Action Balancing/Leverage Quagmire

[Tom Servinsky]

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BTW: What is a wippen saddle cushion? Is that a different term for the =
heel cushion?
Yes, same thing.
Tom Servinsky
  ----- Original Message -----=20
  From: Farrell=20
  To: Pianotech=20
  Sent: Friday, August 05, 2005 6:38 AM
  Subject: Re: Action Balancing/Leverage Quagmire


  Hi Tom. Thanks for your input. Comments below:

  Tom Servinsky wrote:
  Are these original parts, except for the hammers?=20

  No. Newish (few years old) hammers, shanks, knuckles, flanges, =
wippens.

  Original keybushings with well worn key pin grooves.=20

  Yes.

  Original wippens with excessive saddle/ capstan grooves?

  New.

  Pinning?

  If anything much of it is loose - what we looked at - didn't fully =
evaluate.

  Verdi Gris?

  No.

  Too many times action geometry concerns are confused with the basics. =
Excessive friction from the keybushings/ keypin relationship can affect =
the outcome dramatically.  My advise before any drilling and leading is =
considered would be to thoroughly lubricate all contact =
points...keypins, capstan, knuckles, jack tops, and even the keybushings =
and wippen saddle cushions.
  I assure you that your findings will change dramatically.
  Incidentally, a tip that I picked up from my last Steinway factory =
seminar was centered around this issue. The techs are now lubricating =
the keybushing felt and wippen saddle cushions with Protek Pro Lube, in =
addition to lubricating the keypins and capstans.  The differences in =
release are outstanding.
  Remember: measure twice cut once!

  No doubt, friction is an issue with this action, but the keys are =
relatively free and many notes have normal friction. On the few high =
friction notes we put the long-distance knuckles on, friction came right =
down to 12 grams or so. So yes, friction needs to be addressed on this =
action because it is erratic, but with five leads in the keys, FWs that =
exceed the Stanwood ceilings, and an action ratio upwards of 7, it seems =
clear this action needs a bit more than friction management.

  Thanks though. Some good point.

  BTW: What is a wippen saddle cushion? Is that a different term for the =
heel cushion?

  Terry Farrell


      Hello Action Balancing Aficionados,

      Today I spent a good part of the day with Phil Bondi (who is =
currently dodging thunderstorms along southbound I-75) diagnosing an =
1880s S&S model A 85-note action that plays like a Mack truck.

      Because two heads are better than one, and as we found out, they =
are likely better by an exponential function, we have at least four =
times as many unanswered questions as either one of us could have come =
up with working alone!

      We actually did improve one thing right off. The drop screws were =
turned WAY down to make the pathetically hung crap hammers check - sort =
of. They were so far down that the rep levers were being depressed at =
less than half blow. We turned them up and that made quite a difference =
right away. But still, the action was sluggish.

      We measured upweight (UW), downweight (DW), key ratio (KR), strike =
weight (SW), wippen weight (WW), knuckle-to-center distance (KC) and =
front weight (FW) on all the Cs and C#s. Our objective is to =
characterize what changes can be made to this action to make for a =
normal to light touchweight. All results discussed herein are in grams =
and millimeters.

      We also examined magic lines and did the measurements to calculate =
overall action ration as specified by Ron Overs.

      The action had shanks with knuckles 15.7 mm away from the flange =
center pin (is that the right distance Phil?). And it had five leads in =
the bass keys and two in the trebles.

      The capstan/wip-heel actually intersected the magic line just =
after key travel started (not too horribly bad). The knuckle/rep-lever =
interface started at a full knuckle below the line and ended with the =
line about half-way across the knuckle at full key depression (pretty =
bad).

      For anyone interested in a painful experience, I will send you my =
spreadsheet with all the data upon request. For those others more =
sensible, but still reading this, I will summarize below:

      DW ranged from 49 to 63. UW ranged from 18 to 28, friction (F) =
ranged from 12 to 19.5 balance weight (BW) ranged from 34 to 45.5,=20

      What would make the BW so inconsistent?

      FWs are from at Stanwood's Front Weight Ceilings to about 4g over, =
KR is .55 for naturals and .53 for sharps, average WW is 16.5, SW ranged =
from heavy-medium in the treble to just into the light zone in the bass, =
action ratio (R) ranged from 6.7 to 7.5 and averaged 7.1.

      Clearly, the leverage of this action is horrible - too high. We =
experimented with a 17mm and 16.5mm knuckle-to-centerpin distance =
knuckles/shanks. They seemed to function very well - you could regulate =
the notes quite well (we tried the 17mm on one note and the 16.5 on four =
notes). However, the improved leverage dropped all the DWs to around 41 =
and all the UW to about 16 or 18g.=20

      Looking for a bit of input here - this is too light, yes? Too =
light DW and the low UW will produce poor repetition, yes?=20

      Friction on the high friction notes dropped to 12 or so and BW =
dropped to 28 to 30. Calculated R goes from and average of 7.1 to 6.2 =
with the 16.5mm knuckles - likely down to about 6.0 with the 17mm =
knuckles.

      Using the Overs action ratio method (we did not do actual =
measurements with the 16.5mm knuckles) I estimate that the knuckle =
change would drop the action ratio down from the original average of 6.4 =
to 5.9

      BUT, these keys have a whole bunch of lead in them. We are =
thinking that, at a minimum, this action needs the knuckles placed out =
at 17mm from the flange center pins to improve leverage. Then, that will =
allow one or two leads to be removed from each key - remove enough lead =
to make the DWs in the 50 gram range and the upweights will gain a =
similar amount - around 10 grams or so and end up with about 27g UW.

      Ultimately, I think, this piano needs a complete releading =
(setting gradational FWs) new hammers, shanks, knuckles and flanges and =
gradational SWs (on some nice SW curve).

      Don't know exactly what the piano owner will be willing to do - =
apparently it is a not-so-well-to-do church. Phil has the action at this =
point to evaluate it.

      Anyone care to comment on our thinking here? Neither one of us are =
experienced with this balancing methodology enough to decide exactly =
what to do on our own. And we recognize that maybe we need to do a bunch =
more measuring also. But we have a start.=20

      We'll be very interested in input. Thanks.

      Terry Farrell
      (I wonder if Phil managed to drive the 135 miles home in the time =
I took me to write this email?)   :-(
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