[ Craig Brougher wrote in 000305 MMD: ]
> Curing piano plates outdoors was extra insurance for this at one
> time. Let a plate sit outside and rust awhile, and much of that
> built-in stress can be distributed a little ...
Aging the cast iron is done to allow for uneven stresses that cause
warping, and possible cracking. It does nothing for the iron other
than allowing the manufacturer to weed out improperly stressed pieces.
Green iron is not stable, and if machined too quickly, will only warp
> Regarding my one broken piano plate, I brought the plate to a fine
> welder in three pieces: two very large sections and one segment.
> He brazed it back together, and promised it would be three times
> stronger than originally. It worked wonderfully, and the piano is
> still being played. I asked about cast iron rod. He said simply,
> "It doesn't work. Here's how you do it."
With due respect, the only proper and proven way to prevent
recracking is to heat the piece in a furnace, and torch weld it with
like material, cast iron rod. No reputable restorer of cast iron does
otherwise. Without this process, and proper execution, the piece
_will_ crack again. If not now, later. Failure to heat the piece,
and then cool it properly only creates another set of stress problems.
Your friend may be thinking of electrowelding.