What's all this I hear about Inertia ?

[Fenton Murray]

We need a dynarepinertiameter, don't have one.
Fenton
----- Original Message ----- 
From: "Richard Brekne" <ricb at pianostemmer.no>
To: <pianotech at ptg.org>
Sent: Wednesday, October 08, 2008 12:52 PM
Subject: What's all this I hear about Inertia ?


> Hi Fenton.
> 
> Grin... you make a great case for Bob Hohfs approach to the whole 
> issue.  Still, both are simply tools these two different minds use to 
> help illustrate for us, and themselves a bit more of what actually is 
> going on... provide perhaps more justification for why the <<bubble>> 
> test works as well as it does.  Heck even Stanwood has a tool for 
> arriving at this... he simply got his gang to average as many pianos as 
> he could possibly measure... taking the mean area as a kind of 
> expression of player preference.  Given some 10000 instruments or 
> more... his averages fall into the field of statistical science and as 
> such he has pretty solid backing for his claim.
> 
> In the end tho... as you say... it comes down to feel.  Unless you are 
> out of the norm... say like a Horowitz or something... then your 
> educated feel should be a pretty good measure.
> 
> Cheers
> RicB
> 
>         > Agreed as far as it goes, tho you do change the key inertia
>        quite a bit...
>         > which several have offered opinion on. The only two formal
>        studies I know
>         > about the affect of key ratio are Dr. Stephen Birketts
>        treatise on the
>         > matter ( http://www.pianostemmer.no/files/key_balance.pdf )
>        and Bob Hohfs
>         > empirical experiments that bark up the exact same tree about
>        half way up
>         > and echo Stephens results quite nearly exactly. The effect of
>        key inertia
>         > / key mass on dynamic touch is quite interesting. The math in
>        Birketts
>         > paper requires a bit of study unless you are adept... but
>        with a bit of
>         > work most who have dug through their high school pre calculus
>        and physics
>         > stuff should be able to make sense of it easy enough.
>         >
>         > Cheers
>         > RicB
> 
> 
>    I don't think formulas will give me much here. A while back Nick G.
>    talked about tire shops spinning a mounted tire to balance it, it
>    just works better than the old static bubble.The best test for
>    inertia in the key is to play the piano making note of what feels
>    right. If you play a lot of pianos and take a peek at the leading I
>    think you can gain an understanding of what that lead feels like.
>    Too little lead has a weird fell as well. Just my opinion at the
>    present time.
>    Fenton
> 
> 
> 
>