[pianotech] Upright Key Weighting

[David Stanwood]

<snip>
>The mass of the hammers comes into play much more at fortissimo, where the
>perceived force is increased, since F = ma. The faster acceleration of the
>key/hammer system is felt in the fingers of the player. If you have
>low-mass hammers, you feel like you are falling into the piano.

John, I agree that hammer mass could be an issue.  Quite often 
uprights have extremely light hammers eventhough string scaling and 
soundboard size can be quite like grands.  Adding shank clips could 
help a lot in producing a grander feel.

<snip> when you look at the 1:5 mechanical
>disadvantage with 3/8" key dip and a 1-7/8" hammer travel. A 9-gram hammer
>will feel like 45. The hammer mass gives you a dynamic downweight feel.

This formula for mechanical ratio is also mentioned in Braid White 
and it doesn't account for aftertouch distance in which key movement 
doesn't move the hammer.

David Stanwood

>So, if you want the piano to feel more like a 52-gram-downweight grand,
>look at the hammer mass.
>
>John Ashcraft, RPT
>Portland, OR Chapter