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Change key dip?

  • 1.  Change key dip?

    Registered Piano Technician
    Posted 06-08-2022 16:43
    I am regulating a 1979 5'-8'' Chickering grand and the key dip is currently at 3/8''.  Everything is working but is there anything to be gained by changing to 10 mm?

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    Mike Ello RPT
    Richmond TX
    (281) 633-0622
    mike@ellopianoservice.com
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  • 2.  RE: Change key dip?

    Posted 06-08-2022 17:04
    Mike,

    You mean, besides more aftertouch? If the jack is clearing the knuckle sufficiently on a soft blow with .375" of dip, it may be a case in which more is not necessarily better. On the other hand, more AT could facilitate greater blow distance (= more power, different action feel), provided that it would not make the jack bury in the repetition lever window felt.

    Alan

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    Alan Eder
    Valencia CA
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    Original Message


  • 3.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-08-2022 17:19
    Mike,

    What Alan said.

    Assuming aftertouch is as it should be, arbitrarily increasing dip by an additional ~ 0.019" might be asking for trouble on several levels, including the possibility of jamming the jack and lack of control on soft blows. Finally if the action is basically functioning properly and if the customer is happy, then so are you. But if the pianist is complaining that the dip feels shallow compared to the church piano,of a friend's piano, then that's different.

    BTW, where and how are you measuring dip? Is the dip actually 0.375" (~9.5 mm) at the very end of the key? Or are you using 3/8" dowel placed crosswise at the front pin?

    Nick

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    Nick Gravagne, RPT
    Mechanical Engineering
    Nick Gravagne Products
    Strawberry, AZ 85544
    gravagnegang@att.net
    928-476-4143
    ------------------------------

    Original Message


  • 4.  RE: Change key dip?

    Posted 06-09-2022 10:07
    Action ratio is the most sensitive parameter for the pianist . Any regulation should start from setting AR as low as key deep and AT permit. All other parameters - Balance weight ,inertial resistance, feel of action controll , etc, derive from AR. Piano action is transmission first of all!

    Alexander Brusilovsky


    Original Message


  • 5.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-09-2022 11:03
    Is there a conflicting duality between control (lower AR) and power (higher AR)?

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    David Skolnik [RPT]
    Hastings-on-Hudson NY
    (917) 589-2625
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    Original Message


  • 6.  RE: Change key dip?

    Posted 06-09-2022 14:05
    Mike, check how many leads transitional keys have. If it more than 3 your action most likely has excessive AR. It had to be corrected first. Any manipulation with Blow Distanse, key deep, amount of aftertouch will not improve the action.
    AR correction on most actions could be easily done by capstan repositioning ( closer to pianist equal lower AR) and in some dramatic cases that USA pianos of 70 th famost for - expanding wippen hill .

    Alexander Brusilovsky


    Original Message


  • 7.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-09-2022 18:39
    As I understand it, high ARs deliver greater acceleration, but to make the inertial force manageable, should have lighter hammers. Lower ARs make heavier hammers more "moveable", at the expense of lower acceleration. It's quite likely that the striking force (hence, power) can be equivalent between two action set-ups: one with light hammers on a high AR, and the other with heavier hammers on a lower AR. Hammer weight and AR are both terms in the same compound integral formula for force delivered to the string. The only difference should be how quickly each hammer decelerates and is rebound from the string. The impact velocity of a lighter hammer on a higher AR will be greater than that of a heavier hammer on a lower AR. But here again, in the force formula, it's likely to be a wash. 

    But the amount of aftertouch doesn't have much to do with power, because during that part of the stroke, "the train has already left the station". It's my belief that if a pianist notices aftertouch, if there's a note-by-note discrepancy of 10 mils between a constant dip (say, 0.390") and a constant aftertouch (say, 0.040") - as is very common, given wood, leather and felt - a pianists, given a constant dip, will find the 10 mil discrepancy in the aftertouch far more obvious, than in the constant aftertouch situation where that 10 mils is placed in the dip. It's a 25% error vs. a 2.5% one.

    ------------------------------
    William Ballard RPT
    WBPS
    Saxtons River VT
    802-869-9107

    "Our lives contain a thousand springs
    and dies if one be gone
    Strange that a harp of a thousand strings
    should keep in tune so long."
    ...........Dr. Watts, "The Continental Harmony,1774
    +++++++++++++++++++++
    ------------------------------

    Original Message


  • 8.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-10-2022 01:06
    I think Bill is essentially correct. The only thing I would add re lighter versus heavier hammers, even if the ARs compensate for difference in power as a result of differences in mass, is that lighter vs heavier hammers will result in differences in timbre.  I would always select the most appropriate hammer for tonal considerations and adapt the AR to accommodate that hammer weight curve. Tone first.

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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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    Original Message


  • 9.  RE: Change key dip?

    Posted 06-10-2022 01:17
    Amount of kinetic energy that hammer accumulated is only one , and actually not most important factor how hammer- string interaction happens. Kinetic energy is proportional to the mass , but proportional to the velocity in second power. So velocity variation is main factor, not a mass variation.
    Statement that higher AR brings higher velocity could be truth only for linear system, which piano action is not. All parts are flexible and all contact points are compressible. Considering that higherAR always(!) results in additional keys leading and inertial resistance increases ability to accelerate or by other words ability to achieve velocity in shorter time might be completely opposite of what one expected.
    There are no any benefits for action specified for 45 mm blow, 10 mm dip to have AR greater than 5!.



    Alexander Brusilovsky


    Original Message


  • 10.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-10-2022 08:48
    To all responders,
    I am installing a new set of Abel Naturals on this Chickering and then regulation. Most of my jobs have been on newer pianos with 10mm or greater. I even modified my Jaris sharp tool (glued a small piece of punching to the top piston piece) to show the larger dip.
    I have learned some new “checks” to consider for all similar jobs going forward from all the feedback I received. As it turns out, 3/8 dip works out best on this Chickering. We are blessed to have this forum to exchange ideas. Thanks for all your insightful submissions.

    Mike Ello, RPT


    Original Message


  • 11.  RE: Change key dip?

    Posted 06-12-2022 09:32
    Responding to Mike Ello's post regarding dip on the sharps. On a vertical piano the keys lift the wippens to the same level. On a grand, the sharps lift a little higher but to insure the dip is identical to the naturals, the jacks should be aligned at full dip . The back checks need to also be aligned on grands and verticals.

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    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
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    Original Message


  • 12.  RE: Change key dip?

    Posted 06-09-2022 14:19
    Correlation between raising of power with AR raising could be big misconception. I didn’t have chance to see reputable studies on this matter. And it is not such easy, I believe.
    Perhaps lower AR gives better timing when finger is engaged with the action and hammer can accumulate more kinetic energy.
    Excessive AR always ends up with excessive leading and it is not such clear what that bricks in the trunk racing car will do.
    Deviation from action maker specification for Blow makes jack not perpendicular to the shank at rest, which affect how force applied to the shank and process of energy accumulation….
    Many other things involved….
    Good controll is always preferable action in my shop.

    Alexander Brusilovsky


    Original Message


  • 13.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-10-2022 00:54

    I don't quite agree with that. What's critical is the relationship between AR and hammer mass as that determines inertia. That's what pianists feel-the resistance to hammer acceleration. High ARs with low hammer mass are fine as are lower ARs with higher hammer mass.  What doesn't work is high ARs with high hammer mass (sluggish resistance to acceleration) or low ARs with low hammer mass (fly away).  

    But AR determines how the action regulates. Assuming you're not changing the blow distance or the aftertouch, lower ARs will necessarily result in deeper dip . So if the pianist is sensitive to deep key dip then low ARs may not be desirable. 

    Ultimately the required hammer mass for optimum tone determines the AR which determines how the action regulates. There's no free lunch. 



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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------

    Original Message


  • 14.  RE: Change key dip?

    Posted 06-10-2022 01:36
    If average hammer mass in transitional area ( bass to treble) is 9 gr. How many gramms would be considered as a heavy and as a light hammer? Please give numbers.

    Alexander Brusilovsky


    Original Message


  • 15.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-11-2022 01:01
    They are any number of postings discussing and illustrating the range of Stanwood weight curves. That's probably a good place to start. Average means nothing. Matching the actual weight curve of the hammers (or strike  weights if you prefer) is essential in getting an action that performs within a normal range of inertia. The regulation specs will always be a consequence of the AR.

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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------

    Original Message


  • 16.  RE: Change key dip?

    Posted 06-11-2022 01:26
    AR should be set up first! Modern actions with Blow 45 mm and Dip 10 mm require AR 5. Any deviation from 5 are troubles. Properly set up action should have not more than 3 leads in transitional keys. If it more than 3 ( have you seen 7? ) it is sign of excessive AR and such actions couldn’t perform well. Manipulation with hammer weight and leading to hide mistake in AR is bad idea!

    Alexander Brusilovsky


    Original Message


  • 17.  RE: Change key dip?

    Posted 06-11-2022 21:33
    What would be definition and numerical measurments for " Normal Range of Inertia "?

    Alexander Brusilovsky



    Original Message


  • 18.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-12-2022 14:01
    I think it can go either way, either hammer weight first or AR first.  Each will determine the other to some extent.  Of course there's a range of what is acceptable.  In terms of targeted inertia I find that key leading (or front weight) will give you a strong indication of whether you are in the range of "normal" or even ideal.  Several folks have programs to determine "inertia" both directly and indirectly.  I think Gravagne's program might actually give a numerical value, not sure.  The Fandrich/Rhodes progam (Actions to die for) doesn't give a numerical value for inertia but shows rather a sweet spot which necessarily reflects inertia for a target note (A4 I think).  The Stanwood approach seeks to find the proper place by an analysis of the FWs required to balance the action at some mid range level, at least that's how it's often used.  Obviously the inertia in any action varies from top to bottom because the hammer mass varies and ARs don't tend to.  

    I tend to use a quasi Stanwood system in which I target a FW of 80 - 85% of Stanwood FW maximums at a medium balance weight (my default BW is 37 grams +/- 3 grams.  If someone wants a heavier static DW then I'll go as high as 40, if they want a lighter static DW I'll go as light as 34.  The DW, however, simply represents the the minimum force to actuate the key and does not influence the inertia really which is more a function of the relationship between hammer mass (or strikeweight if you prefer) and AR.  That relationship is reflected in the FW at some standard BW. 

    So my approach is generally to establish an optimum FW and then manipulate the AR:SW relationship to achieve that goal.  A lower SW will result in a higher acceptable AR and vice versa.  Optimum SWs take into consideration the tonal requirements of the piano.  Some will want more mass than others.  With Steinway pianos, which is probably 95% of the actions I do, the traditional relationship is somewhat higher ARs and somewhat lower SWs with FWs around that 80 - 85% target.  Other pianos may have different requirements.  On vintage Steinways with original boards lighter hammers always sound better to me.  On new boards, depending on how it's made, they can sometimes accommodate more hammer mass.  I consider the new Steinways (NY) to generally have too much hammer mass (driven by dense maple moldings and fairly bulky hammers) that produces a tone which I don't particularly care for (too much "whump" and not enough clarity and a bit dull sounding) when compared to the original hammers which were much lighter.  In the original you get more clarity, better high partial development and a broader palette, IMO.  

    It's important to note that if you produce an action that has very low FWs at that target BW (37g) you will necessarily have a lower inertia action than one with higher FWs.  That higher inertia is not because of the FWs being higher, the FWs being higher reflects a relationship between hammer mass and AR that produces higher inertia. 

    So approaching it this way there are many things you can do.  For example, you can, say position the capstan to give you a key ratio of (Stanwood) .50, .51, .52 etc., whatever the action allows (note: I always turn Steinway slanted capstans vertical and so have the option to reposition them).  Set up your FWs by sample on several notes through the action and then figure out for those samples SWs.  Use those samples to establish a trendline (Excel) calculate the trendline formula and use that to establish the SW curve.  

    Or, you can work the other direction, set up a SW curve that is compatible with the set of hammers you have--and the tone you want--and then establish the AR by capstan position that achieves the desired FW:SW relationship and go from there. 

    There are many ways to approach this and you want to set up your priorities whether it's SW for tone, AR for regulation or whatever.  In the end the AR will determine your regulation specs vis a vis key dip.  If you are determined to use a hammer set which is very high you will need a very low AR and will have to live with deeper key dip.  Similarly if you find that a light SW curve produces the tone you want then a higher AR will be appropriate and that will produce shallower dip.  If you really are set on a specific key dip (I don't approach it from that direction) then you'll have to select an AR that produces the dip that you want. 

    But with respect to inertia, a low AR high SW system will produce something very similar to a high AR low SW system, the FW is a good check on that as guidance.

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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------

    Original Message


  • 19.  RE: Change key dip?

    Posted 06-13-2022 00:11
    David,
    When you are dealing with what you call inertia - do you operate masses and forces( linear movements) or momentum of inertia and rotation moments( circular motion)?

    Alexander Brusilovsky


    Original Message


  • 20.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-13-2022 10:04
    Hi Alexander,

    I hope you'll allow me to jump in here; David's clock radio probably reads 6A now. 2 things:
    1.) There should be no confusion that the motion in which inertia is being calculated is rotational (moments of inertial and angular momentum).
    2.) I'm not sure if ANYONE (Darrel Fandrich, Bruce Clark, etc.) is actually calculating inertia, outside of the R&D departments of the well-established factories. I do remember, maybe 15 years ago, that one of the people on this list (Steve Birkett) set to work created a thorough mathematical model of a grand action, on a grant to uwaterloo.ca from Steinway&Sons. We never heard the results of course, because these were proprietary. But Steinway wouldn't have made this investment unless they were unhappy with their R&D dept.'s model on hand.

    As you well know, the accuracy of an inertia calculation is only as accurate as the amount of data you can plug into the formula (the mass of every last little object in the system, plus that object's center of mass, plus the distance from that to the center of rotation). Most of us work by analogy.

    I also use David Stanwood's metrology (and don't begrudge the fact that it's based on static measurements). But for me, FWs are a good analogy for the total mass in the system, from whence inertia comes.
    1.) Reducing the 3-lever grand action to 1 (the keystick, with the weight of action parts on the backside and the counterbalancing leads in front), the FWs are an indication of the weight of parts (modulated by the AR) needing counterbalancing.
    2.) David Stanwood's solution to arranging the front leads in a way that satisfies both the counterbalancing of the gravitational force, and a smoothness in their moment of inertia, is probably no different from most factories (Stwy included): pattern leading for the majority of any key's FW load, and the remainder set by a "free agent" lead. David favors smooth moment of inertia (over the gravitational force) by having the "free agent" leads run a straight line from the first note in any section of the pattern leading to its last note. (For good reason: gravitational resistance is fixed, but inertial resistance is variable, in often unpleasant ways.)

    In that single lever reduction, gravitational resistance is the difference between the side, inertial, their sum.



    ------------------------------
    William Ballard RPT
    WBPS
    Saxtons River VT
    802-869-9107

    "Our lives contain a thousand springs
    and dies if one be gone
    Strange that a harp of a thousand strings
    should keep in tune so long."
    ...........Dr. Watts, "The Continental Harmony,1774
    +++++++++++++++++++++
    ------------------------------

    Original Message


  • 21.  RE: Change key dip?

    Posted 06-15-2022 09:01
    Bill, thank you for your respond.
    As I expected community obsession with “ inertia” has nothing to do with scientific dynamic analysis of the entire mechanism. Hammer head has substantial mass and covers significantly large displacement and accelerations respectfully, so dismiss it from the model would be the throwing baby together with water.
    Moment of inertia , small one or huge one doesn’t makes any difference under the pianist finger tip unless there are noticeable acceleration, which happens mostly on fast F and faster. On mP legato dynamic resistance could be ignored. I believe good static set up of the action is good enough to built good action.Smothing moment of inertia from key to key can’t be separated from including rest of the he chain, especially hammer as it could change entire picture.
    There are reasons why leads are not smooth at first place, that coming from not smooth everything else. Did anybody ever bother to measure deviation of AR from key to key?
    I am sitting in front ofSS L from teflon era. Shallow dip, after touch is way too excessive, 7 leads in the key #25. Still needs one more but no room for it… Can’t believe QC let it go… Obviously needs AR reduction.
    Haw what here called inertial smoothing will help to this poor thing?
    Alexander Brusilovsky


    Original Message


  • 22.  RE: Change key dip?

    Posted 06-12-2022 05:31
    My goal on so many American pianos is to maintain the historical AR which in so many cases is about 6 coupled with extremely light hammers and as large a blow distance as I can get with good aftertouch and still maintain a 10mm keydip.  This has produced the greatest dynamic range and finest tonal characteristics that I have heard in a piano.

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    Michael Evans
    Mansfield TX
    (817) 822-3591
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    Original Message


  • 23.  RE: Change key dip?

    Posted 06-12-2022 07:39
    Blow 45 mm, let off 2 mm . Lift is 45-2 =43 mm.
    Dip 10 mm.
    Action ratio for aftertouch 1 mm: 43:9=4.8
    For 2 mm: 43:8= 5.3
    With attention payed to jack-knuckle positioning , knuckle condition, jack ratio itself most actions can get after touch between 1 and 2 mm, with respectful AR in 5 area.
    WithAR 5 action no massive key leading need - bricks from the sports car trunk removed( is inertial resistance coming from those leads , not from hammer heads staples?).


    Alexander Brusilovsky


    Original Message


  • 24.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-09-2022 00:34
    The action regulates correctly when it produces the proper aftertouch. All other factors being equal, a higher action ratio will produce less key dip (with proper after touch) than a lower ratio. Many players are sensitive to key dip. Most concert players are not wedded to deeper key dip, not at all. It's one of the downsides of going low with ARs that require deep key dip. Many players will find that more objectionable than slightly higher inertia. 

    I would not arbitrarily choose to set the dip at 10mm if there is adequate aftertouch at  9 or 9.5. You're chasing the untamed ornithoid (wild goose) for no benefit. 



    Original Message


  • 25.  RE: Change key dip?

    Registered Piano Technician
    Posted 06-09-2022 20:16
    Quite a few have replied to Mike's inquiry. All this high level discussion aside - products from the American-Aeolian factory had a number of deficits. In the late 70s the hammers were being made in house, and the elderly fellow I saw making them was not highly skilled. In '78-79 I was working at a piano dealership in Cleveland that replaced the hammers on Mason & Hamlin with Ronsens upon delivery from the factory as a matter of course.
    The action parts may have been made in house (if not they were Pratt-Read, not their best era).
    The 3/8" key dip was, I think, the factory spec at the time.
    Maybe Mike is working with new parts - that would be great!

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    Patrick Draine RPT
    Billerica MA
    (978) 663-9690
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    Original Message