Mitered Bridle Joint
While trying to salvage a canvas stretching frame that must be more than 100 years old, I encountered a miter joint I’ve never seen before. What is it called?
—Roy Gaines, Toccoa, Ga.
One of our joinery sources referred to a similar joint as a mitered mortise-and-tenon, Roy, or you could call it a twin mitered bridle joint. But the company that pioneered it, Tara Materials, calls it an interlocking tongue-and-groove joint. The joint was developed in 1875 by founder E.H. Friedrichs for the company’s canvas-stretching frames. (It even was illustrated in a 1907 Fredrix catalog shown above.)
Today’s version, shown below, hasn’t changed much from the original. The tongues in both pieces slide into corresponding slots, creating a frame that resists torquing out of shape from the stress of stretched canvas. The joint also provides plenty of surface grain for a solid glue bond, unlike a simple, unreinforced mitered frame, with its end-grain gluing surfaces.