If you're ever stuck with a piece of lumber that's too short for your project, there's a remedy for your predicament. A second piece of wood can be used to extend the length. Two processes can achieve that extension: lap joining and dovetail joining. Lap Joining Lap joining involves cutting two work pieces so one piece laps over the other. Materials: Two pieces of wood (of equal width and depth but of any length)
Pencil
Ruler
Table saw
Wood glue
Drill
Wood screws
- Using a pencil, trace the lap on each piece of wood. The lap should be half the thickness of the wood and two to four times as long as the wood is thick. It's essential to measure so that the laps on both pieces of wood have identical dimensions.
- Set a table-saw blade at exactly half the thickness of the first strip of wood (figure A). In this case, the pieces of wood are 2" by 4" lumber, whose thickness is actually 1 1/2", so the saw blade is set at a height of 3/4".
- Pass the wood through the blade, starting at the innermost edge of the lap (figure B).
- Make as many passes as needed, working the blade toward the end of the work piece (figure C). Eventually you'll create an L shape in the wood.
- Repeat steps 3 and 4 for the second piece of wood. The two laps should be a perfect fit (figure D).
- Fasten the joint with glue. Secure the joint with wood screws.
Dovetail Joining Like lap joining, dovetail joining holds two pieces of wood together to act as one piece. The difference is in the shape of the joint. Materials: Two pieces of wood (of equal width and depth but of any length)
Pencil
Ruler
Table saw
Jigsaw
Wood glue
Drill
Wood screws
- Measure the width of the first piece of wood. In this case, the lumber is 2" by 2", so the actual width is 1 1/2". Use a pencil and ruler to mark a spot at one edge of the end that is one-third the total width of the wood--in this case 1/2" (figure E).
- Working on the side closer to the mark made in step one, use the ruler to mark a spot on the long edge of the wood that is three times the total width of the wood (figure F). In this case, the mark should be 4 1/2" from the short edge.
- From the point marked in step 2, position the ruler perpendicular to the wood, and mark a spot two-thirds the width of the lumber (figure G). In our example, that would be 1", as the wood is 1 1/2" wide.
- Using the ruler as a straightedge, draw a line between the marks made in steps 1 and 3 (figure H).
- Repeat steps 1 through 4 for the second piece of wood.
- Adjust the height of the table-saw blade to two-thirds the width of the wood. Adjust the table-saw fence so the work piece hits the blade at the mark made in step 3 (figure I).
- Hold the two pieces of wood together so that the pencil tracings on both face you. Send both pieces through the blade at the same time (figure J).
- To make the long cut for the joint, hold the two pieces of wood together so their pencil marks face up. Send the wood through a band saw, guiding the blade down the pencil line (figure K).
- Fasten the joint with glue, then secure it with wood screws.
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