Perhaps David Stanwood could weigh in on this. No doubt he's experienced this in his massive studies of such things. <div style="color: navy; font-family: 'Comic Sans MS', sans-serif; font-size: 10pt; clear: both;">Dale Erwin R.P.T. Erwin's Piano Restoration Inc. <tt><tt>     </tt></tt> </div> <div style="color: black; font-family: arial, helvetica; font-size: 10pt;">-----Original Message----- From: David Love <davidlovepianos@comcast.net> To: pianotech <pianotech@ptg.org> Sent: Wed, Jan 16, 2013 5:17 pm Subject: Re: [pianotech] Measuring Action Ratios <div id="AOLMsgPart_0_ed776801-2a7d-445d-86fe-5a2982489872" style="margin: 0px;font-family: Tahoma, Verdana, Arial, Sans-Serif;font-size: 12px;color: #000;background-color: #fff;"> <pre style="font-size: 9pt;"><tt>Yes I did! Where to measure from and to seems to be a subject of some debate. I'm aware of the other protocols and there are others besides the one you mention. The discrepancy isn't to do with where I'm measuring from. It is very unlikely that this action has a 5.2 ratio as measured by the key travel/hammer movement method. The 5.87 that I got from this lever arm measuring is consistent both with how the action regulates and the weight based formulas (Stanwood) that I use for determining strike weights with targeted balance and front weights , (not to mention how many of the older MH actions were set up). I have tried every method that I know of for measuring action ratios (including the one you mention) and this one I find the most reliable and consistent with the weight formulas as I use them and regulation predictions. In this case the key travel/hammer travel relationship is not consistent with the actual action ratio no matter how you measure it. That is the crux of the matter. David Love <a href="http://www.davidlovepianos.com" target="_blank">www.davidlovepianos.com</a> -----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 Jim Ialeggio Sent: Wednesday, January 16, 2013 4:39 PM To: <a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a> Subject: [pianotech] Measuring Action Ratios David Love wrote: <Shank Ea is measured from the hammer flange center pin to the center of the knuckle core (measured along the shank) . <Shank Ra is measured from the hammer flange center pin to the center of the hammer molding (measured along the shank). Did you mean to write this David??? Shank Effort arm, or in my terminology shank lower lever, is center pin to full projection of knuckle...center pin to full projection of the knuckle is the hypotenuse of a right triangle rather than the adjacent side you called out. LIke-wise, Shank Resistance arm, on in my terminology shank upper lever, is shank center pin to strike point on the hammer. Again, it is a hypotenuse, of a right triangle, rather than the adjacent side you called out along the shank. Perhaps this is what is messing with your numbers??? Jim Ialeggio -- Jim Ialeggio <a href="mailto:jim@grandpianosolutions.com">jim@grandpianosolutions.com</a> 978 425-9026 Shirley Center, MA </tt></pre> </div>  </div>