<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=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>The problem, as far as the formula is concerned, is that the .040, .050, .060 do not comport with the formula requirements (I assume the equality was based on something).  And your point is suggestive of the fact that the bit of key travel is not really the critical factor.  Rather, it is jack clearance from some yet unknown starting point.  So aftertouch for the sake of that formula may be something other than what we think of as it relates to the thickness of the cardboard placed underneath the key.  That’s the main point of the question.<o:p></o:p><o:p> </o:p>Regarding ideal specs and action ratios (let’s put aside for the moment that the method of determining the ratio is something of a debate), there is no getting around the fact that a certain action ratio will tend to produce a particular regulation or combination of dip and blow, all other things being equal, i.e. let-off, aftertouch, jack position, knuckle diameter, capstan angle perhaps…).  If your ideal is 45 mm with .390” dip  (or 9.9 mm to keep the units the same), then you will only get that regulation with a particularly action ratio.  You won’t get that with 5.0 and you won’t get that with 6.5 unless you alter the let-off or the aftertouch and at both extremes that is likely going to be detrimental.  <o:p></o:p><o:p> </o:p>Now I think that 9.9 mm dip, or let’s just say 10 mm for ease here, and 45 mm of blow is a good target.  So my question is, in your experience, what action ratio is most likely to produce that without any fudging and further, what standard of cardboard punching thickness key travel are you using, ideally anyway.<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><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf Of Dale Erwin Sent: Sunday, August 26, 2012 7:32 PM To: pianotech@ptg.org Subject: Re: [pianotech] action ratio<o:p></o:p></div><o:p> </o:p>Last Sat. Laroy Edwards and I taught a joint class in my shop to members of several local chapters in the region. Great fun and the Head piano Meister at 84 yrs young; ... was on his game. <o:p></o:p><div>  I had the pleasure of sitting in his "after touch class". where He clearly defined after touch. <o:p></o:p></div><div><o:p> </o:p></div><div>  Short story is that after touch begins as soon as the jack escapes the knuckle. How far it moves past that is the real after touch number/distance/feel. One limiting factor to jack movement and hence after touch is determined by the total length of the repetition lever slot. The jack cannot move beyond the rep.lever slot stop with out the jack tender binding and then breaking off. Bummer. Ca glue please anybody.<o:p></o:p></div><div><o:p> </o:p></div><div>  Another limiting factor is that the jack must escape enough that it DOES NOT have opportunity to dance with the knuckle and do the mister booble head thing. With repetition in mind the farther the jack escapes the farther it has to travel back, and we all know this of course will slow repetition.<o:p></o:p></div><div> <o:p></o:p></div><div>   So within those  parameters in mind some variability is allowed/acceptable based on subjective feel. I'll leave it at that for now. Using Davids cardboard method to just sense jack escapement is quite good I think.  Many techs that use this method state a preference like..... "I like .040....050 ...060. cardboard placed on top of the front punching as there sensory gauge" <o:p></o:p></div><div> So these are small parameters to be sure but we and our pianists clients live in the realm of the subjective. Some like dip/key travel deep some like it so short that mister bobble head can almost dance and these folks, oddly enough....have learned to control it.<o:p></o:p></div><div> <o:p></o:p></div><div> Dip.<o:p></o:p></div><div>  This Sticky wicket wording to me always needs clarification<o:p></o:p></div><div>   So this means to me overall key travel top to bottom. How we measure it will be confusing unless we speak specifically how we do that. In setting up any action regulation parameters I am  looking for roughly those numbers David suggests. ie. 45mm or 1 3/4 blow....Let off at approx. .050/1.3mm,  <o:p></o:p></div><div>(I like it close.) and a .390 dip.  I measure that just in front of the key pin & right under where the finger touches the key much of the time with a direct measurement gauge. (the Erwin dip gauge)<o:p></o:p></div><div> ( see picture.)  Now I realize that the key travel depth can vary given the wide variance of action ratios, typically 5 to 6.5, but actions that fall within what we all refer to as normal compliance, fall into these numbers routinely. So its at least a starting point when looking for parameters.<o:p></o:p></div><div>Other folks measure at the very front of the key with a metric ruler. Whatever works<o:p></o:p></div><div><o:p> </o:p></div><div> Another consideration is that the standard green front rail punching available can easily squish .035. <o:p></o:p></div><div>That seems like a lot don't ya think? This is not a promotional but the fairly new Cresendo punching compress a very predictable .015. So,.... over all key travel can be set very precisely. Some don't like the feel but that's another story. So overall dip/key travel set from a basically static method changes quite variably under different dynamic ranges/key pressures with the green squishy punching. <o:p></o:p></div><div> So now;... what is the dip really?<o:p></o:p></div><div>  I just wanted to clarify some other reasons why Jim might be a bit confused since I was thinking about it lately.<o:p></o:p></div><div>  <o:p></o:p></div><div><o:p> </o:p><div>Dale Erwin R.P.T. Erwin's Piano Restoration Inc. Mason & Hamlin/Steinway/U.S. pianos <a href="http://www.Erwinspiano.com">www.Erwinspiano.com</a> Phone: 209-577-8397 <tt> </tt> <tt>  </tt><o:p></o:p></div><o:p> </o:p><div>-----Original Message----- From: David Love <<a href="mailto:davidlovepianos@comcast.net">davidlovepianos@comcast.net</a>> To: pianotech <<a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a>> Sent: Sun, Aug 26, 2012 11:51 am Subject: Re: [pianotech] action ratio<o:p></o:p><div id="AOLMsgPart_0_cea1fe86-c92b-4ac4-ae2e-1a399da24379"><pre style='background:white'><tt>I don't quite think it's apples to oranges because for any given action<o:p></o:p></tt></pre><pre style='background:white'><tt>ratio there will be at least a limitation to the regulation specs or the<o:p></o:p></tt></pre><pre style='background:white'><tt>dip/blow relationship.  I agree that the formula is confusing but I don't<o:p></o:p></tt></pre><pre style='background:white'><tt>think it has to be.  Determining when let-off and aftertouch actually start<o:p></o:p></tt></pre><pre style='background:white'><tt>seems to be the problem.  Once established, however, I see no reason why a<o:p></o:p></tt></pre><pre style='background:white'><tt>default setting for the sake of this formula can't be used.  Moreover, I<o:p></o:p></tt></pre><pre style='background:white'><tt>find that it's the aftertouch part that is confusing.  As far as the formula<o:p></o:p></tt></pre><pre style='background:white'><tt>goes, my own experience suggests that a let-off number of 1.5 and an<o:p></o:p></tt></pre><pre style='background:white'><tt>aftertouch number of 2.5 produces regulation specs that I expect to find<o:p></o:p></tt></pre><pre style='background:white'><tt>with a given action ratio.  The problem seems to be defining exactly what<o:p></o:p></tt></pre><pre style='background:white'><tt>aftertouch is, at least as it pertains to this formula.  Blow, dip and<o:p></o:p></tt></pre><pre style='background:white'><tt>let-off are more easily defined.   <o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>David Love<o:p></o:p></tt></pre><pre style='background:white'><tt><a href="http://www.davidlovepianos.com" target="_blank">www.davidlovepianos.com</a><o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>-----Original Message-----<o:p></o:p></tt></pre><pre style='background:white'><tt>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<o:p></o:p></tt></pre><pre style='background:white'><tt>Of Jim Ialeggio<o:p></o:p></tt></pre><pre style='background:white'><tt>Sent: Sunday, August 26, 2012 8:32 AM<o:p></o:p></tt></pre><pre style='background:white'><tt>To: <a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a><o:p></o:p></tt></pre><pre style='background:white'><tt>Subject: [pianotech] action ratio<o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>David L said:<o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt><The question at hand has to do with what exactly is the after touch spec<o:p></o:p></tt></pre><pre style='background:white'><tt>that's used to make the formula ratio by product of the levers equal to the<o:p></o:p></tt></pre><pre style='background:white'><tt>blow/dip ratio as given.<o:p></o:p></tt></pre><pre style='background:white'><tt>(and)<o:p></o:p></tt></pre><pre style='background:white'><tt><But when I input those numbers in this calculator, as you can see, then by<o:p></o:p></tt></pre><pre style='background:white'><tt>that formula a 5.75 AR with 45 mm of blow distance should regulate with 8.6<o:p></o:p></tt></pre><pre style='background:white'><tt>mm of dip.<o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>This illustrates the confusion I find in these formulas, if they are to be<o:p></o:p></tt></pre><pre style='background:white'><tt>used from a design perspective rather than as a ballpark reactive position<o:p></o:p></tt></pre><pre style='background:white'><tt>in the field. I feel the (blow distance-let off)/key<o:p></o:p></tt></pre><pre style='background:white'><tt>dip-aftertouch) part of the equation, when compared to the lever arms part<o:p></o:p></tt></pre><pre style='background:white'><tt>of the equation is apples to oranges.<o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>The lever arm side of the equation looks at the lever arms as the product of<o:p></o:p></tt></pre><pre style='background:white'><tt>fixed ratios.  However, the blow distance ratio does not look at blow<o:p></o:p></tt></pre><pre style='background:white'><tt>distance and key dip as fixed ratios, but rather inputs arbitrary<o:p></o:p></tt></pre><pre style='background:white'><tt>letoff/aftertouch as necessary to make that side of the equation match the<o:p></o:p></tt></pre><pre style='background:white'><tt>fixed ratio side, as I think you've noted, David.  Or seen another way, if<o:p></o:p></tt></pre><pre style='background:white'><tt>you are going to use the blow distance side of the equation as given, then<o:p></o:p></tt></pre><pre style='background:white'><tt>the lever arm side must take into consideration the whip's changing leverage<o:p></o:p></tt></pre><pre style='background:white'><tt>and the shank's changing leverage during letoff. This changing leverage<o:p></o:p></tt></pre><pre style='background:white'><tt>presents difficulties that would require computing complexities way beyond<o:p></o:p></tt></pre><pre style='background:white'><tt>simple algebra.<o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>Taken in this light, your shy 8.6mm dip could be more a result of blow being<o:p></o:p></tt></pre><pre style='background:white'><tt>quantified artificially.  According to the fixed leverages, blow is not the<o:p></o:p></tt></pre><pre style='background:white'><tt>distance between hammer at rest and the strings minus letoff, but rather<o:p></o:p></tt></pre><pre style='background:white'><tt>(Full unimpeded travel of the hammer with out any letoff or<o:p></o:p></tt></pre><pre style='background:white'><tt>strings) = Action ratio*(key dip-aftertouch).<o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>By the way, my comment here is not that this formula doesn't empirically<o:p></o:p></tt></pre><pre style='background:white'><tt>work, but rather that the thinking behind it seems to be selective and thus<o:p></o:p></tt></pre><pre style='background:white'><tt>confusing, at least to me.<o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>Jim Ialeggio<o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>-- <o:p></o:p></tt></pre><pre style='background:white'><tt>Jim Ialeggio   <o:p></o:p></tt></pre><pre style='background:white'><tt><a href="mailto:jim@grandpianosolutions.com">jim@grandpianosolutions.com</a><o:p></o:p></tt></pre><pre style='background:white'><tt>978 425-9026<o:p></o:p></tt></pre><pre style='background:white'><tt>Shirley Center, MA<o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre></div></div></div></div></body></html>