> You're right, EMC is important only in that it predicts dimensional change. If > you want to know the dimensional change, measure the dimensional change...duhh "Simple" is the part we hustle past looking for the more difficult answer and the shinier tool. > Ron, did you calibrate you're sample using the standard shrinkage/expansion > charts? Nope, I asked the wood directly. Make up a cross grain spruce strip for the meter, maybe a foot long, and another identical one (test piece) just short enough to be measurable with a 6" digital caliper. Make them from the same plank, something of as uniform a grain density as you can find. Make the frame and dial indicator mount and have everything ready to assemble before you start finding the MC and expansion rate of the sample, so you can do all this before the MC in the real piece changes. Measure and weigh the test piece. You don't have a very big sample to work with, so accuracy is important. I used a little reloading scale, and got the weight in grains, but tenths of a gram on a digital scale should be fine enough. Once you have the length and weight of the sample, dry it in an oven at something around 200°F until the weight quits changing. Might take an hour or two. When the weight quits changing, moisture content can be considered to be zero. Measure and record the dry weight and length. The MC% of the strip you'll use for the gage is figured from the data gotten from the test piece as (wet weight - dry weight)/ dry weight * 100. The dimensional change rate is calculated from the same data as a 0.001" per 1" per MC%, and the gage strip is anchored in it's frame at an appropriate distance from the end so that it will respond at 0.010" per MC% over it's length. Set the dial indicator in the frame so the MC reading corresponds to what your test data said, and you're there. Oh, I capped the strip with a strip of maple where the dial indicator plunger rides, so it wouldn't indent significantly over time. > Your gizmos officially qualify to to be referred to as > elegant....congratulations, and thanks. > > Jim I You bet. I want to see the new gage when it's built. <G> Ron N
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