There are two components to a keyboard's Touch Weight: the
Down Weight (DW) and the Up Weight (UW).

From these Balance Weight (BW) and Friction (F) are derived.
Hammer Strike Weight is also important, not so much on a vertical
but certainly for grands.

Knowing their relationship and how to measure them are understood
by only a few people. You can delve into this science with an
Internet search of David Stanwood.

Jon Page
Harwich Port, Cape Cod, Massachusetts
https://pianocapecod.com/