[CAUT] Moving wippen rail

[David Love]

I have to agree with Keith here, at least as far as my overall understanding
goes.  The three leverage points are hammer flange center to knuckle contact
point on balancier (unchanged by wippen move); wippen center to capstan heal
contact point (changed, in this case improved, by shimming out wippen
flange), and key balance rail contact to capstan/wippen heal contact.  The
overall leverage is a function of those three distances.   While friction
may change depending on the degree of sliding, the balance weight, as we all
know, will not.  Occam's Razor, "one should not increase beyond what is
necessary the entities to explain anything".  

 

I go back to my original assertion and what my own experience has
demonstrated: shimming the wippen flange is just as effective as moving the
stack and unless there are other compelling reasons to move the stack, as
Jon cited in a previous post, I would recommend this as a more expeditious
method of gaining a slight mechanical advantage.  Whether it creates a
problem with jack alignment is something that once should consider prior to
such an undertaking.  Personally, I've found that there is some leeway in
this area.     

 

 

David Love
davidlovepianos at comcast.net
www.davidlovepianos.com 

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Keith
Roberts
Sent: Thursday, October 25, 2007 4:02 AM
To: College and University Technicians
Subject: Re: [CAUT] Moving wippen rail

 

The reason I disagree with the premise below is simple. We are looking at
the wippen as a separate unit but we measure the change in output of the
wippen as a function of the the entire action. Yes, the wippen power will
increase as the jack approaches the line tangent to the RA but you are
losing power at the other end as the force vector there diverges away from
the tangent line of the shank EA. Therefore the change in jack position has
absolutly NO effect on the resulant force. <GRIN> of course it has some but
as you will see it doesn't change proportionally to the output of the system
but changing the ratio of the wippen EA certainly does and is fairly
accurately reflected by the drop in DW. 

Friction, HA! measure the friction and tell me there is a change.

 

Keith

 


 



So... really  I have to go with Jon here.  The change in apparent
leverage is because of vector alignment. One also will experience a 
change in friction.

Cheers
RicB

   I shimmed a rail out today and yes, the UW & DW dropped. I don't
   attribute it to
   improving wippen ratio but vector alignment.  If I kept moving the 
   rail back
   I'm sure the numbers would degrade.
   --

   Regards,

   Jon Page

   LET'S GO RED SOX

 

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