Crown in Key Bed

[Larry J Messerly]

I have just checked, and the "hump" is consistant from bass to treble.  

Larry Messerly, RPT
Prescott,AZ

> 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
> >
>