This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Hi Folks. Been mulling over a lot of whats been written and looking back at Stephen Birkets article and it struck me that we could use these cute new key inertia measuring jigs Mark and John have worked out to do exactly what Birkets article suggests. According to Birkkets paper there a few key expressions based on the following diagram. The breakpoint acceleration is and For the Breakpoint force we have. Now Fst is the exact force we need to exceed in order to get the key moving. This is the same thing as BW * g So.. Fst = BW * g then Mrk = (BW * r) + mrb. which means that the only unknown in any of these expressions is Ik (which we can measure with our MOI jigs) since we can calculate Mrk directly from BW, r, and mrb. So what do we get if we measure and figure these expressions out. Jo !! we get 2 points on the force for accelleration graph.. and using 9th grade geometry we know that (y-y1) = a(x- x1) is the solution for finding a 1st degree equation when two points are known. What we get is Stephens (Fst, a) ( Fbr, a1) In other words....; is the equvilant of Or... since Fst = BW * g and Mrk = (BW * r) + mrb. we have as our two points.. (x,y) (x1,y1) All of which we can easily measure directly without having to rely on knowing the MOI for the (already) leaded key. We only need Ik for a reference (unleaded) key from which, together with a BW specification, we can decide which combinations of m and rb... ie key mass and its radius from the balance rail pin, will yield desireable points on the acelleration for force graph. As long as we can assume that lead evenly distributed about a certain point will to a reasonable degree behave as the point mass used in Birketts equation... we have basically a new equation of balance.... and one that directly accounts for key MOI. Mrk = (BW * r) + mrb Yes ??? Cheers RicB ---------------------- multipart/alternative attachment --------------010907020004070800060601 An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/15/39/30/af/attachment.htm --------------010907020004070800060601 A non-text attachment was scrubbed... Name: moz-screenshot.jpg Type: image/jpeg Size: 8861 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/54/fa/e0/89/moz-screenshot.jpg --------------010907020004070800060601 A non-text attachment was scrubbed... Name: moz-screenshot-1.jpg Type: image/jpeg Size: 1711 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/01/78/fd/77/moz-screenshot-1.jpg --------------010907020004070800060601 A non-text attachment was scrubbed... Name: moz-screenshot-2.jpg Type: image/jpeg Size: 6606 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/b8/46/66/30/moz-screenshot-2.jpg --------------010907020004070800060601 A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 1289 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/be/98/99/93/attachment.jpe --------------010907020004070800060601 A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 2222 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/c1/1c/3c/2b/attachment.jpe --------------010907020004070800060601 A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 2404 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/bf/8c/8b/7c/attachment.jpe --------------010907020004070800060601 A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 4964 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/f9/cc/5b/83/attachment.jpe --------------010907020004070800060601 A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 4943 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/62/b2/bd/f4/attachment.jpe --------------010907020004070800060601-- ---------------------- multipart/alternative attachment--
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