Think I-beam. Nearly all of the stress is carried by the outer fibers. Drilling through the middle will have negligible effect on the structural integrity. All of the bending load is carried by the top layer and bottom layer. Further, the maximum stress occurs in the middle of the key right at the key pin hole. The biggest cause of key flexure is the slot cut into the key right at the point of max stress. Where you need it the most there is the least section across the top. This is why putting on good key buttons securely yields big improvements. Dean Dean May, BSME, PE cell 812.239.3359 Engineer in my former life (they just never let me blow the whistle) PianoRebuilders.com 812.235.5272 Terre Haute IN 47802 -----Original Message----- From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf Of Farrell Sent: Thursday, December 01, 2005 8:15 AM To: Pianotech Subject: Re: Drilling for key leads and key flex I don't know for sure, as I am not an engineer, but it sure seem likely to me that a hole drilled half-way through the key will induce half the flex that a hole drilled completely through would induce. However, if flex is the concern, I should think that if you glued/epoxied the lead in place, then no flex would be induced - or rather the change in flex would be limited to the flex difference between spruce and lead (good golly, what would that be?). So there's my half-cent worth (or worthless, as the case may well be). Terry Farrell ----- Original Message ----- > When installing keyleads in new keys, will there be any significant > difference in key flex if you drill the holes all the way through versus > not. Let's assume for arguments sake that the holes are located in the > center of the key. > > David Love _______________________________________________ pianotech list info: https://www.moypiano.com/resources/#archives
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