Crown in Key Bed

[Farrell]

I'm no expert on piano designs, but you could likely tell pretty clearly by
using a nice 4-foot straight edge and laying it across the keybed in the
back, in the middle, and across the front, and then also from front to back
(as you apparently did) in the middle and at the two ends. I should think
that if it were designed, the curve/bow/whatever should be regular, i.e. the
whole front would be curved down, or something like that.

I'll bet that either the front of your keybed has sagged in the middle, or
the middle portion (front to back and side to side) has bowed up. I can't
imagine anyone designing a sag in the front center, or a bump in the middle!

Sounds like a good thing you have a flexible keyframe! Don't bother wasting
time with bench regulation!

I like to do my rough regulation on the bench, so I always take my key
leveling stick and check out the keybed - just to make sure it is pretty
planar. That way I know I can come close on the bench. I find that if the
keybed is real planar, and you have a real flat planar regulating table (not
easy to get without making sure it is planar), I can come real close to the
final regulation on the bench. If the keybed is all warped, forget the
bench - maybe forget the piano!

Terry Farrell
Piano Tuning & Service
Tampa, Florida
mfarrel2@tampabay.rr.com

----- Original Message -----
From: "Larry J Messerly" <prescottpiano@juno.com>
To: <pianotech@ptg.org>
Sent: Sunday, February 18, 2001 2:19 PM
Subject: Crown in Key Bed


> I am presently working on a Kranich and Bach that appears to have a
> one-eitghth inch crown in the key bed.  (Using a straight edge held down
> at the back of the key bed, it is 1/4 inch off the keybed at the front.)
>
> Is this the way the piano was designed or is this damage of some kind?
>
> The key frame is VERY flexible in that when it is removed, the front rail
> can easily wave in the breeze.
>
> Larry Messerly, RPT
> Prescott, AZ
>