Inertia, was "Grand Touch"

[Michael Spalding]

Dean,

Think for a moment about the assumptions behind your statement.  Do you
assume the key material is homogeneous and isotropic?  Ever see a key with
3 or 4 closely spaced 1/2 inch leads with cracks in the wood connecting
some or all of the lead holes?  Text book formulae are one thing, the real
world is  another.  At the midpoint of a 1/2" hole in a 1" tall key, the
stiffness is reduced by approx. 12%.  Is this negligible, or can a
sensitive pianist feel the difference?  What about 2 holes, or 3 or 4? 
Worth testing on actual components, I say.

Mike


> [Original Message]
> From: Dean May <deanmay at pianorebuilders.com>
> To: Pianotech List <pianotech at ptg.org>
> Date: 7/13/2006 9:53:51 AM
> Subject: RE: Inertia, was "Grand Touch"
>
> The stress is all carried by the upper and lower fibers of the wood. Holes
> in the middle have negligible effect. Think I-beam. All the stress is
> carried by the upper and lower webs. You don't want to drill holes in
them.
> You can, however, drill through the connecting center web with no loss of
> strength.
>
> Dean
>
> -----Original Message-----
> From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On
Behalf
> Of Michael Spalding
> Sent: Thursday, July 13, 2006 9:31 AM
> To: Pianotech List
> Subject: Re: Inertia, was "Grand Touch"
>
> Jude,
>
> I think it's great thatyou will be testing this experimentally.  One
factor
> you might want to look at is how the lead holes in the keystick affect its
> flexibility.  It seems to me that a keystick with several large led holes
> close to the balance pin would flex more on a hard blow than one with
fewer
> or smaller holes further away from the balance pin.  Looking forward to
> hearing and discussing y our results.
> \
> Mike
>
>
> > [Original Message]
> > From: Absolute Piano <absolutepiano at comcast.net>
> > To: Pianotech List <pianotech at ptg.org>
> > Date: 7/12/2006 9:02:37 PM
> > Subject: Re: Inertia, was "Grand Touch"
> >
> > Thanks Vladan and all for all the info.
> >
> > There is a lot to chew on. My interest is in the practical application.
> Why 
> > is it that two keys with the same balance weight and the same front
> weight 
> > but leads arranged differently seem to me to feel the same?
> >
> > I ask because I had a customer that asked me to place all the leads
> closer 
> > to the front and to use less leads after I had already set up the FW to
> my 
> > specification in a new keyboard using a tower pattern nice and close to
> the 
> > balance rail. I went through all the trouble but as far as I or anyone
> else 
> > could tell the action felt the same.
> >
> > I'm in the process of building several action models to test the science
> as 
> > I am slowly digesting it so you are all being quite helpful.
> Unfortunately 
> > with reality hanging over me it may take awhile to report back any
> results.
> >
> > Best,
> >
> > Jude Reveley, RPT
> > Absolute Piano Restoration, LLC
> > Boston, Massachusetts 
> >
>
>
>
>