[pianotech] wippen felt advice

[Dean May]

Is the key resistance throughout the stroke, or only at the end? If at the
end look for things that are binding, like damper wires against the stop
rail, balance rail pin against the back of the slot, felt square on jack
hitting catcher.

 

Just because you don't perceive excess friction by lifting the wippen, I
find that to be a very unreliable test. Disassemble the parts and test
flanges individually.

 

Check the depth of balance rail mortise in key

 

Sometimes you'll get excess friction with bad bushings/pins, so even though
they may be sloppy, you'll still feel excess friction with slight sideways
pressure on the keys. 

 

Test damper spring tensions with a Correx gram gage. Usually 20-30 grams is
more than adequate, measured at damper head. If it silences the string it's
enough.

 

Try holding damper off the string to see how that affects key resistance. 

 

Make sure hammer springs aren't binding or too strong. Try removing hammer
spring to see how that affects key resistance. 

 

Check jack spring tension. 

 

They may have replaced hammer or damper or jack springs with springs
excessively stiff. 

 

I would not recommend the use of DAG that someone recommended. Use Teflon
powder instead.

 

I have often suspected the wippen cloth like you, but have always found
something else to be the culprit. 

 

Dean

Dean May             cell 812.239.3359 

PianoRebuilders.com   812.235.5272 

Terre Haute IN  47802

 

  _____  

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Tom Sivak
Sent: Thursday, June 25, 2009 7:27 PM
To: pianotech
Subject: [pianotech] wippen felt advice

 


List

 

The piano is a Steinway upright from the 1870s. It came to me, refinished,
almost completely rebuilt, and nearly unplayable.  There is a lot of
friction, especially on some keys.  I suspected verdigris, but the action
centers were not the problem.  (It is verdigris free, and everything moves
freely.)

 

The problem seems to be the wippen pads.  The hammer moves with no
appreciable resistance when I lift the wippen with my finger.  Push the key
down and I have to use undue pressure.   The keys themselves need new
bushings, move too freely, and are not the problem, either.

 

The capstans are smooth and when I run my finger over the top there is no
stickiness, roughness, or anything would increase friction.  (They are the
big wooden dowel capstans.)

 

The wippen felt pads, though, are heavily dented, even though they were
replaced in the rebuild.  They are a white felt, they look to be an
appropriate thickness, but my theory is that the felt was too soft and thus
the dents are, at least, a part of the problem. 

 

I want to make sure I don't replace these with a felt that is also too soft.
How can one measure and compare the softness of felts?  

 

Or is there a specific brand/weight/etc. that you have used with success?

 

Thanks in advance for any advice you all might have,

 

Tom Sivak

Chicago

 

 

 

 

 

 

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