THUD

[John D. Chapman]

David,
I tried juicing, tried needling.  No luck.
John

On Sat, 2 Dec 2000, David
Ilvedson, RPT wrote:

> I think I would try some juice to beef up the tone.  
> 
> David I.
> 
> -----Original Message-----
> From: John D. Chapman <chapmajd@wfu.edu>
> To: caut@ptg.org <caut@ptg.org>
> Date: Saturday, December 02, 2000 5:38 PM
> Subject: Re: THUD
> 
> 
> >Remember THUD?
> >Here is the history.  I had not seen this piano until last month.
> >While tuning I noticed that notes 50, 51, 52, and 53 (top four notes in
> >agraff section,  just below the treble break) had an unpleasant
> >knock/slap sound, the same percussive knock which is in the background of
> >all piano tone, but in notes 50-53 it dominates the tone.  These are the
> >four notes between A440 and the treble break.  The orchestra conductor
> >asked me if I had noticed those four notes, as did the pianist, so I knew
> >it wasn't just my imagination. I have checked it out both upstage and back
> >stage (wood floors), and back at the dealership (concrete floor).
> >        Here is what we have done so far:
> >1.  checked hammers for loose glue joint, flange pinning, and screw
> >tightness,
> >2.  visually checked the action frame joints between notes #53 & #54,
> >3.  checked the wippens for sufficient felt at the front to keep the
> >jack from slamming into the rep lever,
> >4.  checked key frame bedding, front, back, and glides, with and without
> >damper pedal, and with and without shift pedal,
> >5.  pressed down the back key frame with a long screwdriver to see if it
> >was slapping up against the dag,
> >6.  played notes with dampers held all the way up by hand and by pedal,
> >7.  moved the action in and out to see if the tone improved,
> >8.  switched some hammers from the octave below to see if it could be the
> >hammers,
> >9.  switched some whippins from the octave below to see if it coulb be the
> >whippins,
> >10.  seated the strings,
> >11.  applied firm pressure on the bridge cap at the end of the section to
> >see if there was a loose glue joint between cap and bridge body,
> >12.  checked for clearance between the bridge and the plate,
> >13.  checked for loose ribs,
> >14.  checked for clearance between nose and bell bolts and soundboard,
> >15.  checked that the bell bolt nut which was one turn past finger tight,
> >16.  checked for foreign object lodged between soundboard and frame, and
> >between soundboard and plate,
> >17.  tightened the end screws of the diagonal plate bar, which could be
> >turned another half turn to snug,
> >18.  checked key leads and underlever leads,
> >19.  checked the key bed with a straightedge front to back.  I found that
> >the board just beyond the board on which the balance rail glides rest was
> >high.  Chalked it where it passes under the front to back board of the key
> >frame which is just under notes 50-53 and found that is was just barely
> >touching. Sanded key frame there until there was adequate clearance.
> >Playing the note by pushing up on the whippin from underneath with my 
> >finger without moving the key still produces the THUD, so I guess that 
> >eliminates the keyframe anyway.  
> >
> >None of this has changed the THUD.  
> >What have I missed?  
> >Why these four consecutive notes  with no sign of the problem above or
> >below them? 
> >
> >John Chapman RPT
> >Wake Forest University
> >Winston-Salem NC
> >
> >
> 
>