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Hammer weight curves

  • 1.  Hammer weight curves

    Registered Piano Technician
    Posted 07-21-2021 19:09
    Just wanted to show an example of where Stanwood style weight curves don't really apply and I don't really see that we should take pains to try to achieve them.

    On the chart below the blue line indicates my hammer weights after tapering and tailing.  The black line is the trend line (2nd degree polynomial whose formula is shown on the chart).  The orange line is my final hammer weight target in which I've added .3 grams to the trendline so I can add and not have to subtract weight (easier).  But note that the trendline curve is not the typical sloping curve that we see with the Stanwood zones.  Does it need to be?  I don't think so.  BTW these are a set of Blue points with uniform tapering.  Just for consideration.  



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


  • 2.  RE: Hammer weight curves

    Posted 07-21-2021 20:54
    I pay no attention at all to the Stanwood curves, or frankly any curves. My goal is even progression note to note. The curve will be determined by the moldings and molding densities that are unique to each set of hammers. So, I take sample hammers at the beginning and end of each section, weigh the samples, see what weight reduction will allow me to reduce them to, compare that to my general weight targets are for that action, reduce the samples to target (I'm always reducing). Then I just graduate to the targets using an Excel linear trend. Just for yucks, here is a screen shot of a graph from a recent really nice sounding, excellent action.


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


  • 3.  RE: Hammer weight curves

    Posted 07-21-2021 21:03
    Jim, I assume that light-weight curve is just of hammer weights. Do you weigh the shank SW's and place similar weights together?

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    Regards,

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


  • 4.  RE: Hammer weight curves

    Posted 07-21-2021 21:22
    No. I do not weigh or bother calculating SW. Its a noisy measurement, and after anally traveling shanks, I try to disturb the traveled shanks as little as possible. Plus the way I proceed SW provides no further useful info...see below for explanation of that. All I want is even hammer weight progression, which is not a noisy measurement, note to note

    I take a different attack towards action design. I have a set of regulation parameters, which, when setting up an action,  I always work to. I measure those parameters with the greatest precision I can muster, with dial indicators, etc. The parameters define my overall action leverage, so I establish them with anal precision. I use the same regulation parameters on each and every action, and thus the same leverage. If those parameter are not extant in the action, I impose them by adjusting geometry. Once my default parameters, and thus leverage are imposed, I am basically building the same action over and over again. So, its a known leverage, known general weight targets, and known overall inertia. Leading happens on the back half of the front lever, and kept to a minimum, with elevated DW starting in the 63-ish area to 50 at 88, and elevated BW in the mid 40's. I have been increasing frictions to the 12-15g area.  This only works if inertia is controlled, leverage slightly elevated, and lead used very sparingly. Once lead is in the keys, for whatever reason, including lower DW and BW's the feel of the action set up this way, takes a dive.

    By the way, with a controlled inertia action High DW and BW do not feel in the least heavy. They feel like you have an organic connection to the strike of the hammer. Fast play becomes easy and inuitive, without any feeling of runaway keys, as the elevated DW and decent friction keeps the keys completely under the finger's control. 



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


  • 5.  RE: Hammer weight curves

    Registered Piano Technician
    Posted 07-23-2021 07:24
      |   view attached
    Here is Jim Ialeggio's Hammer Wt data with Stanwood Hammer Weight zones overlaid.

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    David Stanwood
    Stanwood Piano Innovations Inc.
    West Tisbury MA
    508-693-1583
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    Original Message


  • 6.  RE: Hammer weight curves

    Registered Piano Technician
    Posted 07-22-2021 08:11
    The Stanwood  Hammer and Strike Weight "Curves"  are simply a frame of reference based on years of taking data on pianos.    Without them how would one qualify a hammer as being Light, Medium or Heavy?    Hammer and Strike Weight "Scales" are a different matter and alway apply to the situation at hand.   Your  working Hammer or Strike Weight scale may or may not match the "Curves" but sometimes can and do.

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    David Stanwood
    Stanwood Piano Innovations Inc.
    West Tisbury MA
    508-693-1583
    ------------------------------

    Original Message


  • 7.  RE: Hammer weight curves

    Registered Piano Technician
    Posted 07-22-2021 11:58
    I make that comment only because I see many people jumping through hoops to match the "scale" or SW or HW curve.  

    Other than the effect on tone (which is not a small consideration) light, medium or heavy only means something when considered in conjunction with the action ratio and if those SWs do or don't pair up with the action ratio appropriately.  Many people start the procedure of hammer replacement with a strike weight zone target and then adapt things from there.  I find that it actually makes more sense to start with a FW "zone" and then determine what type of strike weight you need to produce your target BW and then modify if the set or AR need to be reconsidered.  Albeit indirectly, the FW zone actually tells you more about the inertia that your combo will produce.  Given the same BW a lighter FW will be a lower inertia action than a high FW.  Not because of the FW but as an indication of the AR/SW relationship.  I realize you know this I'm just putting it out there.

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

    Original Message


  • 8.  RE: Hammer weight curves

    Registered Piano Technician
    Posted 07-23-2021 07:22
      |   view attached
    Here is David Love's Hammer Wt data with Stanwood Hammer Weight zones overlaid.

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    David Stanwood
    Stanwood Piano Innovations Inc.
    West Tisbury MA
    508-693-1583
    ------------------------------

    Original Message


  • 9.  RE: Hammer weight curves

    Registered Piano Technician
    Posted 07-23-2021 08:43
    I use an adjustable curve ruler to draw a curve on the smart chart which best represents what I want to achieve on any given set of hammers. Done after weighing samples in different sections and assessing how much needs to be done to achieve it. Rather than targeting a specific SW curve I aim for eveness. 

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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    Original Message


  • 10.  RE: Hammer weight curves

    Registered Piano Technician
    Posted 07-23-2021 09:07
    HI Peter,

    In recent years I've been changing over to the term "Scales" instead of "Curves" for Hammer/Strike Weight specifications because scale can cut across the zone curves or be straight as we are discussing.  The really great thing is that technicians are more generally paying attention to level and consistency of Hammer Weights.  It's a major foundation on tone and touch that's been overlooked in the big scheme of our industry, especially by Piano Makers.

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    David Stanwood
    Stanwood Piano Innovations Inc.
    West Tisbury MA
    508-693-1583
    ------------------------------

    Original Message


  • 11.  RE: Hammer weight curves

    Registered Piano Technician
    Posted 07-23-2021 11:56

    I agree with that approach and you can also do that without a smart chart by just entering the data of the prepped hammers into an excel spread sheet and then calculating a trend line as a 2nd or 3rd degree polynomial. (I generally use 2nd degree). In the curve I posted I then added .3 grams to the trend line calc so that I would be able to add weight and not have to further reduce any hammer. 

    I had already, by sampling, determined my targeted SW for the action (one that yields a FW of -85% of FW maximum) and used that as a guide in my hammer prep.   

    I don't really worry if the ends of the scale varies that much from the 85% target. I'm mostly concerned with the midrange of the piano, say, notes 16-64.  

    The goal is really to produce an action with a smooth inertia curve so that there's a uniform transition across the scale and the inertia is neither too high nor too low. The inertia will always be lower at the top of the piano given a uniform AR because there is less mass to move at the high end. 

    My curve cuts across the Stanwood scales but I don't consider that a problem or anything that needs to be rectified. My curve, in fact, is pretty much what the unaltered curve was out of the box with a natural drop at the bass/tenor break. I do smooth that transition



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

    Original Message


  • 12.  RE: Hammer weight curves

    Registered Piano Technician
    Posted 07-24-2021 16:43
    If you prefer the basic Stanwood style curves, rather than draw it out on a smart chart you can also calculate the curves this way.  The formulas on the chart are in the order, top to bottom, as the curves.  This is an easier way, I believe. 

    To translate this to an excel chart you would first create a column and number each cell down the column 1-88.  Next to it create a column for your SW.  If the row and column number for the number "1"  is, say, A10 (that would be the first column (A), Row 10, and you were looking for the top curve, you would type in the corresponding SW cell as follows:

    =-0.0008*A10^2-0.0277*A10+13.7

    then hit enter

    Then click on that cell and drag down all the way to note 88 and excel will auto fill for SW for each note.  Excel will automatically change each designated cell, A10, to the next cell, A11, A12, etc.  Since each of those cells is sequential, 1, 2, 3, 4, etc.  That will alter the formula for the corresponding cell for each note and give you a target for each note.  

    You can also do it as I showed earlier by simply plotting your existing HW or SW (I do what Jim does and plot and modify the HWs to get a smooth curve), and the create a trendline with it's own formula that that most closely resembles the existing set.  You'll end up with the least amount of modification required to get what you're after.  To see how my chart looks scroll down.




    Note number is self explanatory
    Measured hammer weight is my measuring on the scale of each individual hammer
    Hammer Weight Trendline is the calculated smooth curve from those hammers (2nd degree polynomial y=X^2+X+C)
    Change to the hammer weight whats required to achieve the trendline
    The box below "change HW by" is in the event I want to add some amount to the whole curve, say .2 grams.  See the chart below this one for an example. 
      
    Change HW by
    0
    Hammer Wt Trendline Final Hammer Weight Change to Hammer Weight Hammer Weight Note #
           
    10.7 10.7 -0.2 10.9 1
    10.6 10.6 -0.1 10.7 2
    10.5 10.5 0.1 10.4 3
    10.4 10.4 0.1 10.3 4
    10.4 10.4 0.0 10.4 5
    10.3 10.3 0.1 10.2 6
    10.2 10.2 0.0 10.2 7
    10.1 10.1 0.0 10.1 8
    10.0 10.0 0.1 9.9 9
    9.9 9.9 0.5 9.4 10
    9.8 9.8 0.6 9.2 11
    9.8 9.8 0.7 9.1 12
    9.7 9.7 0.3 9.4 13
    9.6 9.6 0.2 9.4 14
    9.5 9.5 0.0 9.5 15
    9.4 9.4 0.0 9.4 16
    9.3 9.3 -0.1 9.4 17
    9.3 9.3 -0.2 9.5 18
    9.2 9.2 -0.2 9.4 19
    9.1 9.1 0.0 9.1 20
    9.0 9.0 0.0 9.0 21
    8.9 8.9 -0.1 9.0 22
    8.9 8.9 -0.1 9.0 23
    8.8 8.8 -0.1 8.9 24
    8.7 8.7 -0.1 8.8 25
    8.6 8.6 -0.2 8.8 26
    8.5 8.5 0.4 8.1 27
    8.5 8.5 0.4 8.1 28
    8.4 8.4 0.3 8.1 29
    8.3 8.3 0.4 7.9 30
    8.2 8.2 0.3 7.9 31
    8.2 8.2 0.2 8.0 32
    8.1 8.1 0.1 8.0 33
    8.0 8.0 0.1 7.9 34
    7.9 7.9 0.0 7.9 35
    7.9 7.9 -0.1 8.0 36
    7.8 7.8 0.0 7.8 37
    7.7 7.7 -0.1 7.8 38
    7.6 7.6 0.0 7.6 39
    7.6 7.6 -0.2 7.8 40
    7.5 7.5 -0.2 7.7 41
    7.4 7.4 0.1 7.3 42
    7.3 7.3 0.0 7.3 43
    7.3 7.3 0.0 7.3 44
    7.2 7.2 0.0 7.2 45
    7.1 7.1 -0.1 7.2 46
    7.1 7.1 0.0 7.1 47
    7.0 7.0 -0.4 7.4 48
    6.9 6.9 -0.3 7.2 49
    6.8 6.8 0.1 6.7 50
    6.8 6.8 0.2 6.6 51
    6.7 6.7 0.1 6.6 52
    6.6 6.6 0.1 6.5 53
    6.6 6.6 0.1 6.5 54
    6.5 6.5 0.0 6.5 55
    6.4 6.4 0.2 6.2 56
    6.4 6.4 0.2 6.2 57
    6.3 6.3 -0.1 6.4 58
    6.2 6.2 -0.2 6.4 59
    6.2 6.2 -0.1 6.3 60
    6.1 6.1 0.0 6.1 61
    6.1 6.1 0.0 6.0 62
    6.0 6.0 0.1 5.9 63
    5.9 5.9 0.1 5.8 64
    5.9 5.9 0.1 5.8 65
    5.8 5.8 0.0 5.8 66
    5.7 5.7 0.0 5.7 67
    5.7 5.7 0.2 5.5 68
    5.6 5.6 0.1 5.5 69
    5.6 5.6 0.1 5.4 70
    5.5 5.5 0.1 5.4 71
    5.4 5.4 0.0 5.4 72
    5.4 5.4 0.1 5.3 73
    5.3 5.3 -0.1 5.4 74
    5.3 5.3 0.0 5.3 75
    5.2 5.2 0.0 5.2 76
    5.1 5.1 0.0 5.1 77
    5.1 5.1 0.1 5.0 78
    5.0 5.0 -0.1 5.1 79
    5.0 5.0 -0.1 5.1 80
    4.9 4.9 -0.1 5.0 81
    4.8 4.8 -0.2 5.0 82
    4.8 4.8 -0.1 4.9 83
    4.7 4.7 0.0 4.7 84
    4.7 4.7 0.1 4.6 85
    4.6 4.6 -0.1 4.7 86
    4.6 4.6 -0.2 4.8 87
    4.5 4.5 -0.3 4.8 88

    _______________________________________________________________________________


    Change Ham Wt by
    0.2
    Hammer Wt Trendline Final Hammer Weight Change to Hammer Weight Hammer Weight Note #
           
    10.7 10.9 0.0 10.9 1
    10.6 10.8 0.1 10.7 2
    10.5 10.7 0.3 10.4 3
    10.4 10.6 0.3 10.3 4
    10.4 10.6 0.2 10.4 5
    10.3 10.5 0.3 10.2 6
    10.2 10.4 0.2 10.2 7
    10.1 10.3 0.2 10.1 8
    10.0 10.2 0.3 9.9 9
    9.9 10.1 0.7 9.4 10
    9.8 10.0 0.8 9.2 11
    9.8 10.0 0.9 9.1 12
    9.7 9.9 0.5 9.4 13
    9.6 9.8 0.4 9.4 14
    9.5 9.7 0.2 9.5 15
    9.4 9.6 0.2 9.4 16
    9.3 9.5 0.1 9.4 17
    9.3 9.5 0.0 9.5 18
    9.2 9.4 0.0 9.4 19
    9.1 9.3 0.2 9.1 20
    9.0 9.2 0.2 9.0 21
    8.9 9.1 0.1 9.0 22
    8.9 9.1 0.1 9.0 23
    8.8 9.0 0.1 8.9 24
    8.7 8.9 0.1 8.8 25
    8.6 8.8 0.0 8.8 26
    8.5 8.7 0.6 8.1 27
    8.5 8.7 0.6 8.1 28
    8.4 8.6 0.5 8.1 29
    8.3 8.5 0.6 7.9 30
    8.2 8.4 0.5 7.9 31
    8.2 8.4 0.4 8.0 32
    8.1 8.3 0.3 8.0 33
    8.0 8.2 0.3 7.9 34
    7.9 8.1 0.2 7.9 35
    7.9 8.1 0.1 8.0 36
    7.8 8.0 0.2 7.8 37
    7.7 7.9 0.1 7.8 38
    7.6 7.8 0.2 7.6 39
    7.6 7.8 0.0 7.8 40
    7.5 7.7 0.0 7.7 41
    7.4 7.6 0.3 7.3 42
    7.3 7.5 0.2 7.3 43
    7.3 7.5 0.2 7.3 44
    7.2 7.4 0.2 7.2 45
    7.1 7.3 0.1 7.2 46
    7.1 7.3 0.2 7.1 47
    7.0 7.2 -0.2 7.4 48
    6.9 7.1 -0.1 7.2 49
    6.8 7.0 0.3 6.7 50
    6.8 7.0 0.4 6.6 51
    6.7 6.9 0.3 6.6 52
    6.6 6.8 0.3 6.5 53
    6.6 6.8 0.3 6.5 54
    6.5 6.7 0.2 6.5 55
    6.4 6.6 0.4 6.2 56
    6.4 6.6 0.4 6.2 57
    6.3 6.5 0.1 6.4 58
    6.2 6.4 0.0 6.4 59
    6.2 6.4 0.1 6.3 60
    6.1 6.3 0.2 6.1 61
    6.1 6.3 0.2 6.0 62
    6.0 6.2 0.3 5.9 63
    5.9 6.1 0.3 5.8 64
    5.9 6.1 0.3 5.8 65
    5.8 6.0 0.2 5.8 66
    5.7 5.9 0.2 5.7 67
    5.7 5.9 0.4 5.5 68
    5.6 5.8 0.3 5.5 69
    5.6 5.8 0.3 5.4 70
    5.5 5.7 0.3 5.4 71
    5.4 5.6 0.2 5.4 72
    5.4 5.6 0.3 5.3 73
    5.3 5.5 0.1 5.4 74
    5.3 5.5 0.2 5.3 75
    5.2 5.4 0.2 5.2 76
    5.1 5.3 0.2 5.1 77
    5.1 5.3 0.3 5.0 78
    5.0 5.2 0.1 5.1 79
    5.0 5.2 0.1 5.1 80
    4.9 5.1 0.1 5.0 81
    4.8 5.0 0.0 5.0 82
    4.8 5.0 0.1 4.9 83
    4.7 4.9 0.2 4.7 84
    4.7 4.9 0.3 4.6 85
    4.6 4.8 0.1 4.7 86
    4.6 4.8 0.0 4.8 87
    4.5 4.7 -0.1 4.8 88


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

    Original Message