Moment of Inertia of grand action parts.

[Richard Brekne]

Hi Mark, and John

Mark Davidson wrote:
> 
> I would say the
> work already done suggests that small variations in SWR are probably of more
> concern than small variations in key MOI.

This point is one of those that still bothers me a bit... and tho I have
yet to sit down and look closely enough at the posts that speak to
reflected MOI, it seemed they were pointing in the direction of the
SWRatio and the Dynamic <<heavyiness>> of the action were rather
independant of one another. Perhaps I have misunderstood and will have a
clearer picture when I get a bit of time to go through John and yours
posts on that matter.

In anycase.. it would seem to me that on the one hand we have come to
the conclusion that  key inertia is so overshadowed by hammer inertia
(and perhaps by the SWratio as well) in regard to the overall dynamic
touch of the action, that it is almost not worth bothering with. Yet
anyone who has done more then a few actions with precisely alligned
Front weights would probably report that this same even key to key curve
of FW's based on consistant lead patterns is instantly appreciated by
the pianist. This feedback from pianists would suggest there is
something wrong with the model of action dynamics that suggests
relatively small variations in key inertia are meaningless.

Perhaps this may be a result of the real average level of play pianists
employ, and we still havent gotten into dealing with just how hard the
pianist on average drives the instrument. 


> 
> Usability will require that someone do much work up front in order to make
> and keep such a system usable for the rest.  This is not work that the
> typical tech has the time or inclination to do, but that doesn't mean it's
> not doable or that people will not use the results if they are made
> accessible and offer the opporunity build a better piano.

Well... that is essentially what David Stanwood did, and does with his
PTD system. His recommendations are in  no small part bassed on averages
and means observed in hundreds upon hundreds of sampled pianos. In
essence.... he recommends what appears to have been the most commonly
used configuration through the last 100 years or so. 

> 
> -Mark
> 

Cheers
RicB