Woodworkers often require joints that are mostly permanent, but may need to be taken apart to move the piece in the future. A threaded insert, known as a T nut, can be used to supply this type of joint. The metal sleeve is inserted into a hole in the piece on the bottom of the joint, so that a machine screw can be threaded into the wood.
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Select a size of T nut that will fit in the material you are using for your joint. Keep in mind that T nuts have a round disk flange that needs to be seated flush with the face of the material, so the width of the overall hardware will be important, it must fit within the thickness of the edge or face it is being inserted into. Select a bit the size of the outside dimension of the insert sleeve. The proper bit size is typically mentioned in the instructions that come with the hardware. Visually match them up if needed.
Overlap the two pieces to be joined, or position the hardware you are mounting, depending on the application. Align everything as it will be when the T nut is in use. Clamp the pieces in place and use a drill press or cordless drill to drill through both pieces, if you are overlapping two pieces of wood, or mark the screw hole through the hardware and bore the wood. Set the drill on high speed and do not force the bit with more than light pressure to maintain a clean hole with no splintering. Keep the drill perpendicular to the face of the material.
Blow the dust from the hole with compressed air and slide the T nut in to check the fit. Follow the instructions that came with it to tap it home. Usually, the nut is driven home with a hammer. Then the machine screw is threaded into the sleeve and tightened until the flange is flush with the material and the pointed grips around the edge are snugly seated into the wood. This step is essential to keep the insert from pulling out when you loosen the screw.
Using the T Nut
Align the top piece of your joint, or position the hardware. Insert the screw through the top piece, or hole in the hardware and twist it clockwise to fasten the two parts together using a screwdriver. Resist the urge to use the drill, overzealous tightening will cause the T nut to fail. To release the parts, use a screwdriver to turn the screw counterclockwise until it is removed from the T nut, then move the parts. The T nut can be reused indefinitely, as long as it is tightened and loosened with care.