wraped keybed

[David Ilvedson]

I would add to Wim's post:  

After you have raised the balance rail glides (if there are any...some old pianos don't) and before you do the balance rail bedding, check the front rail for complete contact with the keybed.  Striking along the front rail in front of keys with your hand or a piano hammer upside down, listen for knocking.  Mark with chalk areas that knock (you could mark the areas that don't knock if you prefer).  These spots are slightly higher than the keybed and consequently are coming down when struck above and making the knocking sound.  With a sheet of 220 sandpaper, lift keyframe and slip sandpaper under with grit upwards and pull towards you in the areas that are not knocking.  These areas are holding the chalked portions above the keybed and you need to remove keyframe (not keybed) material to bring it down.  IT OFTEN DOESN'T TAKE MUCH!  Make sure to continually check after sanding.  The goal is no knocking along the front rail.  

I'm sure others will add to this...

David I.



----- Original message ---------------------------------------->
From: <Wimblees@AOL.COM>
To: <pianotech@ptg.org>
Received: Tue, 27 Aug 2002 13:20:36 -0400
Subject: Re: wraped keybed


>In a message dated Tue, 27 Aug 2002 17:42:38 +0200, collin.s@skynet.be writes:

>> Hello list.
>> 
>> Is there a way to cure a wraped keybed in a grand piano ?  There is about 1 cm gap 
>between the front of the action and 
>> the keybed.  Should I add some material under the action frame?
>> Thanks for any idea.
>> 
>> Stéphane Collin.

>Stephane

>First of all, I think you mean warped, not wraped, keybed. (see misspelling). 

>A 1 cm gap between the action and the keybed is not an indication that the keybed is 
>warped. It probably means the glide bolts are too high in the middle. To solve this 
>problem, start by raising all the glide bolts so that they do not contact the keybed. (If you 
>want, you can remove the action, and see that the glide bolts are even or below the 
>edge of the keyframe). Then, with the action in the piano, press down on the balance 
>rail at one of the glide bolts. You will probably see the front of the keys dip down slightly. 
>(The easiest way to do this is to fulcrum your hand between the action and the pin 
>block.). You don't want this to happen. So lower the glide bolt until the keys do not 
>move any more. The next step is to hit the keys the side of your hand at the balance rail 
>with. Move the glide bolt either up or down, until you hear a knocking sound. This 
>indicates the glide bolt is just above the keybed. You want to turn the glide bolt down 
>just a few degrees more, so that!
> y!
>ou won't hear the knocking sound. That glide bolt is now int he correct posistion.

>You have to do this to all the glide bolts. Start this procedure with the glide bolt in the 
>upper treble, (not the last one on the right). Then do the next one to the left of that one. 
>When you have that one right, go back and check the one you did first. Repeat this 
>until all of the glide bolts are in the right place. (the last one you will do is the one on the 
>far right). 

>This will most likely solve your problem.

>Good luck

>Wim