22 March 2009

Pouring molten metal to cast organ pipes

"At Bedient Pipe Organ Company, we cast the lead for our pipes. Basically the guys are spilling molten metal onto a fireproof table to form lead sheets. It only takes moments for the metal to cool enough to be rolled up and removed from the table."
The following notes are excerpted from the discussion thread at Neatorama:

"the alloy is lead, tin and antimony. also called babbit and is used for bearings in high speed, high load machinery. i have poured and scraped many many babbit bearings"

"I think the very base of an organ pipe (where it comes to almost a point) is solid lead for various reasons (weight, balance, forming a good seal, ease of soldering & removal). The lead content in the pipe itself was necessary for tuning. Although the note is determined (as Pythagoras showed us) by the length & diameter of the pipe, some fine-tuning becomes necessary, especially when so many pipes are involved. This is done by cutting three sides of a rectangle near the base of the pipe and peeling it down while someone plays a chord including the note you’re tuning. (It peels like a sardine tin; the lead content makes it soft enough for this.) The incision can be made larger or smaller by rolling it down or up."

"My dad was an organ builder, as was his father. My dad’s pipe maker was in Alliance, OH. Yes there is lead in those pipes. Each pipe maker has a preferred alloy to get the preferred tonal quality. For example: a Diapason from pipemaker “A” will have a different tone than one from pipemaker “B”"

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