advice on action parts

[Kenneth Sloane]

        Reply to:   RE>advice on action parts

Don't get stressed out over touch weight as measured with calibrated weights on the keys. I have seen many actions with "appropriate" upweight/downweight relationships that pianists perceive as heavy. In such an action, you can assume friction is not the problem because excessive friction will increase downweights while decreasing upweights, giving you an action that can be weighted to have a traditional downweight (around 50 grams) but no where near enough upweight to make it work (you should have around 20 grams or more).

The problem in such an action is the existence of too much inertia which is caused by either parts that are too heavy or levers in the action that do not provide enough mechanical advantage. In regard to the former, the hammer is the greatest contributor to inertia because it has to be accelerated over the longest distance and is a heavy action component. In regard to the latter, hammer shank action center to knuckle distance and key ratio are especially important.

I have seen actions that, even with relatively light hammers, cannot be weighted in any way in order to feel light. These are usually Steinways with shanks of the pre 1984 dimension (15.5mm action center to knuckle distance) that also have key ratios significantly less than 2 to 1 (as you get below 1.9 to 1, inertia seems to become a problem). Fortunately, installing post 1984 dimension shanks with their 17mm action center to knuckle distance will frequently alleviate the problem, even if the key ratio is not ideal.

However, this is less true for nine foot pianos with their longer keys because the longer key provides additional wood that introduces more inertia. This was proven rather dramatically to me with a "D" here at Oberlin that was built in 1987, had post 1984 shanks (17mm action center to knuckle distance), good upweight/downweight specs, and was always perceived as being heavy. At this moment, I can't find my notes on that piano that would tell me what the key ratio average was; but, suffice to say, that it was significantly below 2 to 1.

By moving the capstans to get a better key ratio -- you also have to move the wippen heel to match the new capstan position -- the piano suddenly felt light, so much so that I wished I had not moved the capstans so much. Nothing else was changed other than the capstan and wippen heel position (the latter gives the wippen more mechanical advantage also) and now people were saying the piano was a little on the light side.

Ken Sloane, Oberlin Conservatory


--------------------------------------
Date: 3/20/99 7.47 AM
To: Kenneth Sloane
From: caut@ptg.org
I need some advice. I was asked yesterday to rebuild the action on an
old Steinway XR (M size player-player removed). The touch is already
heavy (58-60 grams) with the original parts, so I need to use new parts
that will not add any extra touch weight to the action. Should I go with
all original Steinway parts, although I've had weight problems with them
before on a piano, or go with aftermarket parts using the newer light
hammers Pianotek has advertised. I'm certainly no expert at this, so any
advice would be most welcome.
Dave Forman
Westminster Choir College of Rider University


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