Q. We are looking to make some legs that need to be as strong as possible. What characteristics should we be looking for?
A. First and foremost, strength in wood is basically a function of the wood’s density. The higher the density, the stronger the wood. So look for a dense species.
(Special note: Within a species, there can be some pieces, such as very slow grown oak, that are low in density and a very weak; avoid such unusually light wood for the species.
Other factors that affect strength include moisture content (drier is stronger); knots and holes, especially when near the edge; decay including the early evidence of decay before the wood actually gets soft; and splits, checks or cracks. Also important is the slope of grain. This slope is determined by noting the direction of a split. Under magnification, the lengthwise direction of the wood fibers that run vertically in the tree should run parallel to the long axis of the wood product. A slope of grain of even 5 degrees can reduce the strength over 25% at times.
Of course, if you need a stronger piece, you can make it larger. In some cases, twice as big can mean four times more strength.
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