Foundry Castings

[gordon stelter]

Especially a Mason plate! ( I'm sorry to admit---but
the piano was irreparably flood damaged )And not just
due to added thickness. It was much tougher stuff!!!
--- "Paul Chick (EarthLink)" <tune4@earthlink.net>
wrote:
> Alan
> My dad ran a machine shop that catered to repairs
> for industrial equipment which included several
> foundries. I worked for him for about 11 years.  
> "Jerry" was the foreman for one of these foundries. 
> We watched him unloading used cast to be recycled
> for new cast.  He'd set the piano plates aside
> because they were "pig," first pour iron  He'd add
> some nickel to cast to give it a "little flex." 
> Brom's Foundry would add chromium to the mix to add
> hardness and pour "nyhard" (sp) castings for
> government contracts.  It was very hard, and hard on
> equipment.  Brittle cast was for low stress, low
> cost castings.  I'm sorry I can't relate any
> specific formulas.    Some cast machined very well,
> while other parts were a head ache.  They had hard
> spots and cavities.  Until epoxies came along, we
> had to bore out and press a steel sleeve in the
> bearing journal to make some repairs. We regularly
> junk old pianos and are amazed how difficult it is
> to break up the plates.
> 
> Paul Chick
>   ----- Original Message ----- 
>   From: Alan R. Barnard 
>   To: pianotech@ptg.org 
>   Sent: Tuesday, August 27, 2002 6:57 PM
>   Subject: Re: Foundry Castings
> 
> 
>   Cast iron IS brittle but it will not deform nor
> compress under stress and tension the way steel,
> aluminum, and other metals do. Nor does it expand
> and contract with changing temperatures as much as
> other metals. The key point is that it holds its
> shape and, most important, the critical string
> length dimensions. 
> 
>   I understand that cast aluminum was tried back in
> the 40's or so. It would sure be nice to find a
> different, lighter, less brittle material--then you
> wouldn't need such a heavy wood frame either. Every
> time I move a piano, my thoughts stray in this
> direction ...
> 
>   I'm guessing that a lot of the metal in the
> casting is just to make the plate "beefier" so it
> doesn't break so easily. 
> 
>   Alan R. Barnard
>   Salem, MO
>     ----- Original Message ----- 
>     From: Delwin D Fandrich 
>     To: pianotech@ptg.org 
>     Sent: Tuesday, August 27, 2002 1:16 PM
>     Subject: Re: Foundry Castings
> 
> 
>     And If I haven't created enough confusion yet,
> I'll toss out another one:
> 
>     Just why do we think gray iron is the best of
> all possible materials to use for piano plates
> anyway? What is it about gray iron that is so
> special? 
> 
>     We say it is extremely rigid -- but it is not.
> It's brittle. Is this an advantage?
> 
>     We say it has excellent internal damping
> characteristics -- but is this an advantage? Why?
> 
>     Right off hand I can think of only two
> characteristics that make it a particularly good
> choice for piano plates: [1] It is easy to machine
> and [2] it is cheap. Neither of these has anything
> to do with its performance in the piano.
> 
>     Del 
> 
> 
> 
> 


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