---------------------- multipart/mixed attachment >Ron, > >The moment of inertia has nothing to do with stiffness. It has to do with >where the mass is. The inertia of the shank is a tiny fraction of the >total inertia of the shank and hammer system. The hammer head is where the >big moment of inertia is. The stiffness of the shank is important so that >the hammer head does not wiggle and wobble. At the same time, a heavy >shank would put mass where we don't want it, but even in the shank, it >depends upon where the mass is. Jim. This is the moment of inertia calculation that is a part of all of the various flexure formulae used to calculate beam deflection under static load. In inches and pounds: Deflection of center loaded beam=(weight*length^3)/(48*E*I) where E is the modulus of elasticity, and I the moment of inertia determined by the shape and cross sectional dimensions. >If we are interested in stiffness, I think the best thing to do is to >measure it. That's what I plan to do, when I get time. There are just too >many variables in a stick of wood to try to calculate it. > >Jim Ellis If all that's desired is a relative stiffness of different cross sectional profiles made from the same material, the variation in wood is the best justification I know for calculation, because calculation removes that variation. I was just trying to supply a quick shorthand indicator of that relative stiffness. Ron N ---------------------- multipart/mixed attachment --- Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.538 / Virus Database: 333 - Release Date: 11/10/2003 ---------------------- multipart/mixed attachment--
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