S&S Hieght of damper underlever tray

Horace Greeley hgreeley@leland.Stanford.EDU
Tue Oct 21 14:33 MDT 1997


Lorlin,

While others have offered a variety of excellent suggestions,
I think I'd first pull the pedal rod from its socket, and see
what's what.

It's easy to spend a great deal of time on one thing, only to discover
that (at least part of) the answer was somewhere else.

After that, I do think that starting with the key end felt makes good
sense, especially in the vintage you're looking at.  Unless you're
going to re-engineer the back action, the underlevers are too short
(and often rough on their bearing surfaces), and the tray is installed
such a way that the geometry actually _contributes_ to a variety
of problems - like involuted curves working outside/against their
range of efficiency (read "increased perceived touch weight"), and
premature, excessive wear (not only on the key end felt, but also on
the centerpins of the back action).

With respect to those who suggest it, and while I've done this a good deal,
I am reluctant to move immediately to increasing the thickness of the
back rail cloth.  If one is going to do this, one really should also consider
_how_ to compensate for the loss of key height.  It is not enough to simply
increase key dip, the basic height of the keys should be raised as necessary.
Otherwise, you not only (farther) throw off the ratios between the keys and
the stack, you also exacerbate the problems created by the poor design of the
back action to begin with, thus contributing to an even more Gordian
problem than you had before.

People with more math can explain this a good deal better than I can;
I have to keep going back to Pfeiffer.

Best.

Horace


At 09:31 PM 10/20/97 GMT, you wrote:
>
>
>The dept. head of the piano faculty recently complained about the "too
>sensitive" sustain pedal on the B in her studio.  Upon inspection I found
>damper lift from key to 
>begin well past 1/2 hammer blow distance.  There was very little lost motion
>between the underlever tray and the line of underlevers.  It became apparent
>to me that the underlever tray was just too close when in rest position.
>Raising the underlevers will make the damper lift from key even worse so the
>only thing I could see was to put thinner felt under the underlever tray.  In
>this situation, installing something as thin as understring cloth still won't
>lower the tray enough for a good 1/8" of lost motion.  Has anyone had any
>such problems with underlever tray height?  Got any suggestions other than
>planing the tray or something else on the drastic side?
>
>
>Thanks Much!
>
>Lorlin Barber
>Iowa State Music Hall
>
>
Horace Greeley

Systems Analyst/Engineer
Controller's Office
Stanford University

email: hgreeley@leland.stanford.edu
voice mail: 650.725.906
fax: 650.725.8014


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