[CAUT] Moving the Wippen Rail.

[Keith Roberts]

I agree completely with you. It's amazing how many of the wippen rails are
not in the right position and then not getting exact replacement parts or
changing bore distance, or knuckle placement  or size of knukles, can mean
that a rail that was in the right spot needs to be moved. Usually the
knuckles are moving in the direction that you can shim the rail to match.
There are so many subtle differences between actions you need to be very
careful.

Let off will take up more of the key stroke and the drop screw will not be
so high.

Thanks Jim


On 11/3/07, James Ellis <claviers at nxs.net> wrote:
>
> I have been reading the mail re moving the wippen rail back to change the
> action geometry to lighten the touch.  It was not my intention to get
> involved in this discussion, but I see that confusion persists, and I
> would
> like to help sort it out, if possible.  I don't remember exactly who said
> what, and it doesn't matter.  Argument is not my objective.
>
> Moving the wippen rail back increases the distance from wippen center to
> capstan contact.  It also decreases the distance between capstan contact
> point and jack center.  If the jack were perpendicular to the wippen, and
> if the hammer shank were perpendicular to the jack and parallel to the
> wippen, the very slight change in the angle of the jack would be
> irrelevant, and the ratio change would simply be that caused by the ratio
> change of the wippen.
>
> But that's not quite the way it is.  The jack is at an algle to the
> wippen,
> but perpendicular to the hammer shank.  When the jack is realigned to the
> knuckle after the rail has been moved back, its angle to the wippen will
> be
> changed.  If we are going to be exact about this, we will have to figure
> the cosine of that angle in each case, and subtract one form the other to
> find out how much the change in jack angle actually makes to the leverage.
> We will find that it is some, but not much compared with the simple change
> in wippen leverage.  Another way of looking at it is to compare the
> distance from wippen center to capstan contact against the distance from
> wippen center to jack contact with the knuckle.  I think this is what Ric
> B. is talking about, but I'm not sure, and I don't want to misquote
> someone.  That's a good approximation, but it's not accurate either,
> because an imaginary line drawn from hammer center to wippen center does
> not intersect the jack/knuckle contact point.
>
> If we are going to be really fussy and exact about this, we will have to
> solve for a bunch of angles and lever arms to know just how much
> difference
> it does make.
>
> However, something more inportant is being overlooked here.  If the wippen
> rail is moved back, and the jack realigned to the knuckle, the jack's
> clearance at the front of the balancier window is going to be reduced.  If
> it is critical to begin with, and it should be for maximum repetition,
> then
> the new position will cause the jack to hit the window cushion hard on a
> hard blow, perhaps breaking off the tender.
>
> There have been a few times when I have moved a wippen rail, but those
> were
> only after careful measurements told me it was in the wrong place to begin
> with.  I have never done it merely to change action geometry.
>
> Sincerely, Jim Ellis
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/caut.php/attachments/20071103/05ad2bf0/attachment.html