It's raining here, finally. We've been in a dry spell lately, and the only rain that we saw for a couple of weeks was dripping of of us as we dealt with near record heat. My student, Mark, and I sweated our way through a continuous arm and learned a little something about wood and humidity.
We pulled Marks stretchers from the kiln (opening the kiln was a punishment in and of itself) and started to do my normal assembly procedure. The only problem was that in the short time that it took us to drill the legs, the tenons swelled .005" or more and the first joint that we drove home made a nasty split down the side stretcher. Granted, the joint may have been a bit tight in the first place, and the mortised piece was drier than usual, but this was ugly.
I'd seen this before, the twisting that we applied to free the tenon threatened to turn solid wood into a rope of separated fibers. It's something to see a complete spiral fracture in hard maple.
So I decided to take the other route, split the mortised piece, thereby saving the tenon, and turn a new side stretcher.
Sometimes getting in a pickle leaves the student more informed and a bit more comfortable with the notion that we all get in a bind sometimes and it isn't the end of the world, or chair.
Below are a couple of photos that were requested by blog readers. The arm below shows that the continuous arm bend is about 72 degrees. With a 7/16" arm, it works out fine.
And Greg, here is the hoop pattern for the childs balloon back. I'll be teaching this chair again in October down at Highland Woodworking.
I do my best to keep up with reader requests, but please forgive me if my schedule delays or doesn't permit my immediate response. Good luck.