The Tenon Lok™ Joinery System from Rockler Woodworking and Hardware eliminates the seasonal impact of wood expansion and contraction on joints. Two spring-action blades on the cutter flare outward when it’s depressed, creating a dovetailed mortise. The system’s Wedge Ring fills the mortise with a similarly shaped tenon. The sharp-edged ring rests in the flared mortise and sinks into the tenon as the round tenon is driven into place: the tenon expands to fill the mortise. A half-inch Tenon-Lok Cutter sells for $18.99; they’re available in other sizes as well. A 12-pack of Tenon-Lok Wedge Rings starts at $4.99 for the half-inch.