Seiler Job

[David Love]

Richard:

You need to look at the force leverage first.  What is the key ratio and the
knuckle radius.  Those two will tell you a lot.  Assuming normal gluing
distance (130 mm), a knuckle radius of 17mm, and whippen leverage that is
normal, the key ratio needs to be not greater than .55 to accommodate a
medium hammer weight without excessive lead. Less is better but it seems
that below .53 you can begin to run into problems with dip or blow.  I would
try to resolve friction issues before you go any further.

David Love

----- Original Message -----
From: "Richard Brekne" <rbrekne@broadpark.no>
To: <pianotech@ptg.org>
Sent: September 06, 2001 9:35 AM
Subject: Re: Seiler Job


> Thanks Bill and Jim, I understand and was (am) tempted to install assists
for
> the rest of the action and go that way instead. One big thing makes me
back off
> at first glance... and that is the fellow who uses this grand likes it
heavy to
> the touch. I figure probably going with a BW spec of 40. At least I doubt
I
> should get under 52 grams down weight with this fellow. I interpret that
out of
> his declaration that he want to leave the weight as it is, and a look at
the
> data shows both heavy touch and a deal of friction (sluggishness to be
read in
> here ??)
>
> Anyways with that heavy a touchweight, and hammers starting off at around
12
> grams and curving down to about 5.8 grams I wont really need all that much
lead
> to begin with ??. Whadya think ?. I am guessing without really looking
closely
> at my sample data yet so maybe I am off the go in the wrong direction.
>
> Bill Shull wrote :
>
> Being so close to being able to do a support spring retrofit, I would be
> inclined to put springs in the rest of the whips, giving me the
opportunity
> to get rid of excess key lead mass, be able to put the mass where I want
it
> (the hammer), and get more control of balance weight (this before studying
> your spreadsheet...).  I am guessing the whips are ready, just need the
> springs and flanges/cord, which Renner might be talked out of, especially
if
> you need several sets.
>
> Bill Shull
>
>
> JIMRPT@AOL.COM wrote:
>
> > Richard;
> >  The operative word here should be "whippen *assist* springs". It is
when
> > these thingees are used for 'crutches' that problems stick out such as
your
> > "abrut" (sic: abrupt) shift in weights.  Just go ahead and address all
the
> > friction  issues first before you make any decision on disconnecting
these
> > puppies. Adjusted correctly they can be of significant benefit in an
> > intrinsically heavy bass section.
> > My view.
> > Jim Bryant (FL)
>
> --
> Richard Brekne
> RPT, N.P.T.F.
> Bergen, Norway
> mailto:rbrekne@broadpark.no
>
>