Creating the Rule Joint
I’m again faced with designing and making the rule joint for this Shaker table. The rule joint is the very functional, structural, and beautiful connection of the table leaves – to allow the folding of the table.
Here is the table with two folding leaves.
This joint is tricky, and requires my review of the details and procedure every time. Of course, it helps to work through the process in SketchUp before moving into the shop. Then you know you’ve got it right.
So in the following video, I’ll show how to make this joint in SketchUp.
Whether you are in the shop or in SketchUp, the first thing you need to know is the size, and detail design of the rule joint hinges. Hinge suppliers usually provide some details, but it is best to buy the hinges to have on hand to verify the details.
I started with a scanned image of a particular hinge from Horton Brasses catalog number H-150. Then I traced over the shape of the hinge and created a full scale model including the exact thickness.
The model of the hinge is built with separate components for the two halves. In this way you are able to rotate the hinge to have the fold-down configuration as well.
The next step is to place the hinge on the butted-up table top with the leaf. Note that the thickness of the hinge is a very important variable to know. This establishes the center of rotation and the geometry for the rule joint on the edges of the Top and Leaves.
The next steps are to do the geometry changes to the edges of the Top and the Leaf. To begin the geometry changes, the Circle Tool is positioned at the rotation center of the hinge.
The remaining work is with the Push/Pull Tool with some erasure clean-up. Also, the underside of the table leaf and top need to be routed out for the body of the hinge that will be flush on the bottom surface.