Seasoned woodworkers know that to ignore wood movement is a sure path to heartache. A drawer cut too wide will expand in humid weather and will almost certainly stick; a panel cut too narrow may shrink and show unsightly gaps. It's not hard, however, to figure out exactly how much a board will expand and contract, as long as you know the wood species, the current moisture content, the grain orientation, the width, and the expected highest and lowest moisture content for your area. Contributing editor Christian Becksvoort explains two methods for calculating wood movement. Equipment includes a moisture meter, a calculator, a ruler, and a dial (or vernier) caliper. One method uses a Wood Movement Reference Guide, the other a chart and formula.

From Fine Woodworking #187