[CAUT] tight balancier

[David Skolnik]

Wimn'Ed -

I just went downstairs to make some rudimentary tests.  I would say 
that 6 grams would be the minimum I would choose to pin a rep 
lever.  I don't believe the bobbling you are experiencing has 
anything to do with the rep lever pinning.  As with the recent Wapin 
discussion, there are too many variables to easily ascribe the 
problem to just one issue.  The ability of the hammers to be held in 
check is affected by:
shape of tail profile
texture of tail surface (checkered? roughed? glazed?)
shape of back check profile
durometer of backcheck felt
tightness of backcheck leather
finish of backcheck leather (nap / no nap?)  If nap, orientation of said nap.
proximal relationship of tail and backcheck at letoff / drop
hammerpinning (too tight or too loose)
jack position at rest - too far forward will leave jack too close to 
knuckle after let-off, either allowing descending knuckle to bound on 
jack top, or the back radius of the knuckle will rub or otherwise 
push jack out of the way, stealing energy from the descending hammer 
that might prevent it from overcoming rep spring.
aftertouch- too little? as above.  Excessive? Jack can restrict 
movement of rep lever by putting too much pressure on felt in window.

I'm sure I'm leaving something out.

Bill Garlick showed me the potential advantages of 
tighter-than-standard rep lever pinning for repetition using a 
butterfly spring. The tighter pinning requires strengthening the 
spring which, in turn makes the jack faster.  If all the above 
parameters are addressed, I think you could pin at 8-10 grams and 
still have good checking.

But what do I know?

David Skolnik



At 12:46 PM 11/10/2006, you wrote:
>Ed
>
>this morning on the Concert D, I repinned about 2 dozen balanciers in
>octaves 2 and 3 from about 2 grams up to 6 grams. I had to reset the
>springs so that the hammer just barely moves up on release. The
>bobbling was less than before, but they still do not check on a medium
>to soft blow.
>
>I checked the resistance on the lowest octave, and they were at 6
>grams already. But they are also still bobbling on a medium blow.
>(They do check on a harder blow). Have you tried increasing the
>resistance to more than 6 grams in the low bass?
>
>Wim
>
>Quoting A440A at aol.com:
>
> > Wim writes:
> > << someone mentioned that a tight
> >
> > balancier will cause a hammer to bobble. My question is, does anyone
> >
> >
> > have a gram resistance measurement for this? <<
> >
> >     I like balanciers to be pinned about 4-6 grams, (just like the
> > jacks).
> >
> >
> > >If the balancier is tight, then the spring
> >
> > will need to be tight, which could cause the hammer to bobble. But it
> >
> >
> > is too loose, the spring would need to be loose, which could cause it
> >
> >
> > not to hold the hammer. <<
> >
> >      An excessively tight balancier will require an excessively tight
> > spring,
> > which will cause excessive friction between them.  If this is the
> > case, the
> > rebound from a very soft blow will not even move the balancier off
> > the drop
> > screw, causing the hammer to bounce.
> >
> > >>I have several pianos with bobbling hammers, especially in the 2nd
> > and
> >
> > 3rd octave. Before doing anything, I want to know what to do.  >>
> >
> >       I would try repinning the balancier on those notes, reset the
> > spring,
> > and see what happens.  I would suspect that the problem is in the arc
> > of the
> > tail and the angle of the back-check.  (I like to have the springs as
> > tight as
> > possible without being able to feel the hammer kick upon release from
> > the
> > back-check).
> > Regards,
> > Ed
> >
>
>
>Willem Blees, RPT
>Piano Tuner/Technician
>School of Music
>University of Alabama
>Tuscaloosa, AL USA