Visible screws or nails greatly detract from the appearance of cabinets and other furniture made from plywood, and professional woodworkers avoid them when joining sheets together. A procedure for joining plywood corners that avoids visible fasteners and isn't too complex involves gluing and screwing braces to the plywood edges and using them to screw the sheets together from inside or underneath. Braces are easily made by ripping hardwood lumber into 1-inch strips, which can be then cut into appropriate lengths. The plywood corners look best if the sheets are first mitered to a 45-degree angle on a table saw.
Things You'll Need
- Table saw
- Hardwood lumber
- Drill bit, 1/4-inch
- Carpenter's glue
- Wood screws, 1 1/4-inch
- No. 2 Phillips bit
Cut a 45-degree angle on one of the sheets of plywood you wish to join to another. Measure the width of the sheet and set the fence that distance from the far edge of the blade. Adjust the blade angle to 45 degrees, then move the fence back toward the blade at a distance equal to the thickness of the plywood. Run the plywood through the saw with the face that will be visible, facing up, to make a mitered edge.
Miter the edge of the other sheet to form the corner in the same way.
Rip a strip of 1-inch by 1-inch stock from spare hardwood lumber, and cut the strip into 3- or 4-inch lengths to make braces. Drill two 1/4-inch holes through one face of each brace, then turn each brace 90 degrees and drill two more holes through the perpendicular face. The holes in the perpendicular faces shouldn't intersect.
Lay one of the plywood sheets flat, with the inside surface facing you. Spread glue on one face of one of the braces. Align the brace with the inside edge of the miter near the top of the plywood, and use a drill and a No. 2 Phillips bit to screw it in place with two 1 1/4-inch wood screws.
Screw a similar brace to the bottom of the sheet, aligning it with the inside edge of the miter. Screw one or more braces between the top and bottom one, depending on the length of the sheet of plywood. If the sheet is short, you may only need the top and bottom braces.
Spread glue on the side of each brace facing the joint. Align the mitered edge of the second sheet of plywood with that of the first, and drive screws through the perpendicular holes in the braces and into the plywood. When you tighten the screws, they will draw the sheets together. Let the glue dry before you put any pressure on the joint.
Tips & Warnings
- Use slightly longer screws if you join 3/4-inch or thicker plywood. The idea is to get the maximum holding power without driving the screws completely through the plywood.
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