One Joint. Make It Square.

Start with flat stock and straight, square edges. Mark the reference face and edge on each piece, and make every measurement from those marks. Verify your square against a known straight edge before trusting it. An error in the stock carries into the joint; it is easier to correct now than after the pieces are glued.

Lay out the joint on scrap first and mark the material to remove. Secure the piece and keep hands behind the cutting edge. Saw on the waste side of the line, then pare cautiously with a sharp chisel. Remove small amounts and test the fit repeatedly. A practice half-lap is an exercise in control, not a race to make two boards meet.

Bring the pieces together without adhesive and check both the fit and the angle. Do not force a tight joint with a hammer; find the high spot and correct it. Follow the adhesive instructions for surface preparation, clamping, and curing. This practice joint is not a substitute for a tested design where furniture, structures, or equipment must carry a load.