But wait. Is that 1:1 metric? ES ----- Original Message ----- From: "Farrell" <mfarrel2 at tampabay.rr.com> To: "Pianotech List" <pianotech at ptg.org> Sent: Monday, May 12, 2008 5:24 AM Subject: Re: Ratio question > Thanks Jon, you saved me the trouble.... > > Terry Farrell > > ----- Original Message ----- >> If you don't measure the dip at the front of the key (where it is 1:1) >> you have to consider the length of the key and the angle formed from >> pivoting on the balance rail and how far back from the front you measure. >> >> For instance, my dip block measures 48 mm in length, >> 9.9 mm (.390") at the front tapering to 8.4 mm. >> >> That's roughly .19 mm decrease for each 6 mm moved back. >> >> But it is much too complicated for the task involved. Not only do you >> have to consider the angle of the key at dip, you have to consider >> the rate of height change on the risen key since it is pivoted at the >> back rail. >> So the height measured 6 mm back on that key will be ever so >> minutely less than the +1mm due to the longer radius (probably half >> the rate of change as the 'dipped' key due to twice the radius). >> >> Keep life simple, measure dip at the front, 1:1. >> >> The amount of dip is dependant on what is required for regulation >> but that's a different topic. >> >> Jon Page >> > > >
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