Keylead inertia and leverage (was Re: Ideal leading pattern:)

[Richard Brekne]

How neat that you actually took the time to do this... and you got other results
then I have noticed as well eh ? Well, that just means I gotta look at this a
bit closer and see if I can find out why I have observed this. I too will be
very interested in hearing if others come up with your result. Thanks muchly for
takeing the time to do this and letting me know what you came up with.

Grin.. now I got that itch just behind my left ear again....

Mike and Jane Spalding wrote:

> Richard,
>
> Interesting challenge.  So I did your little experiment.  Max weight was
> about 6oz of lead plus a plastic pony clamp at about 3" from the balance
> rail.  Min weight was the pony clamp horizontally at the end of the key
> hanging out beyond the key for maximum lever length.  Roughly a 4:1 ratio of
> weights and lever lengths.   Unlike your experience, I found the measurement
> process to behave exactly the same in both cases.  With not quite enough
> downweight, the key would start down, then gently stop with the hammer about
> 3/8 above the rest felt.  With steady gentle tapping on the base of the
> action model, the hammer would continue its rise to (not through) letoff.
> With small addition of weight, it would rise smoothly to letoff without
> tapping.  (My model takes extra force to get through letoff because it was
> put together from assorted previously owned parts, including hard flat
> knuckles).
>
> It could be that the mongrel character of the parts is also the reason it
> doesn't behave like yours.  On the other hand, it probably represents the
> real world of working pianos better than a model constructed of virgin
> Renner parts.  If anyone else has too much time on their hands, try this and
> let Richard and me know what happens.
>
> Mike Spalding
>

--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway
mailto:Richard.Brekne@grieg.uib.no