Key End Felt

[Jon Page]

Most grands have the underlever sloping slightly into the key.
I've never scrutinized the assembly for this but I would imagine
that the underlever is parallel to the keybed or a little beyond center
when the key is fully depressed.

I know of a grand where the owner has constantly complained about
the pedal action. After trying numerous things which helped it, nothing
got to the core of the problem. Following a few Renner USA back action
replacements and the Bechstein key notching, I noticed the underlevers
on her piano are parallel to start. Maybe it is like playing 'out' of the
damper rather than playing 'into' it. ?huh  This was while installing 
spring assist wippens (removing 3lbs of lead).  I wanted to address this
and replace the backaction because the sostenuto tabs are a thin piece of
rubber glued into the top flange. She decided to live with it and enjoy the
ease of the action while retaining her desired BW.

Jon Page



At 02:41 PM 10/22/1999 -0400, you wrote:
>Avery writes:
>>I have some firm green Renner felt that seems to be about the right
>>thickness.  it
>>seems to me that the only problem it would cause, even if it _is_ too
>>thick, is to have to cut a little off the end of the damper wire.
>>   Am I missing anything? Any thoughts, warnings, etc.?
>
>Greetings,  
>I don't think we can have too many warnings when it comes to changing damper 
>geometry.  It is a subject that has fooled me in many way.  
>    There is a particular geometrical relationship between the arcs of the 
>key end and underlever.  The best relationship, from a friction standpoint, 
>seems to be like the "ideal" relationship of the capstan to its pad. i.e.
if 
>the range of motion is equalized around the common axis between centers, the 
>relative motion between the parts is minimized.  Also, the more steeply 
>angled the underlever, down toward the key end felt, the more friction.  
>Steep underlevers also dig into the felt unless polished. 
>     The underlever has its own "best height", determined by a number of 
>things such as cavity room, damper tray travel, sostenuto height, spring 
>pressure (if it has springs).  Combining these two "best" places is the art 
>of compromise.  I try for making the common axis between centers and contact 
>point occur at the beginning of the damper lift because I want the maximum 
>speed of underlever for any given key speed to occur at the point of 
>rest/contact.  I THINK it helps the damper seat faster to be returning to
the 
>string at this point.  
>    Also, the softer the key end felt, the less obtrusive the feeling in the 
>key at contact. (I may be obsessing, here.)
>Regards, 
>Ed Foote 
>  
Jon Page,  Harwich Port,  Cape Cod,  Mass.  mailto:jpage@capecod.net
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