---------------------- multipart/alternative attachment Hi Terry. I think that if we are talking about the leverage ratio of the Piano action... then its effects on weight, distance, and speed for input and output are exactly the same. Take a simple 2:1 ratio lever. 5 grams of input will lift 10 grams. 10 mm movement of input will yeild 5 mm movement output. What speed of movement is found at the input is 2 times that found at the output. Its 2:1 regardless... and hey... thats the law of levers for you. So whatever you use as a method to measure this action ratio of ours... it has to have this consistancy. You have to be able to see that your resulting ratio corresponds with what the lever actually does. You cant just measure a lever in some fashion that doesnt correspond to what it lifts. If your measurements tell you its 2:1 and you find it actually lifts a 2.3 to 1 ratio... then your measurements are either wrong or you are measureing something other then the levers ratio. So this discussion really is more about what constitutes the action ratio. It seems clear to me that the "load" our leverage system is lifting is the hammer itself. Not what could be lifted from the tip of the hammer. So Stanwoods Balance equation has to give the correct result as it is really nothing more then another way (which includes some of the weight parameters) of writing the product of the ratio of the three levers. WR * HSR * KR = R So... to answer your question straight out... of course your method will yeild the correct ratio too... assuming you can measure acurately enough. And you should be able to contrive a pretty decent jig for this. Comparing that to what you get from Stanwoods weight method, and the corresponding direct measurements of the lengths of the arms of the individual levers... and between the three you can come up with a very dependable figure. [Image] Think about it :) Farrell wrote: > Richard. What do you think of the method stated below: > > So is it not best to simply measure how many units of hammer rise you get for each unit of key depression? I have two little blocks that slip under the key front. They have 5 mm difference in height. The taller one will meet the key with just a slight key movement (to avoid any funky stuff right at the immediate start of key/action movement, and the shorter one will meet the key before letoff. Place the taller block under the key front and depress key to meet block. At that point you measure the height of the hammer. Then you place the shorter block under the key and depress the key the additional 5 mm that the shorter block will allow. Again measure hammer height. The blocks allow a very precise 5 mm (or whatever you want to use) keystroke. You should be able to measure hammer height pretty accurately. > > Is the convention to measure key height at the very front tip? > > Seems to me this approach will eliminate any questions about exactly where to measure, etc. Does anyone see any shortcomings with this method? > > Terry Farrell > > > ----- Original Message ----- > From: "Richard Brekne" <Richard.Brekne@grieg.uib.no> > To: <oleg-i@wanadoo.fr>; "Pianotech" <pianotech@ptg.org> > Sent: Sunday, January 19, 2003 7:45 AM > Subject: Re: Action Ratio, was: More off the wall stuff > > > Where does all this mystery come from ? > > > > Davids formula is just another way of applying the law of leverages. Its > > easy enough to factor out the weight components of the equation and > > arrive at a more simple and straightforward equality for the action > > ratio. This is, and can never be anything else then the product of the > > ratios of the three levers. > > > > There has to be consistancy between weight, distance, and speed in a > > levers ratio. Whatever the ratio of any given lever is, its has the same > > effect on these three. This is basic to the law of levers. > > > > Any ratio that results in something else has simply got to be a measure > > of something else. Could be a valuable something else in another > > context, but just so.. > > > > Cheers > > > > RicB > > > > > > Isaac OLEG wrote: > > > > > Terry, > > > > > > The drawback of this method is that the leverage is changing during > > > the stroke (more or less depending of the action setup, kind of > > > whippen, etc... > > > > > > At this moment seems to me that only David's method gives an evened > > > appreciation of what goes on for all the stroke. > > > > > > Regards > > > > > > Isaac OLEG > > > > > > > -- > > Richard Brekne > > RPT, N.P.T.F. > > UiB, Bergen, Norway > > mailto:rbrekne@broadpark.no > > http://home.broadpark.no/~rbrekne/ricmain.html > > > > > > _______________________________________________ > > pianotech list info: https://www.moypiano.com/resources/#archives > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives -- Richard Brekne RPT, N.P.T.F. 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