<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 12 (filtered medium)"><style></style></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1>David S.:<o:p></o:p><o:p> </o:p>Here are some data worth looking at, perhaps.  The top lines are measurements taken on my action model (Renner) using your system and the bottom in color is my system of measuring the lever.  As you can see the results are very close.  When adding some strike weight to the hammer, in this case 2.2 grams, the balance weight changed at a ratio of 5.68 ((83.5-71)/2.2 ). Pretty close considering the potential for measurement error with measuring upweight and downweight.  But at least as I measure it, it doesn’t agree with the SWR exactly, or my distance ratio for that matter (though that one appears to be a bit closer). Measurement protocols are clearly a factor.<o:p></o:p><o:p> </o:p>Which, for me, is really the issue.  On this model I’ve taken great pains to ensure that each measurement is very accurate, having taken it several times.  Even so, there is even a discrepancy between the two SWR measurements with different strikeweights.  Yes, of course you can take an average but when I’ve had individuals send me data in order to help them with weight problems I’ve found that the SWRs are all over the place with quite a wide range.   Totally unreliable may have been a bit strong, but I have found it certainly much less reliable (and more time consuming) than the distance method.  Some  of that may indeed be because of non straight balance rail lines or capstan placement, knuckle placement etc.  However, much of it, I’m convinced, is due to the difficulty in the protocols for measuring upweight and downweight.  Just how fast should the movement of the hammer be, how far should it travel, should the upstroke be the same speed as the downstroke, faster, slower?  If I’m asking these questions you can be sure that different people are taking measurements in different ways yielding unpredictable results.  <o:p></o:p><o:p> </o:p>Distance and weight ratios may be different as you are looking at them, I don’t know.  I’d be interested to hear the specifics. Typically they are referred to as distance and force ratios and there is definitely a relationship as far as I understand it.  The force leverage is calculated as 1 divided by the distance ratio and predicts how much weight is required to balance a hammer of x grams.  So in the example below (mine) the 5.78 DR would yield a FR of .17 which means that an 8.7 strike weight will balance at 50 grams at the key (8.7/50 = .17.)  I would be interested to hear the argument for gravity vectors impacting this, it’s clearly outside the range of my engineering chops.  <o:p></o:p><o:p> </o:p>However, if the issue is predicting front weights by formula then establishing a working ratio is clearly important but the distance method achieves that goal.  Since you are using an average from a sampling which smoothes out errors either in measurement or execution, I presume that a few percentage points difference is not critical to the outcome—there will be built in errors along the way anyway.  <o:p></o:p><o:p> </o:p>As a practical matter, at least for me, I have found that measuring the action ratio by distance, either by product of levers or direct measurement, is more reliable than taking sample weights and then determining the SWR.  Once the action ratio is determined, and sampling is useful as executions on actions can be faulty, then the front weight target and strike weight targets can be determined using a bit of algebra and your equation of balance (thank you for that).  At that point I believe (correct me if I’m wrong) your method is to use that as a guide to preset a smooth front weight curve.  Others, like me, prefer to use those calculations as a guide to ensure that the front weights fall in a specific range (not to heavy or too light) and then set each note individually by uniform balance weight.  Because of inevitable small variations in the note to note executions through the action (balance rail, capstan, knuckle, etc) I find that if a smooth front weight is attempted that the balance weight will need to float (assuming you have a smooth strike weight curve), something I believe you mentioned in a post some time ago that you allow.  I prefer that the front weight float a bit as the inertia differences owing to small differences in front weights are small in the whole scheme of things compared to the floating upweight or downweight curve that will happen if you try and smooth the front weights. Sadly, in practice there is enough error in the executions that you can’t have it both ways, at least that’s what I find. <o:p></o:p><o:p> </o:p>As far as the relationship between your SWR and the distance ratio and that DR/WR > 1, I can’t really comment as to why that would be or what that means exactly.  I take you at your word that you have found examples of that relationship as you are determining it and that they have seemed meaningful in terms of action performance.  But since I don’t know your method of measuring distance ratio or the exact way in which you determine SWR re UW and DW measurements or what and how you are assessing “the best action setups” it’s hard for me to comment.   I’m interested though! <o:p></o:p><o:p> </o:p><o:p> </o:p><table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 width=876 style='width:657.0pt;margin-left:-.75pt;border-collapse:collapse'><tr style='height:10.5pt'><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'>U<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'>D<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'>SW<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'>FW<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'>KR<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'>BW<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'>F<o:p></o:p></td><td width=31 nowrap valign=bottom style='width:23.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'></td><td width=73 nowrap valign=bottom style='width:55.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'>SWR<o:p></o:p></td><td width=61 nowrap valign=bottom style='width:46.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'></td><td width=85 nowrap valign=bottom style='width:64.0pt;padding:0in 5.4pt 0in 5.4pt;height:10.5pt'></td></tr><tr style='height:13.5pt'><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=31 nowrap valign=bottom style='width:23.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=73 nowrap valign=bottom style='width:55.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=61 nowrap valign=bottom style='width:46.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=85 nowrap valign=bottom style='width:64.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td></tr><tr style='height:13.5pt'><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>61 <o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>81<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>12.4 <o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>10.0 <o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>0.50 <o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>71<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>10.0 <o:p></o:p></td><td width=31 nowrap valign=bottom style='width:23.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=73 nowrap valign=bottom style='width:55.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>5.81<o:p></o:p></td><td width=61 nowrap valign=bottom style='width:46.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=85 nowrap valign=bottom style='width:64.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td></tr><tr style='height:13.5pt'><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>71 <o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>96<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>14.6 <o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>10.0 <o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>0.50 <o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>83.5<o:p></o:p></td><td width=89 nowrap valign=bottom style='width:67.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>12.5 <o:p></o:p></td><td width=31 nowrap valign=bottom style='width:23.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=73 nowrap valign=bottom style='width:55.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'>5.79<o:p></o:p></td><td width=61 nowrap valign=bottom style='width:46.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td><td width=85 nowrap valign=bottom style='width:64.0pt;padding:0in 5.4pt 0in 5.4pt;height:13.5pt'></td></tr></table><o:p> </o:p><o:p> </o:p><table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 width=541 style='width:406.0pt;margin-left:-.75pt;border-collapse:collapse'><tr style='height:12.0pt'><td width=72 nowrap valign=bottom style='width:.75in;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td><td width=72 nowrap valign=bottom style='width:.75in;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>Ea<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>Ra<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td><td width=72 nowrap valign=bottom style='width:.75in;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>Ratio<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td><td width=109 nowrap valign=bottom style='width:82.0pt;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td></tr><tr style='height:12.0pt'><td width=72 nowrap valign=bottom style='width:.75in;border:none;border-right:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>Key<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;background:#92D050;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>260<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;background:#92D050;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>128<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td><td width=72 nowrap valign=bottom style='width:.75in;border:solid windowtext 1.0pt;border-top:none;background:yellow;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>0.49<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td><td width=109 nowrap valign=bottom style='width:82.0pt;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td></tr><tr style='height:12.0pt'><td width=72 nowrap valign=bottom style='width:.75in;border:none;border-right:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>Wippen<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;background:#92D050;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>63<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;background:#92D050;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>99<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td><td width=72 nowrap valign=bottom style='width:.75in;border:solid windowtext 1.0pt;border-top:none;background:yellow;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>1.57<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td><td width=109 nowrap valign=bottom style='width:82.0pt;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>Action Ratio<o:p></o:p></td></tr><tr style='height:12.0pt'><td width=72 nowrap valign=bottom style='width:.75in;border:none;border-right:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>Shank<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;background:#92D050;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>17<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;background:#92D050;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>127<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td><td width=72 nowrap valign=bottom style='width:.75in;border:solid windowtext 1.0pt;border-top:none;background:yellow;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>7.47<o:p></o:p></td><td width=72 nowrap valign=bottom style='width:.75in;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'></td><td width=109 nowrap valign=bottom style='width:82.0pt;border:solid windowtext 1.0pt;background:yellow;padding:0in 5.4pt 0in 5.4pt;height:12.0pt'>5.78<o:p></o:p></td></tr></table><o:p> </o:p><o:p> </o:p><o:p> </o:p><o:p> </o:p>David Love<o:p></o:p>www.davidlovepianos.com<o:p></o:p><o:p> </o:p><o:p> </o:p>-----Original Message----- From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf Of David Stanwood Sent: Sunday, September 23, 2012 3:55 AM To: pianotech@ptg.org Subject: Re: [pianotech] Action Ratio measuring<o:p></o:p><o:p> </o:p>>Date: Fri, 21 Sep 2012 07:56:11 -0700<o:p></o:p>>From: "David Love" <<a href="mailto:davidlovepianos@comcast.net">davidlovepianos@comcast.net</a>><o:p></o:p><o:p> </o:p>>BTW just one added comment.  Calculating the action ratio by weight, as <o:p></o:p>>in the Stanwood SWR method, I have found to be totally unreliable as <o:p></o:p>>there are simply too many opportunities for measurement error.<o:p></o:p><o:p> </o:p>>David Love<o:p></o:p><o:p> </o:p>Dear David Love et al,<o:p></o:p><o:p> </o:p>I've been trying to understand your statement: "Calculating the <o:p></o:p>action ratio by weight".   Do you mean calculating the distance ratio <o:p></o:p>by the weight method?  If so I think it is important to distinguish between distance and weight ratios.  One is influenced by gravity vectors and the other not.  So they are not necessarily the same.  I stand by my opinion published in the PTG Journal that the best action setups exhibit a distance ratio that is equal to or higher than the weight ratio, the higher the better.  This relationship is effected by the set up of the arc geometry, an important and deep subject indeed.<o:p></o:p><o:p> </o:p>I defend the calculation of SWR or Strike Weight Ratio as a viable and reasonably repeatable method.  Those of us who practice Component Touch Weight balancing know that the determination of the SWR or Strike Weight Ratio level is an essential ingredient for calculating Front Weight Specifications.  The technique has been practiced and continues to be a highly valued tool by many in our profession. <o:p></o:p>Those of us who utilize this method know that calculating Strike Weight Ratio on a single note and drawing a conclusion about the action as a whole is, in your words: "totally unreliable".  However, as soon as a greater number of measures are taken and averages looked at, the information becomes more and more reliable and totally useful.<o:p></o:p><o:p> </o:p>I suggest the same statistical approach when drawing conclusions about the calculation or measurement of distance ratios.  Best to measure sample notes across the keyboard and look at the average level of the action as a whole.  There are plenty of opportunities for error in measuring between distance points as we see by the <o:p></o:p>discussion and questions.   Also there are naturally variations in <o:p></o:p>action ratio due simply to unevenness in the construction of action components.  Balance Rail pin lines are not straight, capstan lines vary a lot, and when you look closely at knuckle placement you will <o:p></o:p>find there is plenty of opportunity for variation.   Add this to <o:p></o:p>measuring errors and we have a good formula for cumulative error or variation which result in action ratios that uneven by varying degrees from note to note.  Statistical method is the only way to avoid or minimize false perception and this means taking enough samples to draw real conclusions.<o:p></o:p><o:p> </o:p>In my work and consulting we use three levels of sampling:<o:p></o:p><o:p> </o:p>Minimal = middle c2,c#2c4,c#4,c6,c#6 or notes 16,17,40,41,64,65  for quick evaluation<o:p></o:p>Partial = all the c, c#s    for determination of levels<o:p></o:p>Full    = all 88 notes      For StrikeWt calibration and <o:p></o:p>documentation of the action "as was"<o:p></o:p><o:p> </o:p>Hope this helps.<o:p></o:p><o:p> </o:p>David Stanwood<o:p></o:p><o:p> </o:p></div></body></html>