<font color='navy' size='2' face='Comic Sans MS, sans-serif'><font color="#000080" face="Comic Sans MS, sans-serif" size="2">Isn't that about a 3 to 1 ratio.3mm=approx.125. </font> <div><font color="#000080" face="Comic Sans MS, sans-serif" size="2">.040 </font><font color="#000080" face="Comic Sans MS, sans-serif">divided</font><font color="#000080" face="Comic Sans MS, sans-serif" size="2"> into .120 is 3. Does this mean anything?</font><br> <br> <div style="color: navy; font-family: 'Comic Sans MS', sans-serif; font-size: 10pt; clear: both; "><font size="1" color="royalblue"><b><font face="Georgia, Times New Roman, Times, Serif"><font color="black"><font color="mediumblue" face="Comic Sans MS, sans-serif">Dale Erwin R.P.T.<br> <font color="green">Erwin's Piano Restoration Inc.</font><br> </font></font></font></b></font><font color="darkgreen"><span style="font-style: italic;"><b><font size="1"><font size="1" color="black"><font color="blueviolet"><font color="black"> <font color="black" face="Comic Sans MS, sans-serif">Mason & Hamlin</font><font face="Comic Sans MS, sans-serif">/Steinway/</font><font color="black" face="Comic Sans MS, sans-serif">U.S. pianos</font><font face="Comic Sans MS, sans-serif"><br> </font></font></font></font><font size="1" color="cornflowerblue" face="Comic Sans MS, sans-serif">www.Erwinspiano.com</font><font size="1"><br> </font><font size="1" color="crimson" face="Comic Sans MS, sans-serif">Phone: 209-577-8397</font><br> <font color="darkgreen"></font></font></b></span></font><tt><tt><font color="darkgreen"><br>  </font><br>   <font size="2"></font></tt></tt><br> <br> </div> <br> <br> <div style="color: black; font-family: arial, helvetica; font-size: 10pt; ">-----Original Message-----<br> From: David Love <davidlovepianos@comcast.net><br> To: pianotech <pianotech@ptg.org><br> Sent: Wed, Aug 29, 2012 6:48 am<br> Subject: Re: [pianotech] action ratio<br> <br> <div id="AOLMsgPart_2_b547f62a-75aa-4edf-9c20-524842444866"> <div class="WordSection1"> <div class="MsoNormal"><span style="color:#1F497D">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.  </span></div> <div class="MsoNormal"><span style="color:#1F497D"> </span></div> <div class="MsoNormal"><span style="color:#1F497D"> </span></div> <div> <div class="MsoNormal"><span style="color:#1F497D">David Love</span></div> <div class="MsoNormal"><span style="color:#1F497D"><a href="http://www.davidlovepianos.com" target="_blank">www.davidlovepianos.com</a></span></div> </div> <div class="MsoNormal"><span style="color:#1F497D"> </span></div> <div> <div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in"> <div class="MsoNormal"><b><span style="font-size:10.0pt;font-family:">From:</span></b><span style="font-size:10.0pt;font-family:"> David Love [<a href="mailto:davidlovepianos@comcast.net?">mailto:davidlovepianos@comcast.net</a>] <br> <b>Sent:</b> Monday, August 27, 2012 7:35 AM<br> <b>To:</b> '<a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a>'<br> <b>Subject:</b> Re: [pianotech] action ratio</span></div> </div> </div> <div class="MsoNormal"> </div> <div class="MsoNormal"><span style="color:#1F497D"> </span></div> <div> <div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in"> <div class="MsoNormal"><b><span style="font-size:10.0pt;font-family:">From:</span></b><span style="font-size:10.0pt;font-family:"> <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>] <b>On Behalf Of </b>David Love<br> <b>Sent:</b> Monday, August 27, 2012 7:27 AM<br> <b>To:</b> <a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a><br> <b>Subject:</b> Re: [pianotech] action ratio</span></div> </div> </div> <div class="MsoNormal"> </div> <div class="MsoPlainText">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<span style="color:#1F497D"> </span>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). </div> <div class="MsoPlainText"> </div> <div class="MsoPlainText">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.</div> <div class="MsoPlainText"> </div> <div class="MsoPlainText"><a target="_blank" 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.</div> <div class="MsoPlainText"> </div> <div class="MsoPlainText">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.  </div> <div class="MsoPlainText"> </div> <div class="MsoPlainText">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.  </div> <div class="MsoPlainText"> </div> <div class="MsoPlainText">David Love</div> <div class="MsoPlainText"><a target="_blank" href="http://www.davidlovepianos.com">www.davidlovepianos.com</a></div> <div class="MsoPlainText"> </div> <div class="MsoPlainText"> </div> <div class="MsoPlainText">-----Original Message-----<br> 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<br> Sent: Monday, August 27, 2012 5:59 AM<br> To: <a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a><br> Subject: Re: [pianotech] action ratio</div> <div class="MsoPlainText"> </div> <div class="MsoPlainText">On 8/27/2012 6:54 AM, Jim Ialeggio wrote:</div> <div class="MsoPlainText">> Right...The regulation and especially fine regulation by feel are </div> <div class="MsoPlainText">> points well taken, and are how I proceed in the real world.</div> <div class="MsoPlainText">> </div> <div class="MsoPlainText">> My simple brain looked at the initial post, and interpreted it as a</div> <div class="MsoPlainText">> question: "Are the 2 sides of this equation, mathematically speaking, </div> <div class="MsoPlainText">> not regulation-ally speaking equivalent?"</div> <div class="MsoPlainText">> </div> <div class="MsoPlainText">> My take is no. I think that the formula states terms that are not </div> <div class="MsoPlainText">> equivalent.</div> <div class="MsoPlainText">> </div> <div class="MsoPlainText">> Does it matter...maybe not, especially if the hammers weight is kept </div> <div class="MsoPlainText">> under control. Its only when the shank is swinging a sledge hammer </div> <div class="MsoPlainText">> weight that the functionality bandwidth is driven into OCD land anyway.</div> <div class="MsoPlainText"> </div> <div class="MsoPlainText">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? </div> <div class="MsoPlainText">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.</div> <div class="MsoPlainText"> </div> <div class="MsoPlainText">Ron N</div> <div class="MsoPlainText"> </div> </div> </div>  </div> </div> </font>