overcentering justified?

[Richard Brekne]

Bill Ballard wrote:

> At 11:15 AM +0200 8/23/03, Richard Brekne wrote:
> >Yes it does... didn't that have to do with the discussion about  Bob Hohfs
> >article... just how needed it is to think in terms of 90 degree rake and shank
> >parallel to the strings ?
>
> You're correct, and out from the microwave, it reappears as
> leftovers.

And, I might add... we are assured thus that it is not half baked  <G>


> At the time I said that the math to obtain all three
> (shank parallel to the string, hammer striking the string square, and
> hammer mounted on the shank square) involved nothing more complicated
> than trig. (The only difficult measurement is the angle between the
> string plane and the keybed.)

Point is that it does not take too large of an error in one or another measurement
to end up with a bore 2-3 mm off where you really want it. That is unless, I
suspect, you have practiced the routine enough times to be consitantly accurate
enough. This seems to be at least partially related to the origional problem
presented in this thread.  Ed's cute solution is measurement free so to speak, and
nearly fool proof. That being said, I would think doing things your way would be be
more conducive to a better understanding of action leverage principles as well as
solving the problem of bore length very nicely.

>
> I also said I'd be perfectly happy with two out of three (ie., a rake
> on the shank instead of a square mounting.) After all, the
> hammer/shank glue joint will survive hammer blows in a situation of
> "square-to-string" collision and raked mounting far better than it
> will the other way around.

I agree. Tho despite the inevitable filling away of some of that bore length over
time, I prefer a slight tendency towards overcentering then the opposite.


> This is not a situation where we're forced with a two-out-of-three
> choice (as with blow/dip/aftertouch). But given the mutability of the
> hammer bore (as Ed Foote points out, the puffing up a Renner hammers
> during the initial stages of voicing, and the inevitable reduction
> during successive years of filing), this issue may be academic.

Yes and no... depending on the degree and how things are maintained me thinks. If
hammers get so worn down that they are wayyyy off target then their rake is of
course superflous. But we know more or less what to expect ahead of time right ??
So we can at least to some degree take that into consideration while mounting
them... at whatever rake we want.

In anycase... Bobs article about action elevations presented the idea that the
hammer should be at 90 degree rake and perpendicular to the string at impact while
at the same time being perpendicular to the keybed. And while understanding his
proceedure for assuring as close a conformance to that ideal as any given piano
allows for is instructive, I dont really see the need for the condition in the
first place... at least not in the given context.

> Bill Ballard RPT
> NH Chapter, P.T.G.
>
> "When writing a mental note, first procure a mental piece of paper"
>      ............mental graffiti
>

Does this mean more or less... make sure you were in the right line when they
handed out the brains ?? :)

Cheers
RicB
--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html