Squeaky Sustain

[Michael Spalding]

Hi Mark,

Paul raises good points:  in particular, that the noise is due to side
pressure.  There is side pressure whenever there is mis-alignment between
the pitman (rod), the trap lever, and the lift tray.  And there will always
be misalignment because the trap lever and the lift tray are pivoting. 
Sometimes the stars and planets align, and the side pressure is little
enough that lubrication can keep it quiet.  Sometimes they don't, and no
amount of lubrication, polishing, re-bushing, etc. can make the noise go
away.  Bad design, must be corrected.  I've seen many different variations
on the solution, but most of them involve enlarging the hole in the keybed,
and tieing the ends of the pitman to the trap lever and lift tray using
either sockets in the lever and tray the diameter of the pitman, or bridge
pins in the pitman fitting into holes through the lever and tray.  Caution:
Tieing the pitman to the lever and tray at the existing points of contact
perpetuates the misalignment, putting side forces on the lever pivots. 
Establish new contact points that keep the pitmant square to the lever. 
Otherwise, eventual wear and noise.  DAMHIK.

Mike


> [Original Message]
> From: Paul McCloud <pmc033@earthlink.net>
> To: Pianotech <pianotech@ptg.org>
> Date: 10/25/2005 8:11:02 AM
> Subject: RE: Squeaky Sustain
>
> Hi, Mark.  I usually use the Protek vaseline MPL-1 on the rod.  I'd be
> cautious about drilling larger holes, because you don't want the rod just
> flopping around.  It is making that sound because there's side pressure
> there, and it needs to hold the rod in position to push on the trap
lever. 
> Lubing the rod seems to work, but how long it will last I don't know. 
I'll
> be curious to hear other's responses.
>
> Paul McCloud
> San Diego
>
>
> > [Original Message]
> > From: <mps@usol.com>
> > To: <pianotech@ptg.org>
> > Date: 10/25/2005 5:40:34 AM
> > Subject: Squeaky Sustain
> >
> > I am working on a Horugel 6' Grand.
> > The sustain pedal is very squeaky and I have traced the noise to be 
> > coming from where the push rod rubs against the wood as it goes 
> > into the hole on the underside of the piano and then up to the action 
> > itself.
> > Is there a certain lubricant that works best here or would you drill
that 
> > hole larger in diameter to remove the point of contact?
> >
> >
> > Thank you
> >
> >
> > Mark Montbriand
> > Mark's Piano
> > Service
> >
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>
>
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