WD: Wood Movement

WD_Movement_Opener

A number of years ago a really bad movie about the revolutionary war called “The Patriot” staring Mel Gibson hit the big screen. It was bad on so many levels that I can’t even begin to explain it. However, the good guys, as you know, win, so I watch it whenever it’s on. The reason I mention it is that throughout the movie, Gibson attempts to build a Windsor chair – a rocker actually – without much success. Allowing the fact that there were no period-Windsor rockers slide (as I said, bad movie), I cannot for the life of me figure out how he could turn all those parts, assemble them into what was, I have to admit, a pleasing looking chair and have it explode the moment he sat on it! Hopefully, Gibson is a member of 360 Woodworking. If so, maybe we can help him.

Windsor joinery – at least the way I do it – is simple. It’s based on the how wood moves, and how it was processed and handled in the period. Wood-drying kilns are a relatively new item. Woodworkers in the period worked with air-dried lumber, which meant that in my neck of the woods in Pennsylvania, there was anywhere from 8 percent to 10 percent or more moisture content, depending on the time of year. A typical house environment in Pennsylvania in the 18th century would range from 90° and 75 percent humidity in summer, to 50° and 25 percent humidity in winter. Compare that to today’s house environment of 73° and 50 percent humidity all the time!

Tenons & Sockets

We modern woodworkers are so spoiled. The old guys expected movement and shrinkage (wood shrinkage that is, not winter camping-type shrinkage), and they accounted for it in their joinery. And in the case of a Windsor, they took advantage of it – there is evidence that some period chair makers turned parts in green wood right among the trees on lathes powered by bent saplings. I rather prefer my nice warm shop. (I do sometimes scatter leaves around and play bird sounds just for the effect though.)


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One thought on “WD: Wood Movement

  1. I love getting this kind of info! And knowing where I can find it again if I’ve forgotten the details.

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