Hello
Thanks Don, good stuff to chew on.
I will try negotiating my Steinway problem with the rep levers pining.
Also some tonal experiments with small pin-much cloth vs. larger pin
less cloth, both at the same friction level would make an interesting
little experiment. Rep. levers pin eh.....have not gone there these last
two decades......thank you. Some food here for a future chapter meeting.
Got to love as well as hate this new technology.
Communication....., what a concept.
Cheers
Dave Renaud
----- Original Message -----
From: "David Renaud" <drjazzca at yahoo.ca>
To: "Pianotech" <pianotech at ptg.org>
Sent: Monday, January 05, 2009 8:20 PM
Subject: [pianotech] Kawai parts - response
> 1) A couple manufacturers are opting for "lower friction" in their
> flanges.
> Why, what is the argument in favour of this?
>
> I can think of reasons why this becomes troublesome. The lower the
> friction in a grand hammer flange the more narrow a window of opportunity
> there becomes for the rep' springs to be "just right." A brand new
> Steinway comes to mind with the new treated bushing cloth designed for
> lower friction. Rep' levers would collapse under hammer weight and fail,
> and with the very slightest bit of added tension jump.....30 swings is
> just too loose by any measure. It seems to me that if a company desires
> lower friction they are narrowing the manufacturing margin of error as
> well. If a hammer flange is 2gr or 4gr I can adjust so it works, but if it
> is designed to be 1 gram, it had better be one gram not .6 less or it
> fails.
>
> So I am curious, and open minded about it. Why lower friction in
> flanges by design?
There are a couple of factors that cause most manufacturers to set the
flange friction low, I think.
- Pianos are made for all parts of the world, and action centers vary with
humidity. If the friction is set to be ideal for a given part in 50%
humidity, it will be a little too loose in 20%, and too tight in 90%. To a
manufacturer complaints of sticky notes are much more serious than are
complaints of loose centers; thin tone in Calgary tends to be put up with,
but non-repeating notes in Miami or Houston are not tolerated! In either
case, there really is no way to set action centers to have "correct"
friction in all parts of the world, so the most reliable compromise is used.
- Another factor is action performance and tone. In my action center
seminar (which I am giving at the California State and the PTG Annual this
year) I talk about why we need friction in the action, and what the ideal
friction is for hammer centers. It is my opinion that pianos would perform
and sound the best with close to zero friction in the hammer centers, IF the
bushing could be firm enough to keep the hammer under tight control. For
example, Teflon action centers, in my opinion, made pianos sound and play
really, really well, and they were originally designed to be pinned with 0 -
1 grams friction. Of course, we all know what happened with them, but it is
still my feeling that as long as you don't mind changing bushings, Steinway
pianos with Teflon bushings really had great sound.
Since we have wool bushing cloth in the action centers, though, we need to
have more friction at this location in order to make the bushing firm enough
to control the motion of the parts. So we pin for 2 - 4 grams friction if
the cloth is of good quality; 2 grams when dry and 4 grams when humid. When
it gets extremely dry it might drop to 1 gram, which might cause the tone to
get weak.
In the case of your spring regulation problem, the solution is usually to
add friction at the repetition lever. This gives you control of the spring
so that you can set it strong enough to repeat well without making the
hammer too jumpy. I like to pin for 4 - 6 grams of friction measured at the
drop screw pad on the rep lever (spring disengaged, of course), which is a
very tight feeling action center. This will not cause any slowing of action
performance or additional touch resistance that comes from adding friction
to the hammer centers.
> Now for another matter of opinion............
> How large a required pin in a flange is too large for a new piano?
> 22.5 in a 6 month old piano should have a new part? 22, 21.5??? How
> enlarged is too enlarged a birds eye are deserves a new part while
> under warranty. I know this is subjective, and I will make my own
> determination in the end, but others opinions will weigh in.
Sometimes we piano tuners can worry about things on principle, when there
may not be any reason for concern. I know I have been guilty of this at
times.
Most new hammer flanges put out today (Kawai, Yamaha, and I think Renner)
start with fairly large pins, not the old #19 that used to be common. This
is done to create a thin, firm bushing, and also because the larger pins
feed through automated machines better. It doesn't worry me to put large
pins in an action, as long as the parts function well and you still have
bushing cloth in the hole. It's not as if they need to be changed every few
years - once they are fitted properly, most actions do not need repinning
very often. The last time I checked, Kawai upright actions are built with
#20 or 20 1/2 pins in most parts, so if this upright you are working on has
larger pins I would wonder what is up.
There was a time in the 80s when I was taking new actions from a well known
piano company, wet-sizing the bushings in the hammers centers, then taking
out the factory #19 pins and replacing them with #20 or 20-1/2. The
difference in tone and performance was amazing, because the original
bushings were too thick and spongy.
Hope this helps.
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