At Mr. Stanwood's Malibu PTD training a couple weeks ago, he gave us a quick and foolproof way to assess ratio by weight in the field. I'll divulge the exact protocol tomorrow when I see my notes. Even better: Maestro? Are you lurking? Can you give the exact protocol, please? When you have "snapshots" of both weight and distance numbers, you can then calculate the action's efficiency ratio---please see Stanwood's previous post in this thread...we're getting more and more intentional, custom, and precise, all in the name of artist inspiration. Hallelujah. David A. On Mar 17, 2009, at 7:26 PM, erwinspiano at aol.com wrote: > -Hi Bob & Frank/All > I appreciate your words of support Frank and the confirmation of > your research & may I just say that Bob & I did have this discussion > & the merit of his suggested method uses more of the complete motion > to assess overall action ratio. > Dave Stanwoods comments about the action ratio gauge being a tool > to get you close but should not consider it a scientific tool is > also notworthy & for microspoic analysis I suggest more complete > study before pinning down a final conclusion > However for quick work in the field or on the bench the action > ratio gauge set up with the 6 mm foot will give a close infield > ballpark reading. For example if the gauge reads a hammer rise of 36 > mm, this is a 6 to 1 ratio. Note thought It is 9 or 10 mm short of > using a complete hammer blow distance of 45 mm which I see in many > Stwy pianos & others > I thought about doing some experiments by modifying the foot on > my gauge to 8 mm. A 6 to 1 ratio with An 8 mm foot will cause 48 mm > of hammer rise. In which case the let-off button would need to be > screwed up on many actions which is only slightly inconvenient but > This modification would take into account more of the hammer travel > as Bob suggested. > Of course a lower ratio say 5.5 to 1 creates only 44 mm of hammer > rise so in most c ases would be very workable. Routinely though > action ratios seem to average something like 5.3 to 6.3.Yes, there > are anomaly on either side of this. > I think I'll do some comparison testing of a 6 mm & 8 mm foot on > the action ratio block & see how much of a difference is had by > allowing more of the entire key stroke come into the equation. This > may be especially important when diagnosing the angled capstan > systems we've been discussing. > I will say even using it with the 6 mm foot has given me a > Polaroid snapshot & better quick idea to begin assessing the > direction of the entire job than using nothing at all, which is what > I do when I have no tools handy. How bout you'all? > Dale > > In a message dated 3/15/2009 3:09:38 P.M. Pacific Daylight Time, pianoguru at cox.net > writes: > Dale Erwin’null practice of measuring hammer movement for a > predetermined key movement is much superior for determining the > ratios. > When this came up a couple of months ago,20I pointed out that the > weakness in this (which in Dale'null method used only a fixed, > limited portion of keystroke) lies in the (unpredictably) changing > ratios as the action goes through its motions. I prefer to use the > whole keystroke, using a fixed setup of 1.75 inches blow (only for > measurement - I might change it later); .040 null (ditto), and an > otherwise regulated note, to see what kind of dip it produces. I > think this gives me a more accurate feel for the whole distance > ratio, and has the advantage of using larger movements which I think > increase the accuracy. > > Bob Davis > > Need a job? Find employment help in your area. > > Live traffic, local info, maps, directions and more with the NEW > MapQuest Toolbar. Get it now! -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090317/c72e132c/attachment.html>
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