US 4,019,298 · Granted 1977-04-26
The Dovetail Joint That Holds Beams Solid Without Nails
Imagine fitting two pieces of wood together like a puzzle where the shapes lock perfectly into each other. This patent describes a special interlocking joint where a beam slides into a joist with ridges and cavities that grip from multiple angles, holding everything rock-solid without any wiggle room.
The plain-English version
What it protects
The claim covers a specific method of joining a beam to a joist using a dual tapered dovetail-shaped mortise (a cavity cut into the joist) paired with a matching dovetail-shaped tenon (a projection on the beam). What's protected here is the particular geometry of the ridges and laterally oriented cavities on both the mortise and tenon that create a frictional interlock in multiple directions. The patent locks down the design where these opposing forces work together to secure the connection without fasteners.
Why it matters
This patent represents an alternative to traditional nailed or bolted beam-to-joist connections in furniture and timber construction. By relying on geometric interlocking rather than metal fasteners, the joint could offer a cleaner aesthetic, potentially easier assembly, and a connection that works equally well whether the joint is oriented horizontally, vertically, or at any angle. The rigid frictional lock without play means no future loosening or creaking, important for structural integrity.
Real-world use
You'd encounter this joint in high-end wooden furniture like tables, benches, or bed frames where a beam needs to connect to a supporting joist while remaining completely stable and seamless.
Original USPTO abstract
A dual tapered dovetail shaped mortise is formed within a joist to receive a dual tapered dovetail shaped tenon extending from a beam. Laterally oriented cavities are disposed within opposite faces of the mortise to receive correspondingly configured ridges formed integral with the mating tenon. The resulting frictional interlock between the mortise and the tenon created by two forces acting in opposition to one another rigidly secures the beam to the joist without play therebetween. The ridges, mating with the corresponding cavities, affords use of the resulting joint in any plane from horizontal to vertical without danger of separation.
Patent details
- Publication number
- US 4,019,298
- Filing date
- 1974-11-04
- Grant date
- 1977-04-26
- Assignee
- Johnson Iv John J
- Inventor(s)
- JOHNSON, IV; JOHN J.
- CPC class
- F16B5/0052
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