How to Make a Garden Windmill

Cut a 28-gauge or heavier sheet of metal to a square measuring 18 inches or greater using tin snips. Drill a hole in the exact center of the sheet of metal using a ¼-inch drill bit.

Tie one end of an approximately 12-inch-long piece of string to a grease pencil. Feed the other end of the string through the hole in the center of the sheet metal until 9 inches of string remains between the sheet metal and the pencil. Tape the free end of the string to the back of the sheet metal.

Hold the pencil upright and, with the string pulled taught, draw a circle around the hole drilled in the sheet metal. This will give you an 18-inch-wide circle. Remove the tape and string. Cut out the circle using tin snips.

Draw a line through the center of the metal circle that bisects the circle in half, using a grease pencil and a ruler. Draw another line to divide the circle into quarters. Draw two more lines through the center of the metal circle to divide each quarter in half. Cut along each line using tin snips, stopping the cut 2½ inches from the center of the circle. You should end up with a circle with 8 equally sized fan-shaped blades each measuring roughly 6½ inches long.

Draw a 5-inch-wide octagon in the center of the metal circle with the grease pencil by connecting the inner ends of each blade’s cut lines with the cut lines next to them. Score the metal alone the octagon’s lines using a utility knife. Flip over the metal circle. Measure and mark a point along the left edge of each fan blade that is 5 inches from the outer edge of the blade. From this point, draw a line angling back toward the right interior corner of each blade. Score the metal along the angled lines using a utility knife.

Lift each blade toward you, folding it gently along the first set of lines you scored. Identify these score lines by the octagon shape they form on the metal circle. Stop each fold at approximately a 45-degree angle from its original position. Flip the circle over carefully. Bend each blade back toward you along the second set of score lines. Identify these score lines by the angled line they make across each blade. Stop the folds at approximately 45 degrees from their original position. The double bend in the blades create a pinwheel effect to help catch the wind.

Cut a 5-foot length of 1-inch diameter wood dowel using a hand saw. Cut one end of the dowel to a point using a hand saw. Cut a second piece of 1-inch-diameter wood dowel to a length of 12 inches. Draw a line on one end face of the 12-inch dowel that bisects the circular dowel in half. Secure the dowel in a vise and cut into the marked line with a hand saw, creating a 2-inch-deep slot into end of the dowel.

Cut a trapezoid shape from the sheet metal with two parallel sides measuring 7 and 3 inches and two angled sides measuring approximately 8 inches. Slide the short end of the trapezoid-shaped metal fin into the 2-inch-long slot in the 12-inch dowel. Drill two evenly spaced holes through the side of the dowel, through the fin and back out through the other side of the dowel, using a drill bit slightly wider than the diameter of a 1¼-inch-long bolt. Secure the fin to the dowel using two 1¼-inch bolts.

Coat all the wood pieces with exterior latex paint and all the metal pieces with metal paint, using a paintbrush. Allow the paint to dry.

Grasp the 12-inch dowel with the fin attached, locate the end face of the dowel with nothing attached to it, and mark a point on the center of the end face. Drill a pilot hole into the mark, using a using a drill bit slightly narrower than the diameter of a 2-inch screw. Thread a washer onto a 2-inch screw, then thread the metal circle with the blades onto the screw, and then thread a second washer onto the screw. Drive the screw into the pilot hole, but not so tightly that it stops the metal blades from spinning freely.

Drive the pointed end of the 5-foot dowel 12 inches into the ground, using a rubber mallet. Check for level using a carpenter’s level. Drill a pilot hole down through top end of the dowel, using a drill bit slightly narrower than the diameter of a 2½-inch screw.

Find the windmill’s center of gravity by balancing the side of the 12-inch dowel on your finger. Mark the center of gravity with a pencil. Drill through the dowel at the mark using a drill bit slightly wider than a 2½-inch screw. Ensure that the fin is oriented perpendicular to the ground when drilling. Slide the screw through the 12-inch dowel and screw it into the pilot hole in the top of the 5-foot dowel, but avoid screwing it in so tightly that it stops the windmill from pivoting freely.