[CAUT] Lighter Touchweight

[Keith Roberts]

I disagree that the advantage is taken away at the Knuckle. The jack center
pin is the end of the resistance arm of the wippen, not the knuckle. I can
stand a stick on the end of a lever and without moving the bottom, lean the
stick forwards and backwards and up to a certain point there will be no
noticeable change in the upwards force at the tip of the stick. The
jack acts the same way.
If you set the jack so it is centered under the knuckle or the front edge is
lined up with the core, does it make any difference to the measured output
of the system?

Keith Roberts


On 10/20/07, Jon Page <jonpage at comcast.net> wrote:
>
>  Not sure I understand what you mean here.  Putting aside the jack knuckle
>
> interface angle, why would the advantage of shimming out the wippen be
> lost
>
> at the knuckle?
>
>
>
> Because the knuckle is moved further out on the repetition lever also.
> Moving the rail back, increases the distance from the center pin to the
> capstan on the wippen support (+)  but it also increases the distance
> from the cp to the knuckle (-). It's a wash.
>
>
> Moving the stack alters only the input dimension on the wip ratio.
>
>
> In Barbars's case, moving the stack forwards increases the wippen's ratio
> and it will regulate with a longer blow distance but will also increase
> touchweight and friction.
>
>
> In the Baldwin grand case, moving the stack back will lower the wippen's
> ratio and
> will lower the touchweight and friction.
>
>
> Touchweight and FW have to be taken into consideration as well as the
> amount
> of room to move the keyframe fore or aft between the fallboard and keyslip
> because
> if one moves the stack, the keyframe needs to be relocated to maintain
> strike point.
>
>
> I'm doing this right now on a Samick. Done it many times with success
> because the stack
> isn't always in the right spot to begin with. Even treble to bass
> positioning of the capstan
> on the cushion. I find it's usually tha the capstan is further back on the
> cushion than the treble causing the wippen ratio to be uneven across the
> compass.
>
>
>
> Moving the wippen rail is only to align the centers. There is no leverage
> gain
>
> as one might think by moving the rail back because the advantage you gain
>
> in regards to the capstan is lost at the knuckle. Whereas moving the stack
>
> back increases the input dimension without increasing the output
>
> thereby lowering the ratio.
>
> --
>
>
> Regards,
>
> Jon Page
>
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