|Project by Loren||posted 05-03-2013 03:08 PM||1755 views||3 times favorited||9 comments|
I joined the corners with sliding dovetails to ensure the boxes stay square and stay together even as termites and contact with dirt consumes the wood. The wood won’t be chemically treated because they will be used for growing food.
You might think you could just nail or screw the corners together, but as the wood decays screws will lose their grip, especially in soft woods. Screws and nails driven into the ends of a board have little holding power over time. The mechanical lock of the dovetailed corners prevents the corners from spreading in either direction. It is laborious to do it this way and requires considerable skill, but the strength and squareness of the joint makes it worth the trouble here.
In doing the sliding dovetails I do not think I would do it that way again. A through mortise and tenon joint would be easier to put together, though more time to cut. The problem with the sliding dovetails is that it’s hard to fit them well in wood so soft. The short “tusk” on these boards meant I had some short grain breaking off when I glued and hammered/clamped the dovetails closed. The glue swelled the joints a little and started to set too fast as well.
The broken off “tusk” parts were reattached with glue and I put brad nails through them for good measure.