replacing a Bluthner action

[Avery Todd]

Thanks, Ric. I knew you'd done "something" with magnets but just couldn't 
remember
exactly what. And all my Journals are at the school. BTW, I did read the 
article. :-)

Avery

At 08:00 PM 12/29/04, you wrote:
>Avery Todd wrote:
>
>>I thought Richard did "something" along the lines of a magnetic action.
>>Am I wrong?
>>
>>Avery
>
>I have a full blown origional solution to magnetic assist actions, which 
>employs a pair of opposing magnets on the key stick and whippen forward of 
>the capstan, and a pair of attracting behind the capstan.  This is 
>different then most other assist systems in that it pits one moveing lever 
>against another instead of a non-moving point against one of the 
>levers.  The whole system is described in an article published both in the 
>American and European journals last year for those interested.
>
>That said,  the exact same concerns I have stated here were underlined in 
>that article. Assist systems should not be used to avoid dealing with 
>designing into an action desirable mass levels.... i.e. inertial 
>characteristics... i.e. dynamic touchweight.  Flip side of that 
>postulation is that once these are designed in, the only real need for any 
>assist mechansisms would be to compensate for very small variances in 
>action ratio that are unavoidble in building any action.
>Essentially, this means around 1-2 grams dead DW max, unless one is 
>designing purposefully an action which will be used to replace a 
>predetermined amount of counterbalance mass. To my knowledge, no one yet 
>has done any real research into the resulting dynamics of such an action. 
>That fact, combined with the more generalilzed fact that pianists playing 
>concert intruments around the world have clearly demonstrated a preference 
>for non assisted actions... leads me to believe replacing counterbalance 
>mass with assist springs is not such  a good idea... at least not as has 
>been employed by any manufacturer up to the present. So I conclude for the 
>time being that any assist mechanism should only be used to even out very 
>small variances in static DW.  One could argue that it would be better to 
>find the root cause of such variances (ratio problems key to key) and 
>solve those instead.
>
>fwiw... I have refined the whole concept employing a new twist on the old 
>rocker arm capstan to eliminate the problem of the magnet pair getting in 
>the way of capstan adjustments.
>
>Cheers
>RicB
>
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