>Those explanations involving eventually compressed punchings make sense. >Charles Except that the balance rail punchings compress faster than the front rail and you still end up with the same loss of key dip whether you started with a crowned level, or a level level unless you allowed for extra dip in the center, which you could do as easily (or not) with a crowned level as with a level level. That would make it a visual concern, since a convex surface looks flat, where a flat surface looks concave. Actually, the Steinway keybed is supposed to be crowned slightly, so the crowned key level is theoretically parallel with the keybed. Ron N
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