On 2/24/2011 12:33 PM, Encore Pianos wrote: > Thank you for that info. I have had others do these calculations for me > in the past for rib dimensions, and do not have this formula. I would > love to do this calculation myself. Is it possible to ask for this beam > deflection formula? No, absolutely not. It's expressly (that's Elvis Expressly, recently sighted in Fargo) forbidden to divulge this: Deflection formula for center loaded beams, where L=length, H=height, W=width, B=bearing load, and E=modulus of elasticity of the material in PSI. All dimensions in millimeters. Typical E value for Sitka Spruce is about 1,570,000 PSI. With load in pounds: Deflection in mm=(L^3*B)/(E*0.0062*W*H^3) With load in kilos: Deflection in mm=(L^3*B)/(E*0.00281227*W*H^3) If this were to be common knowledge, chaos could result. Hint: It's been posted to pianotech a dozen times or more in years past, and it's on the last page of the handout you got at my all day belly class. It's just the standard flexure formula for center loaded beams. Ron N, not recently sighted
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