Sustain pedal lift ratio

[Marcel Carey]

Ron,
 
Thank you for this very informative post. I appreciate the fact that you
took the time to educate us all. This is something that is often not
done right from the start and it does improve the playing a lot.
 
Thanks again,
 
Marcel Carey, RPT
Sherbrooke, QC

-----Message d'origine-----
De : pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] De la
part de Ron Overs
Envoyé : 11 novembre 2006 02:04
À : Pianotech List
Objet : Re: Sustain pedal lift ratio


 

The pedal/damper lift ratio is calculated using the following formula.

(A/B) X (C/D) X (E/F)

For many damper systems, the push rod will come through the keybed to
contact the damper tray almost directly under the damper wire flange. In
these instances you can disregard the lever lengths F and E, giving them
a value of 1. There will be some small variation in the actual ratio due
to variations in the lever angles from piano to piano. However, the
variation is too small to worry about in practice with respect to the
ratio, but the lever angles are critical with regard to friction.

If the push rod is fitted with guide pins the angle of the push rod,
with respect to the damper tray and damper lever, won't be of much
consequence, since it will contribute very little friction. The damper
lever under the keybed is a different matter. I prefer to set this lever
so that it is horizontal at half damper lift. This arrangement will
minimise friction between the lever and the lyre push rod. For our own
225 piano, we machine away the lower-half of the damper lever thickness
where it meets the push-rod capstan, and lengthen the lyre push-rod so
that the lever is horizontal at half damper lift. This results in less
friction and less likelihood of squeaks developing between the lyre
push-rod capstan and the lever bearing-felt.

I hope you have found the above mini-doc to be useful, since this is the
first time I've written-up the procedure onto something more substantial
than a piece of scrap of paper around the workshop. However, its been
good for me to document the procedure.

For those of you who would like to know how I produced the graphic and
imported it into the Eudora programme, here is the procedure.

1) Draw the graphic using my old 2D CAD programme.
2) Capture a screen image of the drawing and save it to the desktop as a
TIFF file.
3) Open the TIFF file in Photoshop, resample, reduce in size and save as
a jpg file.
4) Drag the jpg file into the Eudora email document.

Ron O.
-- 
OVERS PIANOS - SYDNEY
   Grand Piano Manufacturers
_______________________

Web http://overspianos.com.au
mailto:ron at overspianos.com.au
_______________________

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