keybed spring

[David Ilvedson]

Dave,

You really need to report this to the dealer or manufacturer so they can fix the problem in the factory...!

David Ilvedson, RPT
Pacifica, California



----- Original message ----------------------------------------
From: "David Renaud" <drjazzca@yahoo.ca>
To: pianotech@ptg.org
Received: 2/24/2006 9:42:25 AM
Subject: keybed spring  


>  Korlore & Campbell, for a music school, one year
>old, tuned twice so far.

>   Call for sticky key. 

>   Key is rubbing on the key slip. 

>   Upon removal of the keyslip, I notice how tight the
>key slip screws are, and all the powder sawdust coming
>out with the screw. 

>   Upon inspection the key slip appears straight.

>   Placing the keyslip back, it touches the keybed
>at the ends, but there is a bow towards the middle
>with over a 1/16 inch gap at center. I push upward
>on the bottom of the keybed with my thumb only and
>watch while the keybed wood itself flexes up and down
>in the center and also observe the keys rising and
>falling. The keybed is a spring

>   I notice that with the key slip removed the entire
>middle of the piano has severly bubbling hammers.
>Putting the keyslip back stops the bubbling, but 
>the keyslip rubs the front of the keys. 

>  I determine that the keybed is warping. The downward
>pressure is forces the keyslip to torque
>towards the keys. Tight key slip screws were due to 
>torque of bending the keybed upwards. The dust
>coming out with the screws was the light material 
>developing stripped screw holes under the torque. 

>  Being a squeezed emergency appointment for a  sticky
>key , I comprimise by leaving one screw out so as not
>to torque the keyslip and keybed together so much,
>adjusted extra let off to eliminate bobbling hammers,
>and said I would e-mail a report.

>  I can not see a solution to this other then perhaps
>putting a strip of plate steel under the keybed to
>freeze it straight. With nothing but dust to screw it
>into, bolts through would be required. 
> 
>  I can bend the keybed about with my thumb alone. 
>How can one be expected to regulate that, the keybed
>itself is a mushy energy absorbtion spring. 

>  The first time I tuned this piano I was impressed to
>find a clean sounding chinese piano that was tunable.
>I am not so pleased afterall. This is bad for
>business, it smells of mechnical instability,
>callbacks, and unresolvable issues. I piano I actually
>can not work on mechanically  

>1) Steel plate?? thoughts.......
>2) How many have seen this.....other solutions

>  I will try to fix anything, but this looks like 
>soft, spongy warping material that can not be worked
>with. I feel it is a total waste of time to regulate
>it, come spring everything will have changed
>dramaticly. grrrrr

>   Somebody is going to think up a fancy technical 
>name.....accelerated keybed spring action.....and
>someone else is going to think it is a good idea and
>patent it.......sorry.....
> 
>                       Feeling dramatic
>                       Dave Renaud  






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