This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Yesterday, January 9 made one week that my three flanges were exposed to = 100% humidity. I inserted the same 1/8" polished drill rod into each. = All were a little tighter than after two days. It was very difficult to = insert the rod into all three flanges. It appears clear to me that the = center pin hole in piano action flanges get smaller (decrease in = diameter) as the reletive humidity (RH) increases. I will let them dry = at 50% RH for a week and see whether they are the same tightness as when = I first drilled them. I will then dry them in a low-RH environment for a = week and see what happens. I'll post in a week or so. Any comments? Terry Farrell Piano Tuning & Service Tampa, Florida mfarrel2@tampabay.rr.com ----- Original Message -----=20 From: Farrell=20 To: pianotech@ptg.org=20 Sent: Friday, January 05, 2001 10:31 PM Subject: Results are In! Re: moisture in wool or wood. Tuesday, January 2, I started my hole in wood experiment to see if a = hole will get smaller in diameter or larger with increased humidity. = Rather than drilling holes in wood that may or may not reflect what = happens with an actual flange, I took three old flanges lying around my = shop. One was an grand damper flange, one an upright hammer butt flange, = and one was a grand hammer shank flange. All were likely in the 40 to 80 = year old range, and all had been sitting in my shop in 40% to 50% = reletive humidity (RH) for months. I drilled out the flange bushings = with a 1/8" drill in my drill press, being sure to keep things square. I = cut three pieces of 1/8" drill rod for center pins. I filed the ends and = polished the rod/pins so that they were nice and smooth. All three = rods/pins fit into the flanges real easy by hand, but had no slop. My = pinky could easily push them in and out with little effort. Since Tuesday the flanges have been sitting on a little plasitc = platform in a tupperware box with a little water in the base. The = flanges have not touched the water, but rather have been exposed to 100% = humidity for three days. The center pin for the damper flange fits = noticeably tighter, but was no trouble pulling it out with fingers. The = butt flange was tighter yet. And the grand hammer shank flange was very = tight, I could just barely push it in and get it back out - VERY tight. It would appear to me that the hole in a wooden flange decreases in = diameter with increasing humidity. Am I wrong?=20 I'm gonna wait a whole week and then check them again. After that I = will dry them out real good and slow and check them under very dry = conditions. Terry Farrell Piano Tuning & Service Tampa, Florida mfarrel2@tampabay.rr.com ----- Original Message -----=20 From: Donald Mannino=20 To: pianotech@ptg.org=20 Sent: Monday, January 01, 2001 10:56 PM Subject: Re: moisture in wool or wood. Terry Farrell wrote: I have heard/read this many times, so I suppose it is true. But, = intuitively, it makes no sense to me. If you drill a hole in a piece of = wood and expose it to high humidity, the wood will swell - and swell = much more across the grain (perpendicular to the grain direction) than = with the grain. So why doesn't the hole tend to close a bit - on the two = sides of the whole where the tangents are parallel to the wood grain. Because the whole piece of wood swells, and the hole becomes larger = along with the piece of wood. As I wrote in my last post, imagine the = plug of wood which used to be in the hole. The hole behaves the same as = the plug of wood that was taken out. Do the hole and rod test. Just pick a small piece of maple or = something, soak it in water for a while, then drill a hole in it with a = spare drill. After drilling, put the drill back in the hole, then dry = the wood in the oven! That drill will be really nasty tight in the = hole! You'll have to soak the wood again to get it out. There are some exceptions to this behavior: 1. In some situations the surface fiber swelling in the hole exceeds = the change in shape of the wood. Key balance holes are examples of = this, where high humidity sometimes tightens the fit. The wood = thickness is small, and the wood fibers are large and sometimes made of = more reactive wood. 2. Cross-laminated wood is more dimensionally stable, and the = surface fibers will again have more affect on the hole size than the = dimensional changes of the wood. This is what happens in pinblocks. 3. If the hole was made by compression of the fibers instead of by = drilling and removing wood (like with a nail) then the grip on the nail = is tighter during humid times. All surface fiber effect, no hole to = swell. Don Mannino RPT ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/4f/40/04/19/attachment.htm ---------------------- multipart/alternative attachment--
This PTG archive page provided courtesy of Moy Piano Service, LLC