Coming to this thread a bit late, with a couple comments and questions. Gene, I went 'round robin hood's barn on this accurate, trustworthy mc readings question. You might check archives January '08 under "moisture meters?" for more of the discussion. As a result of that thread, I ended up building a version of Ron's direct reading dial indicator gizmo...and I love it! A couple of points I learned as I worked this through: 1-Many of us were complaining about the inconsistent and generally weird results achieved by oven drying. That's because oven drying is defined as between 215-217 deg f....a pretty narrow window. Before I calibrated Ron's gizmo, I experimented with trying to get consistent results in the oven. The answer was to be fairly anal about the oven temp. My oven's thermostat is out to lunch, so, not having a lab oven, and being generally cheap, I calibrated the oven by: -first taking a plumbers water testing thermometer's probe and placing it in boiling water, marking where boiling 212 was on the dial. -then took a very small glass vial, like a dropper bottle, filled it with vegetable oil, put the plumbers thermometer in it and put it in the oven. When plumbers thermometer read just a hair over 212 in the oven marked the oven dial and waited for the temp to be stable. For me this got things close enough for jazz . 2- Hoadleys expansion/contraction/mc change formulas imply that wood's expansion rate is linear. Expansion rates are in fact not quite linear! That means the meter is best calibrated and read at or reasonably near the mc you are shooting for. That's really not a problem, because we only really care when the board has achieved that target 6.5% or whatever your shooting for. 3-Hey Jude, the gizmo saves having to invest in highly accurate hygrometers (yeah, right) for your hot box. I've been burned enough times by fancy expensive measurement devices to return to my pre-industrial roots...just stick Ron's gizmo in with board and read the dial indicator. A question for Ron...in your tall skinny hotbox, what is your heat source and where is it located in the box. My box is similarly shaped, but I don't like putting the heat source at the obvious place, ie the bottom, right up close to the bottom of the board. -- Jim Ialeggio www.grandpianosolutions.com Shirley, MA (978) 425-9026
This PTG archive page provided courtesy of Moy Piano Service, LLC