I'm having to revisit using distance formulas to correct a serious action problem and in the process have been reminded (thanks Jon) of the Baldassin/Robinson formula of: (keyout/key in) x (wippen out/wippen in) x (shank out/shank in) = (blow distance - letoff)/(key dip-aftertouch) The left side of the equation is common to all of us who use that to calculate the action ratio. But the right side is less common and doesn't really make sense in terms the relationship between action ratios and regulation. While the left side of the equation describes the relationship between key travel and hammer travel unimpeded by let off (for example in an action with a 5.5 ratio, 10 mm of key travel will produce 55 mm of hammer travel). But the right side of the equation doesn't bear much resemblance to that outcome for that type of ratio unless my let off and after touch dimension are quite misguided (I figure 1.5 mm for let off and 1 mm for aftertouch-in reality I use about .030" which is more like .75 mm). I'm curious if anyone has actually used this equality to set up or make a correction on an action. If you use the right side as a guide it will tend to set the target action ratio far too low, in my view. David Love www.davidlovepianos.com -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100105/1838f2ba/attachment.htm>
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