Inertia, was "Grand Touch"

[ed440 at mindspring.com]

Mike-

My assumption is different from Dean's.  I imagine the top half of the key serves as a tension member of a two part beam, the bottom as a compression member.  Because of this, I place new leads a little below the  exact center of the key stick.  I also assume that to whatever extent the lead may allow more flexing of the key than plain wood, it will occur more when the lead is closer to the balance rail.

Your comments?

Ed Sutton

-----Original Message-----
>From: Michael Spalding <spalding48 at earthlink.net>
>Sent: Jul 14, 2006 5:57 PM
>To: Pianotech List <pianotech at ptg.org>
>Subject: RE: Inertia, was "Grand Touch"
>
>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 
>> >
>>
>>
>>
>>
>
>