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Probing for Touchweight Design Intent - 1977 Yamaha C3

  • 1.  Probing for Touchweight Design Intent - 1977 Yamaha C3

    Posted 03-22-2021 14:05
    I am studying a 1977 Yamaha C3 in our university collection which I believe has its original parts, and shows no evidence of modification, other than routine hammer reshaping.  The hammers appear to have lots of life left in them -- the piano has apparently seen light use.

    I am trying to get my head around the design intent in terms of how this action was originally set up.  Let me start with some observations.  My frame of reference is, for the most part, the manual from the Stanwood Touch Designer's Tool Kit.  I mention this so that it will be clear what I mean when I speak of strike ratio.  For any who are not familiar with this protocol, Strike Ratio is defined as (Balance Weight + Front Weight - Wippen Balance Weight) divided by Strike Weight. I am not dealing with radial arms ratio, mass action ratio, or the amount of hammer rise for 6 mm of key dip.

    There is a significant amount of lead in the keys.  Compared to what Stanwood identifies as a Front Weight Ceiling, values in the action are high.  Of the 18 samples measured , the trend line of the naturals starts at 1 gram below the ceiling at note 1, and rises to 5 grams above at note 88.  The trend line of the sharps starts at 5 grams above the ceiling, heads up a gram or two through the tenor section and then returns to 5 grams above the ceiling in the high treble.

    Strike ratio for the sharps is significantly higher than strike ratio for the naturals.  Naturals come in at an average of 5.8, and the sharps at 6.4.

    Strike weight trends at Stanwood 1/2 medium, rising to 3/4 medium in the high treble.  Hammers have been reshaped, but do not appear to be anywhere near end-of-life.  For what it's worth, I consider this a low weight range.

    Balance weight of the samples averages 34 grams.  The high is 38 and the low is 28. Downweight averages 43 grams.

    Projecting out from this data, I observe that in order to have balance weight in the 38 gram range, the original strike weight zone would have needed to be something like Stanwood 3/4 high, which would have hammer #1 weighing in at around 14.2 grams.  Does this make sense?  Did the 1977 C3's come with really heavy hammers?  Have these hammers been sanded down way more than I realize?

    What might have been the rationale for the big difference in strike ratio between the naturals and the sharps?  If you were doing a touchweight regulation on this piano, would you change this?  How else might you handle it?

    If I proceed to rework the touch weight on this piano, I am inclined to adjust strike weight upward to at least Stanwood 3/4 medium.  If I did this, left the action ratio alone, and shot for an average balance weight of 36 grams, my front weight for the sharps would sneak in at just under the Stanwood front weight ceiling, and my naturals would run at 7 or 8 grams below the ceiling.  That would produce a pretty low downweight in the naturals.

    On the other hand, if I changed the action ratio for the sharps, either by moving capstans or by cutting balance rail punchings, I could raise the balance weight for the naturals to what I would consider a more natural range.

    How would you approach this?








    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------


  • 2.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Registered Piano Technician
    Posted 03-23-2021 03:09
    It would be nice to see the entire survey and have some actual SW numbers but if you are wanting to raise the balance weight to 38 from 34 grams that means you will be removing, on average, 4 grams from the FW which would put the naturals more in the range of normal in terms of the FW maximums.  That they would hit the maximum at the top end of the piano is not as consequential as lower down since the inertia in the upper end is lower anyway due to lower strike weights (less hammer mass).  Remember that the lead itself is not the problem, it's the relationship between the SWR and the SW that is the problem and results in having a bit too much lead, in this case.  I think it's very unlikely that these hammers started out with a SW at #1 of 14+ grams.  That would be unusual.  

    How you approach this depends on how far you want to go with it.  Disparities between the sharps and the naturals are not unusual.  I would probably smooth the strike weights by reduction, meaning by taking some weight off each assembly even if it's fractional.  Survey the SWs and then run a trendline curve on Excel.  Select "show formula on the chart" when creating the trendline from the actual data you've input and then use that formula to set up a column that is your trendline smooth weight, rather than try and hit a Stanwood curve specifically.  Here's an Excel sample of what I do to create a trendline for hammer weights (in this case) with the formula displayed.  The turquoisish line is the actual measured weight, the black line overlay is the trendline and the formula displayed is for that trendline. (Ignore the labeling)  


    The spread sheet looks something like this.  (This is for hammer weight but you would do the same thing measuring the SW).  In excel you can add a cell that allows you to change the hammer weight by any amount.  It current reads zero but I often use a number like .1 or .2 or -.1 or -.2 so that I can see what gives me the least amount of alterations for each hammer (in this case).  The spread sheet below shows the measured hammer weight, the calculated hammer weight trendline from the formula, the change that needs to be made to each hammer to achieve that and the final weight (which in this case matches the trendline).

    Change Ham Wt by
    0
    Hammer Trendline Final Hammer Weight Change to Hammer Weight Hammer Weight Measured Note #
           
    9.1 9.1 0.0 9.1 1
    9.0 9.0 -0.1 9.1 2
    9.0 9.0 0.1 8.9 3
    8.9 8.9 0.2 8.7 4
    8.9 8.9 0.2 8.7 5
    8.8 8.8 0.1 8.7 6
    8.8 8.8 0.0 8.8 7
    8.8 8.8 0.0 8.8 8
    8.8 8.8 0.0 8.8 9
    8.7 8.7 0.0 8.7 10
    8.7 8.7 0.0 8.7 11
    8.7 8.7 0.0 8.7 12
    8.7 8.7 0.0 8.7 13
    8.7 8.7 0.0 8.7 14
    8.6 8.6 0.1 8.5 15
    8.6 8.6 0.0 8.6 16
    8.6 8.6 0.0 8.6 17
    8.6 8.6 0.1 8.5 18
    8.5 8.5 0.0 8.5 19
    8.5 8.5 0.0 8.5 20
    8.5 8.5 -0.2 8.7 21
    8.5 8.5 -0.1 8.6 22
    8.4 8.4 -0.2 8.6 23
    8.4 8.4 0.0 8.4 24
    8.4 8.4 0.1 8.3 25
    8.3 8.3 -0.1 8.4 26
    8.3 8.3 0.1 8.2 27
    8.3 8.3 -0.1 8.4 28
    8.2 8.2 0.4 7.8 29
    8.2 8.2 -0.1 8.3 30
    8.2 8.2 0.0 8.2 31
    8.1 8.1 0.0 8.1 32
    8.1 8.1 0.2 7.9 33
    8.0 8.0 0.1 7.9 34
    8.0 8.0 0.1 7.9 35
    8.0 8.0 0.3 7.7 36
    7.9 7.9 0.2 7.7 37
    7.9 7.9 0.2 7.7 38
    7.8 7.8 0.2 7.6 39
    7.8 7.8 0.2 7.6 40
    7.7 7.7 0.2 7.5 41
    7.7 7.7 0.2 7.5 42
    7.6 7.6 0.2 7.4 43
    7.6 7.6 0.3 7.3 44
    7.5 7.5 0.2 7.3 45
    7.5 7.5 0.1 7.4 46
    7.4 7.4 -0.1 7.5 47
    7.4 7.4 -0.2 7.6 48
    7.3 7.3 -0.3 7.6 49
    7.3 7.3 -0.3 7.6 50
    7.2 7.2 -0.3 7.5 51
    7.1 7.1 0.0 7.1 52
    7.1 7.1 0.1 7.0 53
    7.0 7.0 -0.1 7.1 54
    7.0 7.0 0.0 7.0 55
    6.9 6.9 0.1 6.8 56
    6.8 6.8 0.0 6.8 57
    6.8 6.8 0.0 6.8 58
    6.7 6.7 -0.1 6.8 59
    6.6 6.6 -0.2 6.8 60
    6.6 6.6 0.0 6.6 61
    6.5 6.5 0.0 6.5 62
    6.4 6.4 -0.2 6.6 63
    6.4 6.4 -0.1 6.5 64
    6.3 6.3 -0.1 6.4 65
    6.2 6.2 0.0 6.2 66
    6.1 6.1 0.0 6.1 67
    6.1 6.1 0.1 6.0 68
    6.0 6.0 0.1 5.9 69
    5.9 5.9 0.1 5.8 70
    5.8 5.8 0.2 5.6 71
    5.8 5.8 0.0 5.8 72
    5.7 5.7 0.1 5.6 73
    5.6 5.6 0.1 5.5 74
    5.5 5.5 0.1 5.4 75
    5.4 5.4 0.0 5.4 76
    5.4 5.4 0.1 5.3 77
    5.3 5.3 0.1 5.2 78
    5.2 5.2 0.1 5.1 79
    5.1 5.1 0.1 5.0 80
    5.0 5.0 0.1 4.9 81
    4.9 4.9 0.1 4.8 82
    4.8 4.8 0.1 4.7 83
    4.7 4.7 0.0 4.7 84
    4.7 4.7 0.1 4.6 85
    4.6 4.6 0.2 4.4 86
    4.5 4.5 0.3 4.2 87
    4.4 4.4 0.4 4.0 88
     
    I would then smooth the curve by shaving off the high spots and wouldn't make any changes unless it was .2 grams or more.  You can reduce SW with a sharp plane and dragging the hammer across it to remove easily up to about .3 grams.

    I would then shim the balance rail punching (a thin strip of veneer under the back of the BR punching) for the sharps only.  Then survey the BW for the entire action and remove 1 gram of FW for each 1 gram of increase you want in the BW on each note.  Pretty straight forward.  You should end up with a FW of 3+ grams or so under the max in the bass and around the maximum in the high treble.  With a shim under the balance rail punching on the sharps you will reduce the SWR and probably end up with a FW that is more in compliance for a 38g BW. 



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



  • 3.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Posted 03-23-2021 13:20
    Thank you so much, David, for your detailed and most helpful response!  It does give me some very useful perspective on this project.

    First, I'll give you the specific data, which you suggested would be helpful:







    I've crunched the numbers some more and have been fascinated to see that if I use the values of the trend line for the existing samples as my strike weight targets, I will indeed end up within .2 grams of the target that would be identified by calculating from a front weight of Stanwood Ceiling -3 grams, a balance weight of 38 grams, and an overall strike ratio of 5.8.  And yes, the front weight would climb a little closer to the ceiling in the treble.

    Thanks as well for the suggestion of the veneer shim behind the balance rail pins.  That option makes a lot of sense in this situation.

    When it comes to modifying strike weight, I am equally comfortable with subtracting and adding mass, and with the existing scatter in the samples I anticipate I may be doing some of both.

    I am enjoying this project, and very much appreciate your input.

    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------



  • 4.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Registered Piano Technician
    Posted 03-23-2021 13:41
    One thing it certainly tells you, factory weigh offs are pretty random.  Let me look this over and I'll get back to you.

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



  • 5.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Registered Piano Technician
    Posted 03-24-2021 02:16
    So as I see it, the main problem is that the SWR is too high for the SW curve, or vice versa.  That's causing an excess of FW and the excess FW is an indication that the SWR/SW relationship is bad.  That combination, in this case, creates high inertia in the action and especially in the bass.  My ideal target is to get a medium BW (37) with 80-85% of front weight maximum--though I allow that to deviate in the upper part of the piano without worry.  You can't achieve that with this action the way it's set up.  The options are to either reduce the SWs substantially which is difficult because the hammers are already glued on the shanks.  Or you can reduce the SWR to better accommodate the current SW curve with smoothing.  You will especially need to reduce the SW in the bass section. 

    The difference between the sharps and naturals is driven by the difference in KR, .53 and .51 respectively.  That's a harder fix.  I'm not sure I would take the trouble to create two capstan lines but you could.  If the action were in my shop I think I'd probably leave well enough alone there and do the following.

    Install a shim behind the balance rail pin on both the sharps and naturals.  (see picture below, you may have to enlarge).  The shim is cut from 1 mm thick veneer in 1/8" strips and tacked in place under the back of the balance rail punching.  This moves the fulcrum point back a bit and will drop the SWR.  I prefer this over the cut punching method.  You may have to either relevel the keys or at least dip them again as this will raise the front of the key by 2 mm.  You can also replace the BR punching with something thinner if you want to compensate that way.  Lowering the SWR will require more key dip either way. 

     
    Next I would try to hit this SW curve (see below) which uses your trendline formula based on your samples.  The most material will need to be taken from the bass section, it appears.  But based on the samples you have the rest is doable.  I use a plane held in a bench vise to shave material from the side of the hammer.  Take more from the fat part of the hammer (the felt) and don't thin the tails too much.  You don't gain much there anyway.  Though the photo shows me using my hand to push it through i actually use a dowel with a notch cut in it to keep my hands away from the blade.


    After that I'd just do a complete UW and DW survey and determine the balance weight on each note and then modify the FWs to hit your new BW target 38 grams is fine.  If you're feeling adventurous you could try and calculate the FW specs but I think the shim will complicate that.  

    Here's the suggested strike weight curve using the set of hammers that are on there.  The other alternative is to replace the hammers with a lighter weight hammer that's more in line with the existing SWR but you mentioned that the hammers seem fine and then you'll have to decide if a lighter weight hammer is appropriate tonally for this piano.  With an 11.3 gram SW at note #1 the hammer weight is probably around 9.6 grams.  If you did nothing else you'd probably have to drop the hammer weight by at least 1 gram there to achieve your BW target with a reasonable FW.  

    SW Trendline Calculation Final SW (-.2g) Note #
           
    11.5 11.3     1
    11.5 11.3     2
    11.5 11.3     3
    11.4 11.2     4
    11.4 11.2     5
    11.3 11.1     6
    11.3 11.1     7
    11.3 11.1     8
    11.2 11.0     9
    11.2 11.0     10
    11.1 10.9     11
    11.1 10.9     12
    11.1 10.9     13
    11.0 10.8     14
    11.0 10.8     15
    10.9 10.7     16
    10.9 10.7     17
    10.8 10.6     18
    10.8 10.6     19
    10.7 10.5     20
    10.7 10.5     21
    10.6 10.4     22
    10.6 10.4     23
    10.5 10.3     24
    10.5 10.3     25
    10.4 10.2     26
    10.4 10.2     27
    10.3 10.1     28
    10.3 10.1     29
    10.2 10.0     30
    10.1 9.9     31
    10.1 9.9     32
    10.0 9.8     33
    10.0 9.8     34
    9.9 9.7     35
    9.8 9.6     36
    9.8 9.6     37
    9.7 9.5     38
    9.6 9.4     39
    9.6 9.4     40
    9.5 9.3     41
    9.4 9.2     42
    9.4 9.2     43
    9.3 9.1     44
    9.2 9.0     45
    9.2 9.0     46
    9.1 8.9     47
    9.0 8.8     48
    9.0 8.8     49
    8.9 8.7     50
    8.8 8.6     51
    8.7 8.5     52
    8.7 8.5     53
    8.6 8.4     54
    8.5 8.3     55
    8.4 8.2     56
    8.3 8.1     57
    8.3 8.1     58
    8.2 8.0     59
    8.1 7.9     60
    8.0 7.8     61
    7.9 7.7     62
    7.9 7.7     63
    7.8 7.6     64
    7.7 7.5     65
    7.6 7.4     66
    7.5 7.3     67
    7.4 7.2     68
    7.3 7.1     69
    7.3 7.1     70
    7.2 7.0     71
    7.1 6.9     72
    7.0 6.8     73
    6.9 6.7     74
    6.8 6.6     75
    6.7 6.5     76
    6.6 6.4     77
    6.5 6.3     78
    6.4 6.2     79
    6.3 6.1     80
    6.2 6.0     81
    6.1 5.9     82
    6.0 5.8     83
    5.9 5.7     84
    5.8 5.6     85
    5.7 5.5     86
    5.6 5.4     87
    5.5 5.3     88

    That's my take on it anyway.





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



  • 6.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Registered Piano Technician
    Posted 03-24-2021 11:43
    The other thing you could do, of course, is just move the capstan for everything, smooth the strike weights as above and the reset the BW.  You probably need to move it about 3 mm and you might have to add a strip of felt to the wippen heal to protect the capstan from contacting the wooden edge of the heal.  You'd still have the sharp/natural disparity but it would be better than the way it is now.

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



  • 7.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Posted 03-24-2021 12:36
      |   view attached
    Thank you again, David, for your detailed response.

    It seems what we're seeing is pushing us in different directions at this point, and I'm trying to figure out where our premises are diverging.

    We share the understanding that FW is excessive.  We also share the understanding that the SWR of the sharps is too high for the SW curve.  It appears that we differ on the appropriateness of the SWR for the naturals.  I am inclined not to shim the naturals at the balance rail.

    I am attaching an Excel spreadsheet in which I am testing various options for BW, % of FW Ceiling, and SR.  There's a screen shot below, but the attachment should be downloadable, and in it, various figures can be plugged in in the first row and the figures in the columns will adjust.  The sheet is set up using Stanwood's equation of balance.

    FW is currently excessive, but BW is trending low.  If I work with the existing SWR for the naturals, which is 5.8, and choose a BW of 37g and a FW of 85% of Stanwood's FW Ceiling, target strike weights in the bass appear higher than existing trend line values.  I am more inclined to add weight there than to remove it.  Working with a strike weight tolerance of .2g, note 49 is the lowest note that requires weight reduction, using the existing trend line as the starting point.  Tapering the FW up to the the ceiling value at note 67 results in the SW target and the existing SW trend line converging at that point.  If I allow BW to climb in the treble up to 6 grams at note 88 (43g BW), I again have a convergence of my SW target and the existing trend line. 

    I certainly have room to remove some weight, so hitting the FW ceiling that early and increasing the BW that much will not be necessary, but the existing SR of the naturals seems to give me a reasonable amount of flexibility.

    I haven't yet tested out the effect of shimming the balance rail for the sharps, but I'm expecting it to change the KR and the SR sufficiently to give me an appropriate amount of compatibility with the naturals.

    This plan of action differs from your suggestion.  What am I failing to take into account?






    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------

    Attachment(s)

    xlsx
    Mar 24.xlsx   21 KB 1 version


  • 8.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Registered Piano Technician
    Posted 03-25-2021 02:21
    Hi Floyd

    I don't think you're missing anything.  The plan to just lower the SWR on the sharps and leave the naturals alone is fine.  At least that would make them a little closer to the naturals even if you don't quite get them exactly the same.  I don't think a shim on the sharps alone will get you to exactly the same SWR as the naturals but it will lower it some.  As I looked more carefully at the data you posted it seemed to suggest that at 37 or 38 BW you would still be a little on the high side with respect to FW, though it's not that bad as I do the complete chart (see below).  So in general I thought that lowering the SWR through the keyboard would be ok.  The FW maximum is, of course, a somewhat artificial ceiling.  There's nothing that says that once you cross that line that you suddenly get into trouble.  The FW max is just an indication that you are approaching an area where the SW and SWR are not quite compatible.  Since inertia derives mostly from the relationship between SW and SWR, and FW is an indicator of when you are trending too high, then it's best to try and target something below that.  The action will perform better.  

    A SWR of 5.8 - 6.2 is pretty typical of original Steinway actions (early 1900s)--I realize this is a Yamaha so just for purposes of high SWR examples.  But the SWs tended to be very low and the FWs were more in the 75% of max range.   A strike weight of around 8.5 at note 40 on those pianos is not unusual.  Yours is a full gram above that.  So it occurred to me that lowering everything with the balance rail shim would have some advantages even though you would be left with the disparity between the sharps and the naturals.  I suppose going for uniformity even if the FWs are a bit high argues for just changing just the sharps.  I would still try and remove some weight from the bass hammers as they seem quite a bit higher than the tenor section.  Note #16 is troubling and hopefully not an indication of the notes around it or you'll be carving a bit of weight off that section.

    I think if you use the existing SW curve based on your trendline formula (without the .2g reduction) and put a shim just on the sharps your action will look something like this at a 37g BW (unless I made an error somewhere).  If you go to 38 you'll drop the FW by another gram.  

    16.7 Wippen SW
    37 BW Target 
    0.51 KR Nats   KR Sharps 0.52
    5.80 SWR Nats   SWR Sharps 6.10
    Note SWR FW KR Bal SW 
      (From Worksheet) FW max
       
    1 5.80 38.4 0.51 37 11.5 41.3 93%
    2 6.10 41.8 0.52 37 11.5 41.1 102%
    3 5.80 38.0 0.51 37 11.5 40.8 93%
    4 5.80 37.7 0.51 37 11.4 40.6 93%
    5 6.10 41.1 0.52 37 11.4 40.3 102%
    6 5.80 37.3 0.51 37 11.3 40.1 93%
    7 6.10 40.6 0.52 37 11.3 39.8 102%
    8 5.80 36.9 0.51 37 11.3 39.5 93%
    9 5.80 36.6 0.51 37 11.2 39.3 93%
    10 6.10 39.9 0.52 37 11.2 39.0 102%
    11 5.80 36.1 0.51 37 11.1 38.8 93%
    12 6.10 39.4 0.52 37 11.1 38.5 102%
    13 5.80 35.6 0.51 37 11.1 38.3 93%
    14 6.10 38.9 0.52 37 11.0 38.0 102%
    15 5.80 35.1 0.51 37 11.0 37.8 93%
    16 5.80 34.9 0.51 37 10.9 37.5 93%
    17 6.10 38.0 0.52 37 10.9 37.2 102%
    18 5.80 34.3 0.51 37 10.8 37.0 93%
    19 6.10 37.4 0.52 37 10.8 36.7 102%
    20 5.80 33.7 0.51 37 10.7 36.4 93%
    21 5.80 33.5 0.51 37 10.7 36.1 93%
    22 6.10 36.5 0.52 37 10.6 35.8 102%
    23 5.80 32.9 0.51 37 10.6 35.5 93%
    24 6.10 35.9 0.52 37 10.5 35.2 102%
    25 5.80 32.3 0.51 37 10.5 34.9 92%
    26 6.10 35.2 0.52 37 10.4 34.6 102%
    27 5.80 31.6 0.51 37 10.4 34.3 92%
    28 5.80 31.3 0.51 37 10.3 34.0 92%
    29 6.10 34.2 0.52 37 10.3 33.7 102%
    30 5.80 30.6 0.51 37 10.2 33.3 92%
    31 6.10 33.5 0.52 37 10.1 33.0 102%
    32 5.80 30.0 0.51 37 10.1 32.7 92%
    33 5.80 29.6 0.51 37 10.0 32.4 91%
    34 6.10 32.4 0.52 37 10.0 32.1 101%
    35 5.80 28.9 0.51 37 9.9 31.7 91%
    36 6.10 31.7 0.52 37 9.8 31.4 101%
    37 5.80 28.2 0.51 37 9.8 31.0 91%
    38 6.10 30.9 0.52 37 9.7 30.7 101%
    39 5.80 27.5 0.51 37 9.6 30.4 90%
    40 5.80 27.1 0.51 37 9.6 30.0 90%
    41 6.10 29.7 0.52 37 9.5 29.6 100%
    42 5.80 26.3 0.51 37 9.4 29.3 90%
    43 6.10 28.9 0.52 37 9.4 28.9 100%
    44 5.80 25.5 0.51 37 9.3 28.5 90%
    45 5.80 25.1 0.51 37 9.2 28.1 89%
    46 6.10 27.6 0.52 37 9.2 27.7 100%
    47 5.80 24.3 0.51 37 9.1 27.3 89%
    48 6.10 26.8 0.52 37 9.0 26.9 99%
    49 5.80 23.5 0.51 37 9.0 26.4 89%
    50 6.10 25.9 0.52 37 8.9 26.0 100%
    51 5.80 22.6 0.51 37 8.8 25.6 88%
    52 5.80 22.2 0.51 37 8.7 25.1 88%
    53 6.10 24.5 0.52 37 8.7 24.7 99%
    54 5.80 21.3 0.51 37 8.6 24.2 88%
    55 6.10 23.6 0.52 37 8.5 23.8 99%
    56 5.80 20.4 0.51 37 8.4 23.3 88%
    57 5.80 19.9 0.51 37 8.3 22.8 87%
    58 6.10 22.1 0.52 37 8.3 22.3 99%
    59 5.80 19.0 0.51 37 8.2 21.8 87%
    60 6.10 21.1 0.52 37 8.1 21.3 99%
    61 5.80 18.1 0.51 37 8.0 20.8 87%
    62 6.10 20.1 0.52 37 7.9 20.2 100%
    63 5.80 17.1 0.51 37 7.9 19.7 87%
    64 5.80 16.6 0.51 37 7.8 19.1 87%
    65 6.10 18.6 0.52 37 7.7 18.6 100%
    66 5.80 15.6 0.51 37 7.6 18.0 87%
    67 6.10 17.5 0.52 37 7.5 17.4 101%
    68 5.80 14.6 0.51 37 7.4 16.8 87%
    69 5.80 14.1 0.51 37 7.3 16.2 87%
    70 6.10 15.9 0.52 37 7.3 15.5 103%
    71 5.80 13.1 0.51 37 7.2 14.9 88%
    72 6.10 14.8 0.52 37 7.1 14.3 104%
    73 5.80 12.0 0.51 37 7.0 13.6 88%
    74 6.10 13.7 0.52 37 6.9 13.0 105%
    75 5.80 10.9 0.51 37 6.8 12.3 89%
    76 5.80 10.4 0.51 37 6.7 11.6 90%
    77 6.10 12.0 0.52 37 6.6 11.0 109%
    78 5.80 9.3 0.51 37 6.5 10.3 90%
    79 6.10 10.8 0.52 37 6.4 9.6 113%
    80 5.80 8.2 0.51 37 6.3 9.0 91%
    81 5.80 7.6 0.51 37 6.2 8.3 92%
    82 6.10 9.0 0.52 37 6.1 7.6 119%
    83 5.80 6.4 0.51 37 6.0 7.0 92%
    84 6.10 7.8 0.52 37 5.9 6.3 124%
    85 5.80 5.3 0.51 37 5.8 5.6 94%
    86 6.10 6.6 0.52 37 5.7 5.0 131%
    87 5.80 4.1 0.51 37 5.6 4.3 95%
    88 5.80 3.5 0.51 37 5.5 3.7 94%



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



  • 9.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Posted 03-25-2021 11:48
    Hi David,

    Thank you again for your willingness to engage at length with me on this project.  I could have "proceeded as usual" with this piano, but the presence of what appeared to be the original configuration struck me as an opportunity to ask questions I had not previously explored.  You have provided for me a perspective with which I can constructively interact.  I consider that valuable.

    Let me further say that I note with admiration the contributions you make to this community on an ongoing basis.  You have interacted deeply with various fields of knowledge that fall within our profession as piano technicians, and have been generous in sharing the results of that exploration and learning. I am very aware that we are all beneficiaries of the movement away from the mindset of guarding proprietary knowledge that  I understand once characterized our profession.

    I wish access to the archives of these forums was more transparent.  There are information pieces that you have posted here that have enduring value.  I have a few of them printed out and sitting in binders, and a few more that I have included in an index I've been building with links to postings I want to be able to access in the future.  Your contributions really are making us better technicians.

    I am honored by your willingness to interact so freely and thoroughly with me.  I very much appreciate your kindness.

    Sincerely,
    Floyd


    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------



  • 10.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Registered Piano Technician
    Posted 03-25-2021 21:48

    Floyd

    Thanks so much for your kind words. There's no question that I have benefited from other's willingness to share information with me.  In a trade such as ours I think it's very important to engage in this kind of exchange, and thankfully, mostly people do. It benefits us all-even, maybe especially, when we disagree.  It's part of what the trade needs to keep growing. I'm glad to pay it forward and hope that what I have offered over the years has been helpful. My career is slowly winding down (though I ain't done yet) and so hanging onto "proprietary" information means a lot less than it once might have. 

    On this project I just want to comment that I'm glad to see more and more people using spreadsheets to analyze data whether it be action design issues or soundboard design. Action issues present problems that are addressed very well by a spreadsheet approach. It allows one to visualize exactly what's going on and see how various solutions play out. These types of problems I find very compelling and interesting to try and solve. I'll be curious to know the outcome on this one. 

    Thanks and stay safe. 



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



  • 11.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Posted 03-26-2021 16:51
      |   view attached
    Looks like I made some data entry errors on my spreadsheet.  I pasted in the Key Ratio where I should have entered the Wippen Balance Weight, and in the equation for the existing hammer trend line added an extra 0 after the decimal in the x value.  I'm attaching the corrected downloadable spreadsheet.  I see better now the significance of some of your comments above.



    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------

    Attachment(s)

    xlsx
    Mar 25.xlsx   21 KB 1 version


  • 12.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Posted 03-26-2021 19:39
    I'm moving toward choosing a plan of action.  I have come up with four options.  In every case I would shim the sharps at the balance rail to bring the strike ratio closer to the naturals:

    1.  Work from a front weight of 85% of ceiling, and a balance weight of 3.8 grams.  Remove weight from hammers 1 to 33, a maximum of 4 grams necessary as compared to the trendline.  Advantage:  This plan follows the existing trend line very closely from note 33 up.  Disadvantage:  This involves removing weight from older hammers that have already seen some filing.  Movement is apparently in the a direction away from the design intent.  Not that the design intent is particularly clear, given the amount of weight in the keys.

    2.  Use the existing strike weight trend line for my spec, with a 38 gram balance weight.  Resulting front weight will range between 90% of ceiling in the bass and 67% of ceiling in the treble (though in the treble that amounts to 1.2 g of front weight). Advantage: This option probably represents the smallest change from the current set-up.  Disadvantage: This approach serves to normalize a weight spec that is a result of at least a few hammer filings, however modest.  Not as big a move away from the original as option 1, but still in the same direction.

    3.  Use Stanwood Strike Weight Curve 8 for my hammer spec, and 3.8 grams for my balance weight spec.  This will involve raising strike weight above the existing trend line in hammers 1 to 66 to the level of 4 grams above the trend line in the heaviest hammers.  Resulting Front Weight will average 92% of the Front Weight Ceiling.  Advantages: I expect this hammer weight zone to be easily repeatable when new hammers are needed.  This involves a little less FW reduction than the first two options.  The change in Strike Weight reverses, in direction at least, the effects of hammer filings to date.  Disadvantage: This is a higher inertia scenario than the first two options, though not necessarily problematically so.


    4.  Set the Front Weight to the ceiling spec.  Use the Stanwood 8  strike weight spec.  Balance weight will fall in at about 36.5 grams.  Or use the existing strike weight trend line as my spec.  Balance weight will fall in at 34.6 grams. Rationale: I am working in a university environment, and would like to engage students and faculty in conversation toward a growing awareness of the options available in touch weight.  It is easy to give piano users an experience of excessively heavy touch weight by adding binder clips to a well balanced action.  This would give me an instrument with which to demonstrate an intentionally lighter touch touch weight scenario.  Binder clips could be used to achieve a more normal set-up for routine use, but removed for demonstration purposes.  Reduction of FW for a normal setup could easily be done at a future time, if "demonstration model mode" outlives its usefulness.


    I'm actually leaning toward option 4 with the 34.6 gram balance weight.  What do you think?


    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------



  • 13.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Registered Piano Technician
    Posted 03-27-2021 02:23
    I don't like option #4.  Why would you opt to set the FW at the max and take a relatively light BW?  Given the choice of a higher BW and a lower FW or a lower BW and a FW at maximum I would choose the former without question.  Also, a 37 or 38g BW is very medium weight and even slightly light by some current standards.  Setting a 34 gram BW (which is a very light action in my book) means that you will likely barely have adequate UW in the lower part of the piano (min 20 grams) and might not even have that.  Adequate UW is important.  

    If it were me, I would first shim the sharps at the balance rail to reduce that SWR to wherever it ends up. 

    Then survey and plot all the current SWs.  Calculate a trendline and smooth the SW curve with the least amount of manipulation possible on each hammer assembly.  Play with the trendline curve by adding .1, .2g, or subtracting the same amount, until you get the curve that requires the fewest changes possible and no changes that require more then a .2 gram reduction in weight on any one note.  Taking off .2 or .3 grams is easy--a few swipes across a sharp plane.  More than that starts to get more difficult.  I would try not to increase the SWs above the trendline curve as you are already on the high side for this action.  I would not try to hit a specific Stanwood Zone.  it's not necessary and probably not applicable to this situation.  

    After that I would survey the BW for all notes (UW+DW)/2, and then alter the front weights to achieve a uniform BW.  If the FW goes above 100% in the upper treble don't worry about it.  It's not that important up there.  The inertia will still be lower than the lower notes because the hammer mass is less.  

    The argument for setting a uniform BW over a smooth FW  (if you have to choose) is that the BW, when converted to DW, represents the minimum force required to actuate the key.  Most complaints about uniformity of the action (assuming it's not a friction problem) occur when pianists are trying to play at the pianissimo level not at the forte level.  Since pianissimo represents, basically, the minimum force required to actuate the key, having a uniform BW will give you evenness where it counts; at the pianissimo level.  Some unevenness in the FW will not be perceived by the pianist in this case.  A precisely smooth FW curve is a vanity issue mostly.  If there are slight variations in the FW curve but a smooth SW curve and uniform BW the pianist will be happy.  A slightly bumpy FW curve will not impact their perception of evenness.  Remember, pianists want predictability.  The want to know that when they go to press a key it will respond in the manner they anticipate (same is true of voicing).  At the pianissimo level, uniform BW is more important than a smooth FW curve in terms of predictability.   From your initial survey your FWs will mostly be under or near the max.  A few will be over.  I think that's ok in this situation.   

    So, after the BW survey I would simply make the BWs even and let the FWs fall where they will and accept that you have different SWRs on the naturals and sharps.  The varied length of those keys creates differences anyway that probably trump (gosh I hate using that word anymore) any slight differences in SWR.  The relationship of FW to BW is 1:1, they are inversely proportional.  Add 1 gram of FW to reduce the BW by 1 gram. 

    PS  Just as an aside, it's interesting that we spend some much time worrying about absolute uniformity as measured from the end of the key.  Pianists, of course, don't always play the keys from the tip where we measure the UW and DW.  They play all over the keys.  If the DW is 50 g at the tip and the pianist plays that key near the fallboard or ~half way to the balance rail, the DW at that point will be 100g.  Yet the pianist doesn't notice that the key is twice as hard to depress, they just play.  It's the marvel of the human brain that we can account for that and instantly adapt and not have it get in the way of our performance or our perception.  Moreover, when we go through a series of, say, two handed chords in which the fingers are interacting with the keys in all kinds of different positions on the key, and with each different position creating a different DW between each finger, we still remark, after an action has been balanced properly, about how even it is.  In reality, it is anything but!  However, in this case, it can be uneven but still be predictable, and that's what counts.

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



  • 14.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Posted 03-29-2021 18:01
      |   view attached
    Thanks again, David, for your feedback.  I've done a full survey of the existing strikeweight.  I've included lines for a .2 gram tolerence in the graph:

    There is enough weight to be removed on a couple of these notes that I'm inclined to use my trendline as my target, even though it means adding weight to a few more hammers than if I dropped my target a bit.  I've succeeded in pulling down hammer 7 by .5 grams, but it would take another .7 grams (assuming I achieved an AR of 5.8) to hit 85% of FW.  I don't think I'm going to get there.

    Thank you as well for again clearly articulating your argument for consistent balance weight as opposed to  smooth front weight, if such a choice needs to be made.  I look forward to seeing the results of a weigh-off after I've shimmed the balance rail.  It will be interesting to see what options present themselves.

    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------

    Attachment(s)

    xlsx
    Starting SW.xlsx   17 KB 1 version


  • 15.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Registered Piano Technician
    Posted 03-29-2021 20:13
    Yes I don't think you should try to get to 85% on this action. Not unless you want to set the BW at 40g or higher.  Just set the SW curve as low as is easily achievable based on the trend line even if some will have to come up a little in weight. Shim the balance rail for the sharps and then balance the action at 38g or whatever and take what you get on the FWs. It will be an improvement.

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



  • 16.  RE: Probing for Touchweight Design Intent - 1977 Yamaha C3

    Posted 04-05-2021 17:10
      |   view attached
    I shimmed the sharps at the balance rail with veneer, placing the strip just behind the balance rail pins, and adjusted the strike weight to the trend line of hammer weights as I found them.  I then weighed off the keyboard, and made a projection of what the new front weight would be if I adjusted the balance weight to 38 grams.  As seen in the graph below, the Front Weight of all but 6 keys falls within 2 grams of the trend line of the set of Front Weight values identified.  Jim Ialeggio, in responding to a question oposed by me in an earlier thread, stated that he's seen some consensus around the notion that a margin of error of 2 grams is reasonable.  I see Nick Gravagne citing Baldassin and Teel in speaking of the same figure.  That suggests to me that the values here are in a narrow enough range that I can favor either consistent Balance Weight, or consistent Front Weight, and the "unfavored" spec will be within reasonable bounds, so long as I do some appropriate compromising with the handful of outliers.

    Thank you again, David, for suggesting the veneer shim at the balance rail.  I'm very pleased with the results.



    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------

    Attachment(s)

    xlsx
    Apr5.xlsx   16 KB 1 version