[CAUT] Lighter Touchweight

[Keith Roberts]

Yes that drawing is true if you are measureing the actual distance moved of
the the arcs but we are talking weight and force not key dip and hammer
travel. That action ratio is only good for distance. For weight or force,
the effort is applied at the wippen cushion and transmitted to the jack pin.
The jack is not a lever so the force at the top of the jack is equal to the
force at the center pin. Correct me if I'm wrong but then I think I can move
the jack back and forth at the knuckle, rotating it slightly about the
center pin, and there is no significant change in force UNLESS you get the
parts too far out of alignment.
You need to look at what you are trying to acomplish. As you can see from
the drawing that moving the wippen rail back will increase the length of the
arc produced at the jack/knuckle and also decreases the length of the arc of
the the corresponding effort arm. Therefore these two movements offset the
distance changes of the the arcs and you see almost no change of measurement
of hammer travel. Yes you are right.
However the force transmitted did change and that is what you want. A
lighter perception of the weight.

Keith Roberts



On 10/21/07, Jon Page <jonpage at comcast.net> wrote:
>
>  I'm sorry but the resistance arm of the wippen is to the jack center pin.
>
>
>
> Then YOU tell these guys that they're wrong...   (pdf attached)
>
>
> I have moved many a wippen rail and not had a minimal difference
> in touchweight or friction. But move the stack by the same amount and
> you'll notice a difference.  Moving the rail aligns the centers, moving
> the stack
> alters the Wippen Ratio. Moving the capstan alters KR and Wippen Ratio.
> So when relocating the capstans is not viable, look to the stack.
>
>
> I offered this option since we were speculating (lacking more info) on
> treatment
> of these actions.  When regulation or mass alteration does not accomplish
> your goal then look a little further.
>
>
> One sign might be shanks which are not centered over their rest cushions
> or wips
> in the bass and low tenor. Once the stack is moved (usually back) the
> realignment
> of the hammers to the strings also places the shanks more centered on the
> rest felt.
>
>
> To me it's just another overlooked aspect.
>
> --
>
>
> Regards,
>
> Jon Page
>
>
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