Everyone Needs a Moisture Meter
New meters are precise and cheaper than ever, leaving you no excuseSynopsis: Knowing how much moisture is trapped in a board helps you during the milling process, when fitting parts, and even when making repairs. And the easiest way to determine this factor is to use a moisture meter. Contributing editor Roland Johnson tested a range of meters and decided that the pinless variety was the best choice for woodworkers. In that category, he tested seven meters for accuracy and consistency, using them in thick and thin lumber, narrow and wide stock, and in roughsawn lumber. When he was done, he not only knew the moisture level of every piece of lumber in his shop, but he also knew which meters he would recommend.
Wood movement is one of the most perplexing situations for woodworkers. Increases or decreases in moisture can warp panels, crack tabletops, delaminate glueups, loosen or split joints, and generally wreak havoc.
Knowing how much moisture is trapped in a board helps you during the milling process, when fitting parts, and even when making repairs. It’s essential to know when the moisture content (MC) is low enough in a pile of rough lumber to start milling it to size (below 12%, depending on the region and season). If the wood continues to move after milling, you’ll have finished parts that warp and cup. You also need to know that all the boards for one project have the same MC, which helps ensure that movement occurs at the same rate in all the parts.
You can determine the MC of lumber using a mathematical formula, but it’s not easy. You need to cut a section of the board, weigh it, dry it in an oven for a period, weigh it again, then put it in the oven and repeat until the board stops losing weight. Finally, you have to dig out a calculator and punch in some numbers. The process can take a couple of days— not very convenient.
A much quicker way to monitor MC is to use a moisture meter. According to our surveys, most FWW readers don’t own one. That’s a shame, because these tools can help any home-shop woodworker avoid the damaging effects of wood movement in a project. And today’s moisture meters are more affordable than ever.
For this article I started by testing a whole range of meters, both pin-type and pinless, from bargain brands to high-end models suitable for a lab. Many of the expensive models simply offered more options than most home shops need, with no more accuracy. So I pared down the list to meters under $200—a good entrylevel price point. After using both types, I concluded that pinless are the best choice for home-shop woodworkers. I’ll explain why, and compare five pinless meters.
From Fine Woodworking #210
Online Extra: Printable EMC Chart
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