Wippen support springs and action geometry

[David M. Porritt]

David:

The average weight of a wippen when supported by the flange is about 18
grams.  Would it not be feasible to adjust the wippen springs (with the
hammers up and out of the way) so that the wippen weight is just
neutralized (suspended)?  

dave

_______________________________________
David M. Porritt, RPT
Meadows School of the Arts
Southern Methodist University
Dallas, TX 75275
______________________________________

----------
> From: David C. Stanwood <Stanwood@tiac.net>
> To: pianotech@ptg.org
> Subject: Re: Wippen support springs and action geometry
> Date: Thursday, March 12, 1998 12:11 AM
> 
> Chris writes:
> 
> >In your opinion, am I barking up the right tree with these turbo wips?
> >Will I need to change the key weight?  Will I have problems with
bubbling
> >hammers?
> 
> >Thanks for our help.
> 
> >chris
> 
> Dear Chris,
> 
> The bubbling I think your refferring to is the sort of bouncy key?  When
> the key comes up it bounces and bubbles as it comes to rest?  We've found
> that this occurs when springs are asked to do too much work.  We set up
> actions so that springs work 25 grams off the touchweight at most, Tops!
> Many actions are found with springs that are working as much as 40 grams
> off the touch. That's too much!   I've found this on pianos from Samick
to
> Bluthner.
> 
> To measure how hard a spring is working just measure upweight with the
> spring disengaged.  Now engage the spring and measure upweight again. 
The
> difference is haow hard the spring is working.  When upweight rises by 15
> grams, then balance weight and downweight will also rise by 15 grams. 
(The
> difference between up and down will remain the same because friction
> doesn't change.)   Take the time to do this metrologic study on a piano
> that you take care of.  The infromation is useful and may lead you to
ways
> to improve the action by improving uniformity of the proportion of
balance
> between the spring and key leads.
> 
> The turbo wip I measured on the model at the CA State conference was
> working 17 grams and they had study which states what happens to up down
> with spring on and off and 17 seemed to be the number that Renner was
> speaking alot.  Any comments Loyd?  Oviously the one with the spring had
> fewer leads.  17 grams is a good medium tension for wip suuport springs.
> Don't assume that they are adjusted accurately "Out of the box".  The
only
> way to tell is to measure the touch then hook up the spring and remeasure
> the touch.  
> 
> The balance weight of the keys (Balance weight is the average of up and
> down wt) should be even with the spring disengaged and when engaged.  The
> best way to treat springs is to balance the keys with the springs
> disengaged then hook them up and adjust to final balance.  The biggest
> mistake people make is to hook up the springs without accounting for how
> tight or loose the spring tension is, then balancing the keys and making
up
> for variations in spring tension with key leads, thereby making for
> inertial discontinuity and uneven front key weights.  In other words
> measure up and down wt with the springs off and check the balance of each
> key as the average of up and down (Balance Weight).  If it's not even
then
> adjust the key leads to make it even.  The only way to tell is to
measure,
> so you have to commit to the value of taking the time to measure and
> analyze the data.
> 
> There are other ways to adjust the feel of the action as well as the
sound.
>  The hammer weight which may be measured on the shank as Strike Weight.
> The action ratio which may be assessed by looking at the strike weight
> ratio.  PTG Journal June 1996 "The New Touchweight Metrology".  I'm not
> blowing my horn so much as I am inviting all of you to learn how to take
> advantage of newly available ways of looking at our work.  
> 
> Touch weight is made up of components.  Look at the components.  Hammer
> weight and action ratio make a foundation that will not be rocked by any
> spring.  Springs only allow you to balance the action with less lead than
> would be otherwise needed,... that's it!  There is advantage to using
them
> in all cases but they should be used with a full understanding of their
> specific effects.  I'm all for them!
> 
> I hope this answers your questions and sparks some new ones.
> 
> 
> David  C. Stanwood
> 
> http://www.tiac.net/users/stanwood
> 
> >Hi David,
> >
> >I caught your post and am very interested in what you had to say about
the
> >turbo wips.  I have a faculty member whom I believe would really like
the
> >feel of these.  She likes a very quick and light action with as little
bump
> >from let off as possible.  What she calls a "European feel".  (She has a
> >Bechstein at home.)  She also, however, desires the ability to play
very,
> 
> >very softly.  I have to have let off and back check as close as
possible.
> >In your opinion, am I barking up the right tree with these turbo wips?
> >Will I need to change the key weight?  Will I have problems with
bubbling
> >hammers?
> >
> >Thanks for your help.
> >
> >chris