How to Cut the Right Angles for Downpipes

Raise a ladder against the gutter where the down pipe will be installed to the gutter outlet. Climb the ladder and measure the distance between the wall and the outside of the gutter outlet, using the measuring tape.

Measure the width of the downpipe with measuring tape. Multiply the width of the pipe by two, add the value to the distance between the wall and gutter outlet and add an additional 4 inches.

Lay the pipe flat on the ground, place the measurement obtained in Step 2 along the downpipe starting from the opened end. Mark the measurement onto the pipe with a pencil. Extend the marking around the entire pipe.

Measure the width of the pipe again. Apply this measurement to both sides, above and below, the penciled line and mark the measurements onto face of the pipe. Extend the line across the face.

Measure 1/2-inch below the top line, closest to opened end of the pipe, and above the bottom, furthest away from the opened end, and mark it with a pencil. Extend the lines across the face.

Measure a further 1/2-inch from the top line, mark the line with a pencil and extend it across the face. Turn the pipe on its side and draw a line extending from the freshest top line at an angle to meet the center line that wraps around the entire pipe, it should look like a "\I" shape. Do the same on the opposite side and for the bottom lines, the end result should look like a "\I/" shape.

Cut along the lines with a hack saw until your 1/2-inch away from cutting through. Use a pair of snips to cut the sawed piece out leaving a 1/2-inch flap.

Bend the pipe in 90-degree angle and fit the cut out portions of the pipe together. Rivet the pipe together at the angle. Silicone the angle to seal the open spaces between in the cut.