Recently I began the reproduction of a 17th-century Butterfly Table. The original piece, in the Berkshire Museum in Massachusetts, was constructed with plain, square, flat joints in the top between the center fixed leaf and the outer hinged leaves. While this works well, I want to replace it with a stronger and more beautiful rule joint.
Here is the SketchUp design showing rule joints.
While the rule joint looks to be quite simple, the details are complex, along with the positioning of the special hinges. Here is a dimensioned drawing showing these details. Notice, in particular, that the center of rotation is raised slightly from a position you would expect. This offset is important for a smooth rotation without gaps.
I’ve prepared a set of four short videos (in a Playlist) capturing my SketchUp process of converting the original joints to rule joints.