the importance of action frame rigidity

https://skydrive.live.com/redir.aspx?ci...ALmzXIN03U

in the above video, I demonstrate the discovery for me of the necessity of a firmly fixed, rigidly aligned and structurally sound action frame. It seems that very few keyboard manufacturers use iron frames in their boards, although some have done, CME UF8 for example. But since iron is an essential structural component of a physical piano, why should  the use of one of the most rigid materials be sacrificed for mere portabilty (or fashion). And I'm sure the UF8 was somewhat more prtable than some of the bohemoths that have been (or are being) produced without the use of iron for the purpose of a stable and consistent action! You'll find that fixed digital pianos with their cabinetry often exhibit a more consistent action for this very reason, that their actions are so much less prone to the twisting and bending as a portable keyboard's because of the effective extra support of the digital piano's body structure.

Twisting or bending in any action frame will cause problems that will effect some keys more than others. This will directly effect the consistency of the whole range and produce inconsitent velocities, whether yhat be in a traditional physical piano, or a digital piano. Admittedly, with a digital piano, compensation can be made via software adjustments, but, as I have discovered after such a long time working on the Nero NUMA / PNOscan project, this is definately no compensation for the physical inconsistencies of a bent or twisted action frame/structure often found to be the cause of such velocity inconsistencies.

The demonstration video above shows what happens when I push the front and back rails of the TP40 WOOD action frame together. The point at which the keys are level corresponds to the point at which I am unable to compress front and rear rails further. Tonight I intend to fix the front and rear rails at this point and shall then test the keys to assess performance and consistency of the above demonstrated keys. I will report my findings soon.

Warm Regards,

Chris