Action Ratio and Dip and Blow and Etc.

[David Love]

I meant a 9 gram hammer weight.  Strike weight would be plus the shank.  At
note 1 I am generally in the 9 - 9.5 grams hammer weight.  Add 1.8 grams to
get the strike weight on average with a Renner shank.  Your 10 gram hammer
producing a 11.9 SW at note 16 is easily a full gram higher than I would
normally go.  I don't use the smart chart, btw, I use what the set wants to
give me.  If the curve deviates somewhat from the Smart Chart curve I don't
sweat it or jump through hoops to manipulate.  It's a theoretical curve
anyway.  The shape should fall in some range heavier to lighter but the
exact shape can vary somewhat.  There are times when a heavier SW is
desirable such as when the sounboard/rib assembly is quite heavy and you
need more mass.  You won't have that problem on one of Del's designs.  The
boards are very responsive.  If you are using Ronsen hammers with light
maple moulding, you should be able to achieve the desired weight with only
modest tapering.  Though each set varies somewhat they are generally not
that heavy to begin with.    

 

Advice earlier about the width of the flange is important if your piano has
that problem-not all of them do.  As I see the data you put in, a medium
weight hammer with at 17 mm flange will not produce any BW/FW conflicts.
Alignment, convergence and all that is another issue that should be analyzed
carefully but a move from 16 to 17 mm will not create any problems there
anyway.  

 

I save the 18mm hanging for action disasters that can't be addressed any
other way for whatever reason.  I don't prefer it and if you go with an 18
mm knuckle you must have more substantial hammer weights or you can have
problems.  Actions such as Ron Overs (from Reno), which had 20 mm hanging
had very heavy hammers which were, I presume, needed for the soundboard
assembly design as well as to function properly with the 20 mm hanging.
There can be similar problems if the hammer gets too light with a 17 mm
knuckle.  You can see this if you've ever switched out a very light original
Steinway hammer onto a 17 mm hanging (DAMHIK).  What I have suggested,
however, doesn't approach that.  Each knuckle hanging, in my view, has an
optimum range of hammer weights associated with it.  I've never really tried
to figure out exactly what that is but basically the shorter the hanging the
lighter the hammer and vice versa.  Compensating for a short knuckle hanging
with a heavy hammer by having a low key ratio doesn't produce as nice a
feeling action as properly matching the knuckle placement with the hammer
weight.  It probably has something to do with inertia with a short knuckle
hanging/heavy hammer, and speed of return and a tendency toward bouncing
hammers with a long knuckle hanging and lighter hammer, but I've never tried
to quantify it.  Anyway, with a 16 (or 15.5) hanging I try to keep the
hammer pretty light.  As the knuckle moves out, the hammer should get
heavier-at least under ideal circumstances.   

 

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: Wednesday, July 04, 2007 1:20 PM
To: Pianotech List
Subject: Re: Action Ratio and Dip and Blow and Etc.

 

Hi David. Thanks for your input. I have a couple questions about hammer mass
with Del-designed bellies. I did some experimenting with note #40. The
picture you are referring to was actually note #16, not #20 - but that
doesn't really matter. You are suggesting a SW for note 20 of 9g or maybe
even a little less. That's a light hammer! But then, your reasoning may be
right on, considering the new efficient Del-designed belly in this piano. 

 

Do you set your hammer weights using Stanwood's Smart Chart SW curves? A 9g
SW for note #20 falls about 2/3 of the way up from the extreme light curve
to the light-medium curve. Staying on the same curve, note #40 should have a
SW of about 8.0g or 8.1g, according to the Stanwood curves. That curve would
have and A0 SW of about 9.5g and a C88 SW of about 4.2g. Is that what you
are thinking? I realize, of course, these Stanwood curves are nothing set in
stone - a particular piano may do better with a curve that crosses into
other zones on Stanwood's Smart Chart. What SW curves do you find working
best with Del's designs? What kind of hammers are you favoring? Probably a
Ronson. With what kind of felt?

 

Note #40 originally had four 12g leads in it. I put a 17mm knuckle and an 8g
SW hammer on - popped out the two leads closest to the key front and
measured DW - it is now less than 50g. If a light SW range works well for
this piano belly, it would seem my problems are pretty close to over. 

 

Part of my initial confusion may also be related to info on the Abel
shank/knuckle data. They offer two shank/knuckle/flange assemblies for old
Knabes - their data indicates that one has an 18mm core-to-center distance,
and the other is 17mm. The shank assemblies I received from Brooks have a
16mm distance. I'm not sure why. I'll give Wally a jingle on Friday.

 

Terry Farrell

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

Personally, I don't like going to 18 mm for the knuckle.  If you do,
consider repinning the balancier flange so you can put more tension on the
rep spring.  Otherwise, you will have to regulate it too close to the edge
and the jack return can suffer.  If the picture below indicates the strike
weight of note 20 at 11.9 grams, I'd use a lighter hammer.  I don't see why
you need a 10 gram hammer at note 20.  Nine grams should be plenty for your
6'4" Knabe with new and sensitive soundboard and you could probably go even
lighter.  Moving the knuckle (better to have bought the shank with the
correct knuckle to begin with) to 17 mm and taking 1 gram off the hammer you
will achieve approximately the same goal as moving the knuckle to 18 mm
(maybe a little better in fact).  You won't have to compromise jack angle
either.  To figure out how much lead you can remove it is 1:1 inverse ratio
FW: BW.  So if you want to add 6 grams of balance weight you subtract 6
grams of FW.  (Makes sense, right?  You take lead out of the key and the
touchweight gets heavier.)  That's a 12 gram lead located in the middle of
the keystick (between front and balance rail).  Don't get too hung up on
3-2-1-0 configuration.  You're slightly better off with a 4-3-2-1 set up
with the leads moved closer to the balance rail. 

 

SNIP

David Love

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