How to Do a Mortise & Tenon Joint
- 1). Place the two boards on a flat surface. Use a carpenter's square, and mark the width and length of the mortise and the tenon with a scribing knife.
- 2). Install a brad-point bit with a diameter equal to or slightly smaller than the diameter of the mortise. Bore overlapping holes into the area of the wood that you plan to remove, and use a mallet and chisel to remove the wood. To avoid splitting the wood, start with a chisel equal to or slightly smaller than the mortise, and chisel one end of the mortise first; then chisel along the length of the mortise.
- 3). Clamp the tenon board onto a clamp vise and use a fine-toothed saw to cut the tenon cheeks by lining up the outside of the scribe marks, and cut diagonally along the scribe marks. Clamp the tenon board flat onto the working surface and use a chisel to remove any remaining waste at the shoulder.
- 4). Check for proper fit of the joint by inserting the tenon into the mortise. The piece should fit snugly but not tight enough that you have to force the tenon into the mortise. Use a chisel to pare off any remaining waste. Take note that if you are applying glue to the joint, the glue will swell and make the joint tighter.
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