.

Del