Action Ratio and Dip and Blow and Etc.

[Dean May]

I've never studied Stanwood and it causes the head to spin to try to follow
what you all are talking about. I am definitely saving these exchanges in my
archives for when I am able to study it a little closer. But it is very
interesting to me, and I have dabbled a little in adjusting touchweights.
The more you do this stuff, the more intuitive it becomes, I guess. So I
continue to try to follow the threads and immerse myself in the terminology.

 
Action spread has always one of those great mystery areas. The first guy to
train me (who it turned out knew very little about pianos) warned me to
never touch it. So for many years I considered it a big taboo, which was
probably not a bad thing. 
 
Since these things do get intuitive I know it is hard to quantify, but can
we try? We change action spread to make sure the jack is properly aligned
with the knuckle. It must be done judiciously as it also causes changes in
the action ratio, that is the amount of key movement to the amount of hammer
movement. Then there is something called magic line that I have a vague
understanding of. 
 
For an intermediate regulator such as myself, i.e., one who is not going to
make extensive geometry changes like moving capstans, knuckles or altering
heels, are there any other criteria one should consider in setting action
spread? 
 

Dean

Dean May             cell 812.239.3359 

PianoRebuilders.com   812.235.5272 

Terre Haute IN  47802

 

  _____  

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of David Love
Sent: Saturday, July 07, 2007 11:36 PM
To: 'Pianotech List'
Subject: RE: Action Ratio and Dip and Blow and Etc.



Terry:

 

Like Jon mentioned, check the regulation by sample.  A 41 BW with ½ FW max
makes me a bit nervous that the action ratio might be too low and will not
regulate without excessive key dip.  The low ratio might be a function of
the increased action spread.  I believe Renner parts (if that’s what you are
using) are designed to have a spread of 113.5 mm.  

 

My entire range of BWs is 34 to 42.  I use 34 when the customer has hand
issues and needs something very light.  With 14 grams of friction in the low
bass you will still have 20 grams of upweight.  That’s my absolute minimum.
I will go up to 42 if, for some reason, someone wants it pretty heavy and
meaty.  I have some customers who are just really big, strong muscular
pianists and that kind of weight suits them better.  Some people believe
that heavier touchweights are good for muscle devlopement (I don’t agree)
and some concert players simply don’t want to ever go to a piano that is a
surprise heavy action.  They want to be sure that their own piano is heavier
than anything they are likely to encounter.  My preference for 37 is derived
empirically.  I prefer actions just a shade on the light side.  With concert
grands I may go 38 or 39 because I might need a slightly heavier hammer and
because concert pianists have to deal with adrenaline which can make a too
light action a problem.  Under normal relaxed playing, I prefer my hands and
arms to remain completely relaxed.  A touchweight that allows for total
relaxation through the hands, wrists, forearms and upper arms and allows the
pianist to play with relaxed weight rather than muscular force produces the
best tone.     

 

High upweight is not a concern except as it relates to overall BW.  High
upweight can be a function of unusually low friction.  After actions leave
the shop the friction generally doesn't remain so low.  Your 50/32 could
very easily turn into 52/30.  I prefer a DW of 48 in the middle of the
piano.  Others may not agree.  A 37g BW which comes out 48/26 with
approximately 80% FW max would be a very player friendly action—especially
if it regulated properly.

 

Your question about “normal” lead I don’t quite understand.  Forget about
normal for a minute.  The 3-2-1-0 pattern is not necessarily “normal”.  Many
of Stanwood’s actions have a 4-3-2-1 pattern but the leads are located more
toward the balance rail.  The improvement in inertia and speed of return is
arguably worth it.  The low FW that you currently have is because the two
leads are located more toward the balance rail.  Typically, a two leaded key
in that position would have the leads in the forward position, the ones that
you removed.  If you were to decide to reduce the BW I would add one lead on
the balance rail side of the existing two leads.  A 12-13 gram lead in that
position would reduce the BW by about 4-5 grams.  There’s no reason to try
and change the BW by altering the action ratio.  It may already be too low,
it certainly isn’t too high.  Action ratios, among other things, will be a
determinant in how the action regulates.  

 

Imagine a simple lever: a teeter-totter.  With two people each weighing 100
lbs sitting on each side with the fulcrum in the middle, they will balance
each other and when they go up and down, they will travel the same distance.
Move the fulcrum toward one end so that the distance from the fulcrum to the
end is twice as long on one side as the other and the amount for force
required to lift the person on the shorter side has been reduced by
one-half.  Now it will only take a 50lb person on the long side to balance
the 100 lb person on the short side.  However, the distance the person
travels on the short side relative to the distance the person travels on the
long side will have also been reduced by one-half.  In effect, you have
reduced the BW by changing the leverage but because the distance traveled on
the short side has also changed you have, in effect, changed the regulation.
Now the person on the long side will have to travel through twice as long an
arc to get the person on the short side to travel the same distance that
they had before.  In other words, you will need more dip. 

 

That’s the trade off.  In your case, you don’t need to make that change.
Figure out with what arrangement the action will regulate properly.  Always
do that first.  Then figure out if it will balance and with what SW and FW.
If they don’t fit into your touchweight goals then either change the SW by
reducing hammer weight or settle for a slightly higher FW while still
keeping things under maximums or settle for a higher BW or some combination.


 

And Jon is also right about when it ends.  It doesn’t.  On the next action
you get to start all over.  

 

 

 

David Love

davidlovepianos at comcast.net

www.davidlovepianos.com 

 

 

-----Original Message-----

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Farrell

Sent: Saturday, July 07, 2007 2:44 AM

To: Pianotech List

Subject: Re: Action Ratio and Dip and Blow and Etc.

 

Snip


 

Seem like the only thing concerning me is my high Up Weight and Balance
Weight. Are these a real concern? Why/how would the action perform better if
I were able to get BW down to 37g (or there abouts) and reduce UW to 25g or
so - all, or course, without changing  leading, SW and DW? Seems to me the
only way to potentially do that would be changing the action ratio - but how
- capstan, wip rail, knuckle? 

 

And I still have the nagging question about key lead on this action: Why do
I have such a very low FW, yet a "normal" amount of lead? This also has me
scratching my head and worrying that something is horribly amiss elsewhere -
again, the little bit I think I know about action balancing is that
everything is a compromise - you don't get anything for free - the only way
to pay Peter is to take from Paul.

 

Man, when does it end?    :-0

 

Thanks for all the input.

 

Terry Farrell

----- Original Message ----- 

 

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