Adjusting wippen assist springs

[Phillip Ford]

> >To those of you who use wippens with assist springs,
> >
> >1.  Do you adjust them so that they are giving the same assist on every
>key?  In other words so that  WW (wippen weight) is the same for every key?
>  Or do you adjust them so that the assist is tapering from more in the bass
>to less (or none) in the treble?
> >
> >2.  In my opinion, actions with strong spring assist don't feel 'normal'.
>What do you think is the limit of spring assist at which the action might
>still have a normal feel?
> >
> >3.  How you measure the amount of assist that you're getting?
> >
> >Phil Ford
>
>Hi Phil,
>
>I'll answer your questions in reverse order...  The easiest way to measure
>the amount of assist is to measure up weight then disengage the spring and
>remeasure up weight again.  You can use down weight if you prefer.  Up and
>Down Wt will both rise by the same amout when the spring is disengaged.
>(springs don't effect the friction significantly)  For instance: if you
>have a key that is 20/50 and with the spring off is 28/58 then the spring
>is working 8 grams.

That seems like a straightforward approach.  My original thought was to 
determine what WW I wanted with the spring assist and then measure that 
directly for each wippen and adjust the spring to give the desired 
number.  I thought that this would be more accurate.


>As a general rule it's safe to work the springs so that they just support
>the weigh of the wippen.  This would take about 9-11 grams off the touch
>weight.  17 grams is generally considered the upper limit to working
>springs without significant risk of comprimising normal feel.  Some
>pianists are more sensitive to the effect than others.

Thanks.  I was hoping for a number.  So, that is 17 grams of spring assist 
at the capstan?

On the particular action that I'm working on (old Hamburg Steinway) I 
measured the angle of the wippen at key rest and also at full keystroke.  I 
then measured WW at these two angles.  It varied significantly, or in other 
words, the spring assist varied significantly.  With the springs working in 
the general ballpark of where I thought I was planning to use them I 
noticed a change of 14 g in WW from rest position to full keystroke (an 
increase of 14 g of WW when going to the full keystroke position from rest 
position).  Have you observed this yourself?  If you set the spring for
17 g assist at rest then you would only be getting 3 g assist at full 
keystroke.  This isn't much assist.  Is that OK?

>   How much the spring
>can work depends on the diameter of the spring.  Renner makes three sizes,
>0.7mm, 0.6mm, and 0.55mm.  If you are going to work as much as 17 gram off
>the down/up wt then use the 0.7mm, for up to 12 grams use the 0.6mm, and
>for up to 6 grams use the 0.55mm spring.

Thanks.  I wasn't aware of that.  I just ordered a set of turbo wippens 
from Renner, but didn't specify.  I wonder what I'll get.


>Perhaps the easiest way to use wippen support springs is to adjust the
>tension of 88 springs with the stack on the bench so that it lifts the
>wippen almost to the drop screw.  This makes the WW essentially zero. Once
>the tension is even on all the springs then weigh off your keys to a normal
>down weight (assuming friction is even) or a specified balance weight.
>This is the method that Steinway Hamburg used for a time in the 20's.  If
>you end up back leading in the treble you can taper the spring tension down
>to zero in the last octave.
>
>You can also taper the spring tension from Bass to Treble with the springs
>ending at any point you want.  I prefer using 88 springs with uniform
>tension throughmost of the keys with a tapering off of tension in the last
>octave.

My original thought was to use springs on all 88 keys since that is what 
was there before.

>
>Springs should be considered as a high performance option, not a fix for
>mismatched hammer weight/ratio.
>
>David Stanwood

I normally don't use assist springs.  This is an old Hamburg Steinway O action.
It currently has assist springs which I am assuming are original.
Also somewhat low key ratio.  Someone at some point set the springs very strong
and took some of the weight out of the keys.  I am planning to put on new parts.
My intention was to use 3/4 medium to top medium hammers.  With these hammers
and current action geometry if I don't 
use assist springs then I would have to lead beyond max FW.  I'm willing to 
change the geometry, but my thinking (and at the customer's request) is to 
keep something of the original character of the action.  By using some 
moderate assist I can keep the current geometry (perhaps changing knuckle 
location slightly) and keep FW well below max.  I would also be putting 
back springs which were there to begin with.  Thanks for your comments.

Phil Ford