[CAUT] Moving the Wippen Rail.

[Richard Brekne]

Hi Jim

This is exactly what my origional response was. And I think comparing 
your off list note to this one you meant to use the word leverage 
instead of geometry in your last sentence.

Moving the whippen rail enough to get any significant change in ratio 
when it is geometrically in the right place to begin with will cause 
other problems.

For clarification about the jack angle.  It turns out that it boiled 
down to being a question of whether the support of an extension arm or 
the position of the contact point for load of the extension arm was the 
appropriate place to measure leverage.

As I understand it, using torque to describe the lever,  the effective 
arm length is figured by drawing using the fulcrum and the length(and 
angle) of the force vector of the load as the hypotenuse. The effective 
arm length then is the resultant opposite side.  Alternatively you could 
think like I have and think in terms of how far out on the lever the 
normal (a perpendicular line drawn from the lever itself) up to this 
point is, and figure your trig the opposite way. I'll draw a pic of this 
and post it to make it clear this evening.  Essentially this is the 
perspective used when one says the length of the lever arm on a key is 
directly below the contact point of the capstan.  Thats not entirely 
true unless the lever is perfectly horizontal.  Like I say... I'll draw 
a pic tonite.

Trig games are always fun !

Cheers
RicB



    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