Cutting miter on wide plank

[Maurice Arney]

After googling images of wood countertops, I'm starting to like Jack Caldwell's idea of using a butt joint.

[John Gulick]

Hand held skilsaw

[Gary Kman]

It's not a question of the joint might open up. A miter in wide solid wood is guaranteed to to open up. While its open stuff will build up in the crack. In the summer when humidity increases each board will get wider. Since the joint is butted on the inside corner neither piece can move there so the outside has to open up and open a lot. Then winter comes and the width decreases. The crack can't close on the gapped side with all the failed fasteners and debris holding it apart so the long point has to pull apart. Try to make it behave with lots of biscuits, steel truss plates or anything else or and the boards will split. They have to. Look at all the work that has gone into doors for hundreds of years to minimize dimension change. They didn't do all that work using hand tools building a frame with floating panels to get exercise. Search for joint shrinkage for pictures.

[Maurice Arney]

Hand held skilsaw

Yep! with straight edge and a couple of clamps.

[Maurice Arney]

It's not a question of the joint might open up. A miter in wide solid wood is guaranteed to to open up. While its open stuff will build up in the crack. In the summer when humidity increases each board will get wider. Since the joint is butted on the inside corner neither piece can move there so the outside has to open up and open a lot. Then winter comes and the width decreases. The crack can't close on the gapped side with all the failed fasteners and debris holding it apart so the long point has to pull apart. Try to make it behave with lots of biscuits, steel truss plates or anything else or and the boards will split. They have to. Look at all the work that has gone into doors for hundreds of years to minimize dimension change. They didn't do all that work using hand tools building a frame with floating panels to get exercise. Search for joint shrinkage for pictures.

You are right. I think a "same direction" butt joint is a much safer bet.