lowering inertia without voiding warranty?

[Bob Tate]

HI all.
this is my 1st post here. I haven't been around the Guild for 30 years--I think it's time to come  back : ).I

this question in particular, concerns my own piano, an Estonia 190.

It's a sweet piano. I went through many, before finding this one. It's really an exceptional piano, except when playing at speed, it's a tank. --I'm working on a piece that has arpeggiated 16ths, with the quarter at 144. That's darn fast.  And with an injured wrist, even harder.

So, how to overcome the high inertia/heavy touchweight?

I'm working with 2 highly regarded techs, who do David Standwood's method--but we are at somewhat of a loss as to what is the best approach or if there even is one.

The FW is high, except for the top treble, where it goes to low or lower.
The up/dwn weight of the keys are pretty close, but need to  be smoothed--especially the up--it's enough to sometimes actually knock my fingers off the returning keys.

The AR, shows the inertia.   I'm (we) are looking at >6.2. I would like it around 5.5, and lower the FW into the low to medium range.

We've figured out that the key geometry is in trouble. But to move the capstan or knuckle, will void the piano's warranty.

The action is German Renner, with German Renner Blues. 

The supposedly "correct" solution is to lower the hammer weight. However, since the hammers are already light, I'm certain that'd kill the voice of the piano--and Renner says that's not good to do to their hammers.  Besides, we don't think we can take off enough on the hammers to get the AR down to the 5.5 goal.

The back of the wippens have an extra bit of wood with holes for a pin. It looks like wippen helper springs would go there. We thought that might give us a good start at lowering the inertia--I tell you  (144x4), that's 576 notes/min tires your out very quickly at high inertia. 

I called Renner USA & while they have the springs, they have nothing else and no instructions as to what else is needed to install them.  I guess it's a case of Renner USA vs Renner Germany.  And Tokiwa doesn't seem to make anything that will work.

So I can't find any helper spr.ings to even try.  I understand they are a real pain to adjust, but since it's my piano, I can spend the time to get the right.

Bob at Pianotek was helpful.  He suggest adding 1/2 punching to the key at the balance rail. My puncings are scarlet (.055). Not having any, I used several layers of maksing tape to get up to about .033, in the shape of a regular puncing, cut in two, and stuck them on --facing the right way-- at the balance pin hole of the key.

This indeed did lighten the feel of the piano, but it caused it to be sluggish. Plus it raised the key height 1/16 and the back end, nearly 3/8" (which makes since with the leverage as we calculated is above that 6.2 to 1.

To get the hammers back down to an acceptable blow distance, I lowered the capstan, which raised the keys fronts even more. Now I'm in dip trouble.

So that's where it stands .

It comes back to lightening the hammers? (but they are already light and would loose too much felt + probably wind up with the thinnest tails there could ever be). The keys have lots of lead in them--but the DW is about 50-52.. 

Am I stuck to not being able to play at speed--no Chopin or Schubert. What else can we try?  --no wippen helpers, at least I can't find any. And changing the location of the capstan, knuckle, will kill the warranty.

I'll be pulling off the masking tape today, to get the dip and hammer blow back to where it should be.  I'm back to ground zero.

Bob, Provo UT










      
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