Key flexing, was "Inertia," was "Grand Touch"

[ed440 at mindspring.com]

It may very well render flexing at key leads irrellevant!  I can't recall the last time I saw a broken key that _did not_ break through the balance pin mortise.  Hardwood plates on top and bottom at the balance rail were common on great pianos of the 1920's, and somehow disappeared by the 1970's.  I'll be adding top plates to one I'm working on this summer, and am tempted to decelerate it as Ron did.

This method of pivoting the keys is inherited from harpsichords, where the stress is not significant. We should be inventing a new way to pivot keys that does not weaken them in the most stressed location.

Ed Sutton

Dean wrote
>
>The weakening effect of that balance rail hole on the keystick beam cannot
>be overstated. It is the weak link in the system. The effect of any hole
>drilled for leads pales in comparison. I suspect cracks between the holes
>occur not because of bending stress per se, but because of the internal
>stress placed on the wood by swedging the leads in holes too close together.
>
>
>But I've been wrong before. :-)
>
>Dean
>
>