Function of the rim

[Delwin D Fandrich]

----- Original Message ----- 
From: "Farrell" <mfarrel2@tampabay.rr.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: September 01, 2003 4:22 PM
Subject: Re: Function of the rim


> Yes, that is likely the best answer of the four, but it think the real
reason is to have the pin at a very slightly acute angle to the string so
that a tight coil in maintained.
>
> Terry Farrell
>
> ----- Original Message ----- 
> From: "Avery Todd" <avery@ev1.net>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: Monday, September 01, 2003 4:58 PM
> Subject: Re: Function of the rim
>
> > >Here's another head-scratcher.  I didn't find any other clinkers.
> > >
> > >75) The tuning pin hole is drilled at a slight angle to the pinblock
> > >primarily in order to
> > >
> > >       A. create an orderly row of pins
> > >       B. resist the pull of the string under tension
> > >       C. create a better lock of the pinblock to plate flange angle
> > >       D. satisfy tradition
> > >
> > >In their answer key, the right answer is
.......................................... C
> > >

I would take exception to all but D. I've never had a satisfactory answer
to this question from anyone at any of the factories that employ the
practice. Finally, after making up a sample and a drawing it came to me. My
answer was published in the Journal some time back. Basically, the
pinblocks in certain pianos using three-ply pinblocks and with plates
covering the blocks which were drilled and pinned without any kind of
bushing surrounding the pin had a tendency to split. By using a relatively
small hole bored vertically in the plate with a pin angled back
sufficiently it was possible to let the pin rest against the plate at the
bottom of the hole while looking nicely centered at the top.

If you don't believe me, do the math, make the sample and draw the picture.
As to the idea that it helps keep a tight coil...well, look at the angles
involved. It does exactly the opposite. Or look it up in the Journal. When
pianos using this system are tuned the strings walk down the pin actually
spreading the coils.

Del