<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: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=iso-2022-jp"><meta name=Generator content="Microsoft Word 12 (filtered medium)"><style></style></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1>Not to beat a dead horse but FWIW one thing I do notice, with my action model anyway, is that the jack movement (and key movement for that matter) from the point of jack tender contact with the let-off button is about 2.5 – 3 mm which, on my model, translates to about .040” key travel after the point of escapement.  So if “aftertouch”, at least in this formula, is based on travel after contact with the let-off button when the jack starts to move horizontally rather than vertically, then the output of my design chart seems consistent with real world results.  <o:p></o:p><o:p> </o:p><o:p> </o:p><div>David Love<o:p></o:p>www.davidlovepianos.com<o:p></o:p></div><o:p> </o:p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>From: David Love [mailto:davidlovepianos@comcast.net] Sent: Monday, August 27, 2012 7:35 AM To: 'pianotech@ptg.org' Subject: Re: [pianotech] action ratio<o:p></o:p></div></div><o:p> </o:p><o:p> </o:p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>From: <a href="mailto:pianotech-bounces@ptg.org">pianotech-bounces@ptg.org</a> [<a href="mailto:pianotech-bounces@ptg.org">mailto:pianotech-bounces@ptg.org</a>] On Behalf Of David Love Sent: Monday, August 27, 2012 7:27 AM To: <a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a> Subject: Re: [pianotech] action ratio<o:p></o:p></div></div><o:p> </o:p>I think the formula states an equality which is mathematically consistent.  Attached is an updated version of the calculator and you can write it in terms of the dependent variable being any one of the outputs.  I've done it in terms of Dip and Aftertouch.  Change any one of the inputs and you will get an output which is consistent with what must happen in the action.  The question is simply what value should be assigned to aftertouch that comports with a real world action (that may well be different from how we actually regulate aftertouch in the field). <o:p></o:p><o:p> </o:p>Re Ron's comments, Inertia is not Mass x Acceleration.  That would be force.  Inertia is a function of force, mass and the distance from the axis of rotation, in this case, and gets expressed in simple terms as I = ∑ mr^2.  It uses force as a component but it’s not the same thing as force.<o:p></o:p><o:p> </o:p><a href="http://easycalculation.com/physics/classical-physics/moment.php">http://easycalculation.com/physics/classical-physics/moment.php</a> offers a convenient calculator for sake of illustration.<o:p></o:p><o:p> </o:p>I agree with Ron that the issue is not that a key has seven leads.  The issue is that the relationship between the action ratio and the hammer weight (or strike weight if you prefer) creates a system of high or low inertia that also requires seven leads to balance at some designated target.  Regardless of the attempt at balancing, the addition of lead doesn’t change the fundamentally high inertia in the system that results, in this case, from a combination of high action ratios and high hammer weights.  (BTW the relationship can also be too low—low action ratios and low hammer weights are also a problem).  That relationship has an acceptable target range and (back to this discussion) the regulation requirements necessarily associated with a particular action ratio narrow the range even further unless we are willing to wander from our conventional (and sometimes changing) dip/blow standards.  <o:p></o:p><o:p> </o:p>The issue of inertia is something that Darrell Fandrich and John Rhodes have tried to address and discussed at the recent national convention in the class “Actions To Die For” and refer to as the Inertial Touch Force, or ITF.  <o:p></o:p><o:p> </o:p>David Love<o:p></o:p><a href="http://www.davidlovepianos.com">www.davidlovepianos.com</a><o:p></o:p><o:p> </o:p><o:p> </o:p>-----Original Message----- From: <a href="mailto:pianotech-bounces@ptg.org">pianotech-bounces@ptg.org</a> [<a href="mailto:pianotech-bounces@ptg.org">mailto:pianotech-bounces@ptg.org</a>] On Behalf Of Ron Nossaman Sent: Monday, August 27, 2012 5:59 AM To: <a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a> Subject: Re: [pianotech] action ratio<o:p></o:p><o:p> </o:p>On 8/27/2012 6:54 AM, Jim Ialeggio wrote:<o:p></o:p>> Right...The regulation and especially fine regulation by feel are <o:p></o:p>> points well taken, and are how I proceed in the real world.<o:p></o:p>><o:p> </o:p>> My simple brain looked at the initial post, and interpreted it as a<o:p></o:p>> question: "Are the 2 sides of this equation, mathematically speaking, <o:p></o:p>> not regulation-ally speaking equivalent?"<o:p></o:p>><o:p> </o:p>> My take is no. I think that the formula states terms that are not <o:p></o:p>> equivalent.<o:p></o:p>><o:p> </o:p>> Does it matter...maybe not, especially if the hammers weight is kept <o:p></o:p>> under control. Its only when the shank is swinging a sledge hammer <o:p></o:p>> weight that the functionality bandwidth is driven into OCD land anyway.<o:p></o:p><o:p> </o:p>And this is hardly an isolated incidence. A few years ago when the big get lead out of the keys at any cost to lower inertia crusade passed through the CAUT world I tried to point out that the keys wouldn't have seven leads in them if the action ratio and hammer weight didn't demand it for static balance. Inertia is mass times acceleration, but which mass? Inertia down is a hammer problem, not a key weight problem because the hammer is accelerating at over five times the key's rate. The key is not in free fall, so whether it's being depressed faster than free fall under earth's gravity is irrelevant as the hammer on the under end of the lever train is being lifted against gravity at the same time. As key acceleration increases, hammer acceleration also increases at over five times that rate. Key inertia becomes a problem on release, when the rep spring has to lift the key to reset the jack. So how do we set rep spring strength? By hammer rise, which doesn't happen in actual play. So shouldn't we be setting rep spring strength with key rise instead? <o:p></o:p>Pretty much everything we do in a piano is a workaround, an average, a compromise, or a substitute representing the current method giving us a result similar to what we think we want, when it's done under certain conditions. Sure, we have to start somewhere, but we also have to rethink our premise too, just like measuring action ratio. This is a first rate resource for doing just that to get observations we might not have made ourselves. There are still lots of loose ends but questions are still being defined to try to deal with them. Is good.<o:p></o:p><o:p> </o:p>Ron N<o:p></o:p><o:p> </o:p></div></body></html>