Open face vs. closed face pin blocks

[Delwin D Fandrich]

----- Original Message -----
From: "Phillip L Ford" <fordpiano@lycos.com>
To: <pianotech@ptg.org>
Sent: August 15, 2001 6:11 PM
Subject: Re: Open face vs. closed face pin blocks


> ---
> Yes, the front flange does work as a beam.  More on that later.  Cast iron
> does in fact have tensile strength.  How much depends on the specific
> iron that is being used.  At the convention, I went to the Boesendorfer
> class and they mentioned that they use 35000 PSI iron.  This refers to the
> tensile strength (breaking strength) of the material.  While not high by
> high strength steel standards it is still a respectable number, even by
> metal standards.  Also, the iron is capable of giving (deflecting) as
every
> tuner knows.  One of the reasons it takes several tunings to stabilize a
> piano is because the plate is deflecting under the increased load.
> ---

I wonder about the 35,000 psi figure. When I was dealing with O.S. Kelly
from the mid-1980s through the mid-1990s they were using iron and a casting
process that tested at 24,000 to 26,000 psi tensile strength. Unless I'm
mistaken--and I could well be--O.S. Kelly is casting at least some of the
Bosendorfer plates.

Del