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Half Balance Rail Punchings for Leverage Adjustment

  • 1.  Half Balance Rail Punchings for Leverage Adjustment

    Posted 01-11-2020 10:30
    I'm considering slightly adjusting key ratio, in a basically completed action job, using the half balance punching method.  In theory this would be the quickest way to make a leverage change.

    As I've never done it before, my hesitation is that it has to muck up key level, which for me, blows away my ability to do a complete regulation out of the piano, in the shop. That would kill the apparent efficiency of the method, and impose a large hidden cost, at least in this case.. That's a big down side. If key level is lost, as key level, was already done before I took the action to the shop, since the bedding and level is the foundation of my out-of-the-piano regulation precision, it imposes an unacceptable inefficiency.  Better off then, just to move the capstan a little.  So my question, for those that have done it is, have you been able to retain keylevel, or not, when doing the half punching trick?

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------


  • 2.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-11-2020 11:17
    It's been my experience that the key level doesn't change. The key at rest is sitting on the back half of the punching and the only variation you would be introducing is the glue used to adhere the half punching to the key. If you know the key height and can accurately duplicate the bedding in your shop I'd recommend using a thin veneer strip behind the balance pin instead of cutting the punchings. Re-leveling afterwards will cost you an hour maybe two and it's easily reversible. David Love has written a detailed description of this technique on this forum within the last year or two.

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    Karl Roeder
    Pompano Beach FL
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  • 3.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-11-2020 14:25
    Jim,
    I'm on my phone so won't get into extended discussion about the leverage aspect now. Regarding key level, since I don't have a Chris Brown bench and don't trust my ability to duplicate the keyed will enough, I set samples (C's and maybe G's) using split punchings and the fill in on bench using a light 1/2 octave stick. You could retain (as in: don't modify) samples until you've completed the rest, then do the samples. That would be a little harder using Karl's veneer method but you could figure it out. 
    Doesn't it just sustain the initial ratio through completion of the keystroke?

    ------------------------------
    David Skolnik [RPT]
    Hastings-on-Hudson NY
    917-589-2625
    ------------------------------



  • 4.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-11-2020 17:08
    Doesn't it [the half punching] just sustain the initial ratio through completion of the keystroke?

    Yes it does, even better than the original setup. However, it is better to think of this modification as optimizing the key ratio, not changing it. The typical key sitting on flat, flexible washers of paper, cardboard and felt does not pivot cleanly at a single point, but rather rolls over what amounts to a number of points. Keys pivoting on the Steinway accelerated action bearings do better in this regard.

     

    The half-punching defines a definite ledge precisely at the key's pivot point resulting in a crisp and uncompromised rotation as compared to the rather inexact rolling action it otherwise undergoes. The key, if you will, is happy to "fall off the ledge" at the slightest provocation of the pianist.

     

    It is even possible to locate the cut (or half-moon) punchings behind the balance pin. This, then, will change the key ratio and noticeably increase the mechanical advantage of the key. The motion taking place at the key pin and balance hole, however, involves some sliding. See Mario's book, page 313 for more info on this.

     

    Friction may also be lowered a bit, but I have not quantified this.


    Worth a try,  Jim. Don't know how much of a mechanical advantage you hope to gain.


    Good luck. -- Nick G







  • 5.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Posted 01-11-2020 20:29
    Hi Nick...I bagged it and moved the capstan 3mm. Turned out this also lined up better with the heel center, so it was a win-win. As you mentioned,and as I have seen when experimenting with this balance punching thing, ratio adjustment from this move is really pretty "meh", technically speaking. 

    Moving the capstan, actually all  I have to re-regulate is the blow/hammer line  to meet my already set dip/aftertouch. This leaves all the foundation conditions intact as well. 


    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 6.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-12-2020 08:14
    Jim -
    So, to review (as in: please correct or clarify):
    - in your above response you use the word 'capstan' in the singular, but is it correct to assume that you were dealing with the entire keyboard? If so, that would appear to be an equivalent amount of extra work.
    - while you didn't specify, it would appear that the ratio was too high.  What were the symptoms?  
         - what was key-stick ratio?  length of front arm? rear (to capstan)?
         - down and up  weights (range)?
         - to retain your dip and aftertouch, you had to modify your blow.  What was it before and after?
    - while you say that you don't observe Stanwoodian protocols (as per your post to the Key bushing Caul size thread as copied below), could you make any correlations to the parameters you expressed there?

    I don't do weight balancing metrics aka Stanwood, or even use the data they generate. Rather, the system is low inertia at the hammer, slightly elevated system leverage, minimal lead, usually none starting mid notes of the 30's, all lead in back of the mid point of the front lever, with elevated DW, in the low to mid 60's in the bass graduating to mid 50's in the treble.  (January 10 2020, JI)


    ------------------------------
    David Skolnik [RPT]
    Hastings-on-Hudson NY
    917-589-2625
    ------------------------------



  • 7.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Posted 01-12-2020 14:18
    Ratio was 5.75 using the measured hammer rise vs measured key dip technique. 
    I changed bass to  from 5.75 to 5.25  (3mm capstan move), up through the tenor. Graduated the capstan move from 3mm to 2mm within alto capo section. I left the top section at 5.75. This shift in ratio is common in older instruments, at least as best I can tell from vintage actions that have come into the shop. .  

    Dip stays at .390, aftertouch prioritized at .040, blow takes up the difference as necessary. Before the change, blow was 1-7/8 in the 5.25 sections, instead of the current 1-3/4, and aftertouch was a little strong of my target .040.

    I'm doing the graduated leverages on this action, because I like how the high treble feels as it is. I can avoid too much back leading to reach my elevated treble DW's, if the ratio is slightly elevated.  Down further in the compass, the elevated DW's I target don't work as well if there is too much lead in the keys, so I wanted to lose some lead.  All of it is in the back half of the front lever, in the bass and tenor, but still too much to work with elevated DW's.  

    I don't do the 38g BW weight metric thing, and actually dislike the feel altogether, so I approach the whole thing differently. My approach is similar to what Ed McMorrow does, but not exactly the same.

    I am looking for this combination of parameters in my actions:

    1-Lighter hammers - HW 9-10g at note 1, with a simple linear slope to low 3g HW at 88...this graduation changes depending on what the manufactured hammer set will give me. Concert instruments note 1 elevated to 11-ish, but 88 still stays as light as I can get it.

    2- As little lead in the key as is practicable. I want the finger to have un-encumbered connection to the movement of the hammer, and really dislike the lead imposing its opinion on the whole experience. There is lead, to be sure, but I said, as little as practicable. This will mean, no lead past the half-way point of the front key lever. This mostly means, during weigh-off, FW changes of 10-12ish g for the naturals, and usually a little more for the sharps( say 1-2 max 1/2" leads well in towards the balance rail.

    3- Elevated DWs. Depending on the overall key length, (ie less for short key baby grands and more for longer key instruments), note 1 has about 60g for short key pianos, and 65-ish for longer key pianos. Graduating to about 50-53-ish g at 88 for all pianos. This higher DW, when a system is low inertia, provides the necessary resistance one needs to remain in contact and in control of the hammer, and does not at all "run away" from the fingers as is cautioned will happen. The experience is about the way the acceleration of the hammer per finger movement feels, as opposed to the way a static 38BW touchwieght feels, which to me is defined by how much I have to argue with the lead's inertia and momentum.  It is different than a 38BW setup, since you are mostly accelerating the hammer, and not accelerating lead. BW's FYI are in the mid to high 40's, and is just not that meaningful in this kind of set up.

    I say I don't use the standard BW metrics, because they assume as a design value, ie the value of lead in the key, which I don't subscribe to. Obviously the BW metrics work and make pianists happy, but so does this approach...so its a "many design scenarios can work" thing, as long the design scenario is internally consistent..ie, there is no one correct answer on how to proceed.  

    4- In designs, I standardize regulation parameters  dip .390", aftertouch .040", blow 1.75", letoff varies between 1.5-2mm depending on the venue of the piano, and impose them, if the action is not set up to provide them. These standardized regulation parameters allow me to know that actions will be consistent and predictable piano to piano, and greatly simplifies the design process. If the regulation parameters are as targeted, and hammer weights as targeted, and the lead patterns as mentioned, all within a reasonable bandwidth, the actions will all have a reasonably consistent feel action to action. The standardization of all the above parameters takes the guesswork out of picture, in a similar way that the weight metrics seek to take guesswork out of the picture.            


    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 8.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-14-2020 19:41
    (Note correction in first paragraph should read *inertia* not leverage)

    The lead actually plays a pretty small role in the overall inertia.  Most of the inertia comes from the relationship between the leverage and the hammer mass (about 70%).  The key (including the lead) accounts for the other 30%.  The wippen contribution is negligible.  In other words, too much lead is not what is responsible for high inertia, a bad relationship between leverage and hammer mass is and that will result in too much lead to achieve a reasonable BW.  Repositioning lead slightly forward or aft also doesn't really affect the *inertia* that much.  Again, problems with too much lead, or leads needing to be located too close to the front of the key, indicate a poor relationship between leverage and hammer mass.  

    Naturally the inertia will be higher in the lower part of the piano because the hammers have more mass.  Using a graduated capstan line can change that (as you've indicated) but, personally, I would find a keyboard with uniform inertia unwieldy in the treble if it at all compares to the bass.  I've tried it in the past, didn't like it at all.  By the same token a very low inertia is unpleasant as well.  As you mention too little and you lose connection to the key.  I've certainly found myself adding mass to hammers on some 5.3 leverage actions when pianists complained it was too light.  Mostly those additions were in the top half of the keyboard.  

    I agree that if you push the leverage down to 5.25 that you will want a higher static balance weight.  However, I don't see you you can possibly accomplish a 3.90" dip with a 5.25 leverage (if that's actually what it is--taking accurate measurements with dip/travel is tricky).  I've seen plenty of 5.3 targeted leverages and the dip is nowhere near that low, not without a very short blow distance.  Too short for anything I would want.

    My preference is still for mostly uniform leverage.  My hammer weights are much like yours, on the lighter side for Steinways, certainly.  Their original target worked well, in my opinion, for those relatively light belies and low tension scales.  Concert grands are another animal and pianos with heavier bellies (Yamaha and Kawai) need something either firmer or heavier or both, depending on the condition of the belly but this is another discussion.

    Since the amount of lead needed at a particular BW for a specific key is a real clue into the hammer mass/leverage relationship you can use that as a guide for how to set up the action.  That's the "actions to die for method", basically.  Using Stanwood maximums as a guide, targeting about 80-85% of his maximums for a reasonable BW (36-38g) yields a pretty optimized level of inertia.  

    There's a good article which I'll post if I can find it.  Several years old now but outlines the contributions of each component in the dynamic model.  Everyone who does any action work should read it.

    Edit:  Here's the link:  http://pianobytes.com/ActionAnalysisinertiaa.htm

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



  • 9.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Posted 01-14-2020 20:51
    Inertia is a force F that needs to be applied to the mass M in order to develop acceleration A . Second Law of Newton. This force is zero or next to zero if no acceleration ( First Newton law) or very little acceleration. Acceleration is equal velocity that mass develops from rest to the end of first second of movement(well, in simpliest case). Other words no inertia or very little inertia during slow or slowest legato .So little , that it can be ignored for engineering purposes. It shows on fast play , quick staccatos and so. But in such case other forces and properties should be considered and main is Flexebility of the parts. Main source of dynamics of any mechanical system is such flexibility, mass and distribution of mass is secondary. Flexibility is so important that ignoring it and counting only leads and their position on the key and mass of the head is same as throwing baby together with water.Not much studies done in such field applicable to piano action.

    Alexander Brusilovsky




  • 10.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-12-2020 14:55
    Hi Jim,
    With a 3mm move toward the player, that will lower the both wippen ration and the key ratio, which lowers the action ratio more than one might think. For original keys it can be good solution for really high action ratio, especially in your case where the wippen lift point works is improved.

    I dislike using the half balance rail punchings except in an emergency since you have to glue the punchings to the key.

    One other thing I like to check (and I suspect you already probably did this) is the magic line or half-stroke - a straight line from bottom of key balance pivot to wippen center for lowest friction We check this before we design every new keyset, to make sure it is at least improved, if not optimal by our typical balance rail and key ratio redesign. With a new keyset on an older grand we are typically moving the balance rail away from the player to reduce the key ratio. 

    For those not familiar with magic line or half stroke, WNG has the best explanation of the magic line / half stroke I've ever seen - on their web site: (with lots of pictures)

    https://technicians.wessellnickelandgross.com/media/pdfs/half_stroke.pdf

    Since the magic line is slightly different on black and white keys, I don't mind if the magic line is straight for white keys at just a smidge more than 1/2 of key travel, which minimizes the friction on black keys. That's assuming you're not using WNG parts which have a better, a really cool solution for this issue - see above link.

    If your 3mm move improved the magic line, then it was a triple win-win-win.  :)

    PS, loved your class at the national on stacks, spread and jacks, really learned a lot! -dlr

    Best regards,

    ------------------------------
    Dean Reyburn, RPT
    Reyburn Pianoworks
    Reyburn CyberTuner
    1-616-498-9854
    dean@reyburnpianoworks.com
    www.reyburnpianoworks.com 
    Facebook: www.facebook.com/dean.reyburn
    ------------------------------



  • 11.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Posted 01-12-2020 15:36
    HI Dean,

    The half stroke/magic/line of convergences line was fine in both iterations. I used to really fret it, but after observing many actions and their relationship to that line, I am in agreement something John Rhodes mentioned to me in one conversation a while ago...ie, as long as the convergence happens somewhere in the stroke, it will be okay...and that has been my experience. 

    I have seen way-off magic lines, mostly on Steinways where the string height was 1/4" too high. In those cases, the friction levels were way off the charts by 15g or so, over normal limits...very interesting. Plus, you could visually see the capstan scraping along the heel cushion in a linear fashion, rather than a quasi-pivoting movement. Actually one way to diagnose this quickly, is to simply observe whether there is a quasi-pivoting movement at the capstan/heel contact, or a back to front movement, during the stroke.  Its actually quite visual and clear when its off.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 12.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-13-2020 10:57
    Hi Jim,
    I agree with you and John on this, it will be ok as long as the key goes through the magic line at some point. But ok isn't necessarily optimal. 

    If the magic line is crossed very early, say right at the beginning of travel, the friction will certainly be higher, and will be especially high for the black keys.

    When we build a new keyset we use both a spreadsheet and a CAD model which shows the problems in the current design  including magic line. Since *everything* is in play when we build a keyset, the engineer in me just can't resist fixing all the problems I can, and optimizing things like stack position, action and key ratio etc...  We typically offer to move the stack for our rebuilder customer as needed, or recommend changes for them do it if they want.

    Oh, some time ago you mentioned issues with new keysets and key bushings. I'd bet we're as fussy as you are about key bushings having done a zillion jobs over the last 40 years. Take a look at my facebook page, we have a short video of our method using German Jahn-Pianoteille pre-glued bushing cloth. This material and method produces the most consistently high quality job I've ever used, and it's what we install on all new keysets. (I don't miss my glue pot at all.)  Since we are always bushing brand new keys with CNC accurate mortises, and the same size key pins every time, it's pretty easy to get it right.  :) 

    Best regards,

    ------------------------------
    Dean Reyburn, RPT
    Reyburn Pianoworks
    Reyburn CyberTuner
    1-616-498-9854
    dean@reyburnpianoworks.com
    www.reyburnpianoworks.com 
    Facebook: www.facebook.com/dean.reyburn
    ------------------------------



  • 13.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-13-2020 16:36
    The method I wrote about was inserting a thin shim under the back of the punching (doesn't work on an accelerated action), and included a picture of the method.  That does change the key level sligihtly (depends on the thickness of the shim, I use thin maple veneer so it doesn't change it enough to have to reset the key level).  With a lowering of the leverage you need increased dip anyway.  And with the shim you will have to reset the blow distance and possiblyl the dip.  If you insert the shims carefully the keys remain level.  Cutting the shim, as Nick points out, doesn't change the initial leverage and isn't that effective, in my opinion, since most of the inertia we feel is at the onset of the key stroke when we have to start the key moving it isn't nearly as beneficial.

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



  • 14.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-13-2020 18:32
    Exactly where the point of pivot lies depends on a number of things. Most balance rails are beveled from the middle of the balance pin, so if the felt bushing is fairly thin, and there isn't too much paper and card, the pivot will be close to the middle of the hole - perhaps more so than with the Steinway accelerated thingees. Often we find sharps that have been beveled from the middle of the hole to a point maybe 15 mm forward, giving the same effect for the sharps. 

    Interestingly, some of the very earliest piano keys, made by Zumpe in the 1770s, shaped the bottom of the key to pivot/roll, in the inverse of Steinway's bearings.
    rounded pivot on bottom of key


    ------------------------------
    Fred Sturm
    University of New Mexico
    fssturm@unm.edu
    http://fredsturm.net
    http://www.artoftuning.com
    "We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
    ------------------------------



  • 15.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Posted 01-12-2020 10:10
    Hi, Karl,
    Can you point me to the David Love posts on the veneer strip method of changing the key ratio.

    -- Begin Rant --
    I have tried searching the pianotech discussions for David Love, balance rail, etc. and unfortunately the search function is nearly useless.  It returns multiple hits for each discussion thread (one for each post in a given thread) and many hits that have no relevance to the search terms.
    -- End Rant Here --

    Thanks!

    Eric

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    Eric Schell
    ericschellpiano@gmail.com
    Austin TX
    512-363-6236
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  • 16.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-12-2020 12:45
    Mr.Schell,
    I wish I could. I can't find anything by Mr. Love written in 2015 or 2016 after wasting an hour trying every search parameter I could think of. The awfulness of this website is truly breathtaking. Harrumph!

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    Karl Roeder
    Pompano Beach FL
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  • 17.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-13-2020 08:15
    David Love's article appeared in June or July 2015, I believe.  I seem to recall reading it while attending the Denver convention that summer.

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    Kent Burnside, RPT
    Franklin TN
    615.430.0653
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  • 18.  RE: Half Balance Rail Punchings for Leverage Adjustment

    Registered Piano Technician
    Posted 01-13-2020 17:05
    Eric

    Picture attached.    


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