How about, as the wood dries, it shrinks. Since the fibres of the wood, lie in a line front to back in the key, in the drying the fibres get closer together, so the hole gets smaller, resulting in a tightening around the keypin. John M. Ross Windsor, Nova Scotia, Canada jrpiano at win.eastlink.ca ----- Original Message ----- From: "William R. Monroe" <pianotech at a440piano.net> To: "Pianotech List" <pianotech at ptg.org> Sent: Monday, September 11, 2006 11:46 PM Subject: Re: Sizing Key Mortises (was inconsistent rail pins) > OK, > > I'm also in a cold dry winter climate, and this year I'll do the > experiment with one of the materials of our trade. I'll measure a key now > and over the course of the next year, and see what I find. I have never > experimented to check this phenomena, but by the books, it wouldn't > happen. > > Wood fibers swell with moisture, shrink as they dry. A quick read of a > book like Hoadley's "Understanding Wood" supports this idea, no matter the > wood. The rates vary depending on what cross section of the wood we look > at (tangential, radial, or longitudinal). > > I asked a wood scientist at the University of Wisconsin, Roger Rowell, > about techs suggesting the pin holes in flanges would shrink as they dry. > He said, categorically, no. So, I've always wondered what complicating > factors might be at work here to cause some techs to get these "tighter > when dry" readings. I dunno. > > Let's be clear, I'm not saying tighter frictions can't happen during the > dry season, but my feeling is it is not because, "drying wood swells." > > I'll be measuring.................. > > Regards, > William R. Monroe > > > >>>From my experience out here in Québec (cold & dry winters) the >> keybushings will get tighter with humidity going down, not the opposite. >> If you take measurements of the key width when humid and then when dry, >> the dry key will be smaller than the wet one. So, the mortise will be >> smaller as well. >> >> Marcel Carey, RPT >> Sherbrooke, QC >>> Hi Terry, List, > >
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