This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment 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 -----=20 From: Alan R. Barnard=20 To: pianotech@ptg.org=20 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.=20 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.=20 Alan R. Barnard Salem, MO ----- Original Message -----=20 From: Delwin D Fandrich=20 To: pianotech@ptg.org=20 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?=20 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=20 ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/93/64/06/08/attachment.htm ---------------------- multipart/alternative attachment--
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