Action Ratio, was: More off the wall stuff

[Farrell]

Richard. What do you think of the method stated below:

So is it not best to simply measure how many units of hammer rise you get for each unit of key depression? I have two little blocks that slip under the key front. They have 5 mm difference in height. The taller one will meet the key with just a slight key movement (to avoid any funky stuff right at the immediate start of key/action movement, and the shorter one will meet the key before letoff. Place the taller block under the key front and depress key to meet block. At that point you measure the height of the hammer. Then you place the shorter block under the key and depress the key the additional 5 mm that the shorter block will allow. Again measure hammer height. The blocks allow a very precise 5 mm (or whatever you want to use) keystroke. You should be able to measure hammer height pretty accurately.

Is the convention to measure key height at the very front tip?

Seems to me this approach will eliminate any questions about exactly where to measure, etc. Does anyone see any shortcomings with this method?

Terry Farrell

  
----- Original Message ----- 
From: "Richard Brekne" <Richard.Brekne@grieg.uib.no>
To: <oleg-i@wanadoo.fr>; "Pianotech" <pianotech@ptg.org>
Sent: Sunday, January 19, 2003 7:45 AM
Subject: Re: Action Ratio, was: More off the wall stuff


> Where does all this mystery come from  ?
> 
> Davids formula is just another way of applying the law of leverages. Its
> easy enough to factor out the weight components of the equation and
> arrive at a more simple and straightforward equality for the action
> ratio. This is, and can never be anything else then the product of the
> ratios of the three levers.
> 
> There has to be consistancy between weight, distance, and speed in a
> levers ratio. Whatever the ratio of any given lever is, its has the same
> effect on these three. This is basic to the law of levers.
> 
> Any ratio that results in something else has simply got to be a measure
> of something else. Could be a valuable something else in another
> context, but just so..
> 
> Cheers
> 
> RicB
> 
> 
> Isaac OLEG wrote:
> 
> > Terry,
> >
> > The drawback of this method is that the leverage is changing  during
> > the stroke (more or less depending of the action setup, kind of
> > whippen, etc...
> >
> > At this moment seems to me that only David's method gives an evened
> > appreciation of what goes on for all the stroke.
> >
> > Regards
> >
> > Isaac OLEG
> >
> 
> --
> Richard Brekne
> RPT, N.P.T.F.
> UiB, Bergen, Norway
> mailto:rbrekne@broadpark.no
> http://home.broadpark.no/~rbrekne/ricmain.html
> 
> 
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