How to Cut Shelves With a Circular Saw

Latch a tape measure's tang onto the end of a piece of shelving material. Stretch the tape across the length of the shelving material and use the pencil to mark the desired length of the shelf. Lay a carpenter's square's large side, called the body, over the pencil mark and butt the small side of the square, called the tongue, against the shelving material's edge to align the square's body perpendicularly across the shelving material's face.

Run a pencil along the edge of the square and through the pencil mark to layout a cut line across the board. If you must rip the shelving material to reduce its width, draw the tape measure across the shelving material's width at both ends and use the pencil to create corresponding marks at both ends of the board. Stretch a chalk snap line between the corresponding marks and snap the line to layout a rip cut line across the length of the shelving material.

Attach a rough circular blade to the circular saw to cut utility grade materials or a finish blade to cut finish quality materials. Place the shelving material on top a flat, stable surface, such as a pair of sawhorses or a workbench. If the cut mark rests near the edge or end of the material, hang the cut mark over the edge of the work surface.

Support cuts that fall near the material's center from both sides. If you fail to adequately support a cut, the material might fold inward during cutting, pinch the saw blade and cause personal injury or damage to tools and materials.

Place the edge of the circular saw's baseplate onto the edge of the shelving material. Align the saw blade with the cut line, activate the saw and slowly guide the blade through the cut line to sever the waste portion of the shelving material from the finished shelf. Ask a helper to stabilize and support large, dangling portions of waste material from beneath; these portions often interfere with cutting or pinch saw blades.