[pianotech] Fw:solution was key ends and damper timing

[Gene Nelson]

>
>> sharps travel more than naturals.
>
> Sounds like poor action/key geometry.
***Indeed. This is my 5th back action. The 4 previous never had an issue 
like this at the key ends.


>> The key length increases about 8mm from note #1 through #65.

*** Sorry, this was mis-stated - key length decreases from #1 through #65. 
Actually the key length decreases evenly from #1 through #88 by 10mm.

> I had to re-read this a time or two before I realized that the capstans 
> are probably in a straight line, parallel to the balance point, and the 
> additional key length is only beyond the back check, to reach the tapered 
> line of the damper underlevers, presumable maintaining the same key length 
> from 66 to 88, because there were no dampers involved.  Are my assumptions 
> correct?

*** Balance rail, hammer rail, whippen rail, back rail and key capstan line 
are paralell (had to slightly alter key capstan line) front rail tapers with 
the keys.

>> After I build the back action it is my sincere hope that this is really a 
>> solution and the new damper timing will feel and look even.
>
> Sounds like you found the same "work-around" as the manufacturer did. My 
> greater concern would be what does the significant difference in natural 
> and sharp key ratios do to the action performance and regulation.  Too 
> much aftertouch in the sharps?  More key leads in the sharps than 
> naturals?  Significant inertial differences that make the sharp keys feel 
> heavier than they really are, relative to the naturals?

Regarding regulation I have a really good hammer line with consistent key 
dip. Key height is slightly higher in the bass by 1mm.
Regarding touch I have not got that far yet but the sample keys (naturals 
only) suggest a light fast action. I have been able to remove some key leads 
and the down up weights are low 50's low 30's.
This action has a very low ratio with 11mm dip and 44mm blow. Aftertouch is 
about half of drop and I set it very close. The sharps regulate the same as 
the naturals.
Gene
>
> Frank Emerson