Adjusting wippen assist springs

[David Love]

The method I have used is to first precalculate how much you will be using
the assist spring for.  Then set the balance weight with the springs
disconnected and chart the up and down weights for each key.  Using the
upweight as a guide, engage the spring and increase the tension until you
achieve the new target upweight for your final balance weight.   

For example, let's say you want to displace 5 grams of FW by the use of the
spring.  If you final goal is a balance weight of 37 grams, set the balance
weight with the springs disconnected at 42 grams.  Chart the up and down
weights.  Let's say that note 40 comes in with a DW of 52 grams and an UW
of 32 grams (52 + 32 = 84, divided by 2 yields a BW of 42 grams).  Engage
the spring and increase the tension until you get an UW of 27 grams.   You
can double check the DW if you want, but it is not really necessary
assuming you've measured accurately and the action has not gone through
some humidity swing that might effect the friction.

BTW, when I do use assist springs (which is not very often) I aim for
uniform application throughout the keyboard.  However, I try to avoid
excessive back leading (weights on the backside of the balance rail.  I
will therefore accept if the upper end of the piano might not need assist
springs.  But if it does, I go ahead and buy the kit and add the springs to
the wippens that don't have them.  

David Love
davidlovepianos@earthlink.net


> [Original Message]
> From: Phillip Ford <fordpiano@earthlink.net>
> To: <pianotech@ptg.org>
> Date: 12/11/2003 12:39:41 PM
> Subject: Re: Adjusting wippen assist springs
>
> >Hi Phil,
> >
> >I just finished a rebuild with so-called "turbo" springs. The main thing
> >to shoot for is touch weight which is graduated from bass to treble.
>
> Maybe.  What do you mean by touch weight?  Down weight?  Some people
think 
> that down weight should be the same for every key.  Others think it
should 
> be graduated from bass to treble.  Certainly the key front weight should
be 
> graduated from bass to treble.  But you can achieve this with wippens
which 
> are all the same WW or with wippens with WW graduating from bass to 
> treble.  I was wondering what people chose to do in this regard and why.
>
>
> >First reduce the spring tension so that the hammer falls back positively
> >on the wippen. Some springs are so strong that the hammer will rise and
> >stay up after checking.
> >
> >Rough regulate the action, and then reduce the spring tension further to
> >your desired up and down weights. If your experience is like mine, you'll
> >find yourself bending the springs so much that they hardly support the
> >nylon cords they hook into.
>
> On my initial experiments with attempting to figure out how much spring 
> assist I was going to use I certainly reduced the spring strength 
> significantly from where it was out of the box on the new whip.
>
>
> >There's a lengthy article on wippen support springs on the RennerUSA web
> >page by Chris Robinson. You might want to read it. He even suggest
> >removing key weights and letting the springs determine the touch weight.
> >
> >Charles Faulk
>
> Thanks, I'll check it out.
>
> Phil Ford
>
>
>
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