Sustain pedal lift ratio

[RicB]

Ron

Thanks for a refreshingly technical contribution in the midst of the 
yearly pre-holiday season collage of mix-mush.  Grin....with jokes about 
triangular wheels being tossed around here on pianotech and a soon 40 
post thread about Gorilla Glue on Caut one has to wonder about the 
general level of sanity amoungst our midsts as it were.

Seriously tho... I'd like to hear more about how you go about designing 
a change in the lever systems.  I remember my brother Joe doing this to 
accommodate pianodisk systems... tho I dont think he was concerned 
directly with the lifting ratio... more a matter of making everything fit. 

Still.. this might be a nice addition to ones technical toolbox as it 
were....

Cheers
RicB


    Hi all,

    At various times over the years this topic has been discussed on the
    list. To recap some of my past contributions on this topic, the ratio
    range which seems to satisfy most pianists is somewhere in the range
    of 2.5 - 3.5:1. That is, when the sustain pedal travels 2.5 - 3.5 mm
    for every 1 mm of damper lift.

    The 1975 Baldwin SD-10 we rebuilt had an original lift ratio of
    2.0:1. A Yamaha C3 I measured at the time had 2.5:1. While a Grotrian
    275 concert grand had around 5.0:1. When we rebuilt the Grotrian, and
    the Baldwin for the first time, we had complaints about the damper
    lift of both pianos. The Grotrian was deemed too hard to control
    while the complaint of the Baldwin was that the dampers were too
    noisy when the damper pedal was released. We changed the leverage
    ratio of both pianos to 2.5:1 and haven't had a complaint since.

    My reason for sending this post today is that yesterday I tuned the
    Grotrian for a recording session, and while there, I got out the
    digital to show how we changed the Grotrian's damper lift ratio. Some
    on the list had expressed an interest in seeing the detail of this
    conversion, but from memory I hadn't gotten around to taking an
    image. Here's the image



    I've greyscaled it to take up less space.

    The original lift lever was a single piece straight lever. You can
    see where the hinge was located just behind the bass-side lyre
    support strut.

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