Key flex (was: Replacement Keys?)

[McNeilTom@aol.com]

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Most of our colleagues will be familiar with repairing keys broken at the 
balance rail mortise.  A slip of hardwood veneer makes a wonderful repair for 
this problem and also greatly stiffens the weakest part of the key.  If thin 
veneer is used, there is usually room for the increased width even if applied 
to adjacent faces of neighboring keys.  I like to make the veneer pieces long 
enough and tall enough to cover the sides of both key button and shoe.  The 
veneer should be trimmed flush with the key, button, and shoe for a nice neat 
job.  I like to use epoxy or Titebond for the repair.  CA is fast for an 
emergency repair, but its capillary action tends to get it into places where 
you don't want it - like soaked into the keybushings!  I have never done this 
repair to a whole set of keys, but estimate a very nice job could be done on 
the workbench in about a dozen hours.  I'd be inclined to try this before 
replacing the whole key set unless the keys have other needs mitigating the 
expense of replacement.
             -     Tom McNeil     -
Vermont Piano Restorations

"All men are equal before fish."   -   Pres. Herbert Hoover


In a message dated 3/6/01 11:50:37 PM Eastern Standard Time, jminor@uiuc.edu 
writes:


>     The piano is a D that suffers from "power loss" on some notes. In
> some instances, the harder you hit the key, the less sound you get! So, I
> pull the action and check to see if the tails are hanging up on the
> backchecks. I notice an unusual amount of flex in the key itself. Upon
> close inspection I see the balance rail buttons have been replace with
> what looks like poplar, not a strong wood. Some of the buttons "give" when
> you attempt to flex the key by pushing down on the key front while holding
> the hammer down, or holding the back of the key down. I think the keys
> have lost their strength and would like to test my theory by having a new
> set of keys made. The theory applies to concert instruments that are older
> and may have seen many years of heavy usage. I believe wood can fatigue
> when stressed to it's limits repeatedly.
> 
> John Minor
> University of Illinois
> 
> 
> 
> 





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