Bedding Blues

Jon Page jonpage@mediaone.net
Wed, 09 Feb 2000 20:05:57 -0500


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David,
You had it right the first time. A wedge driven into a kerf on one side of
a board will bow in that direction. So if the center is high, a shim placed
on the bottom will flatten it out. Actually a long tapered wedge can be
driven in the appropriate distance. A cut is made about a fourth to one
third the thickness into the rail. I have used a router with a straight bit
and
set the guides to make the taper. A long spline cut to the same taper can
be driven in to straighten it out. A few may be needed.

I think it was Yamaha which did this on grand keyframes years ago.

Kerf's up,

Jon Page

At 04:08 PM 02/09/2000 -0800, you wrote:
>Yeah, If you wedge from the bottom it forces it up...oops....
>
>David I.
>
>From:                  "Paul" <tunenbww@clear.lakes.com>
>To:                    <pianotech@ptg.org>
>Subject:               Re: Bedding Blues
>Date sent:             Wed, 9 Feb 2000 13:34:56 -0600
>Send reply to:         pianotech@ptg.org
>
>> David
>> I used this wedging technique on a warped Kawai key frame. The cut(s) was
>> made in the top of the key frame and veneer was epoxied in the kerf.
>> Keyframe bedded perfectly and to date there has been no problems with it.
>> 
>> Paul Chick
>> Plainview MN
>> ----- Original Message -----
>> From: David ilvedson <ilvey@jps.net>
>> To: <pianotech@ptg.org>
>> Sent: Wednesday, February 09, 2000 12:15 PM
>> Subject: Re: Bedding Blues
>> 
>> 
>> > Consider making a cut on the bottom rail and putting in wedge
>> > which will bow it down?
>> >
>> > David I.
>> >
>> > Date sent:      Wed, 09 Feb 2000 18:22:45 +0100
>> > From:           Richard Brekne <richardb@c2i.net>
>> > To:             "pianotech@ptg.org" <pianotech@ptg.org>
>> > Subject:        Bedding Blues
>> > Send reply to:  pianotech@ptg.org
>> >
>> > > Hi list
>> > >
>> > > Ok.. I got this Schimmel long 6 footer, and it simply wont bed right..
>> > > lots and lots of spring in the middle tenor (# 25 - 40) which causes
>> > > this unbelievable bounce in the hammers at rest while playing hard, and
>> > > causes lots of lost power.. After doing everything possible to correct
>> > > the bedding and getting nowhere I discovered that the balance rail is
>> > > way off from flush with the framwork on the keyframe.
>> > >
>> > > This particular configuration is such that the balance rail is cut out
>> > > too accommidate the cross boards of the keyframe, and they should
>> > > present a flat surface where they are joined. But at key 35 or so on
the
>> > > treble side of the crossboard the balance rail is about 0,70 mm off
>> > > (away from the keybed).
>> > >
>> > > All keyframe screws are tightened down as much as I can get them. For
>> > > the moment I simply added a 1mm front paper bushing to the area (the
>> > > balance rail is also warped upwards in the tenor section, and bends
>> > > upwards and away from the bed again from about key 50 onwards, tho
>> > > bedding screws take care of that problem)
>> > >
>> > > I am wondering what is best to do here... I could install a "sleeper"
>> > > bedding screw right in the middle of this section, or I could perhaps
>> > > plane the whole underside flat again,  or perhaps build up the
offending
>> > > part with some laminate..
>> > >
>> > > Advice boys and girls ???
>> > >
>> > > Richard Brekne
>> > > Associate PTG, N.P.T.F.
>> > > Bergen, Norway
>> > >
>> >
>> >
>> > David Ilvedson, RPT
>> > Pacifica, CA
>> > ilvey@jps.net
>> >
>> 
>> 
>
>
>David Ilvedson, RPT
>Pacifica, CA
>ilvey@jps.net
> 
Jon Page,   piano technician
Harwich Port, Cape Cod, Mass.
mailto:jonpage@mediaone.net
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