Cutting Long StripsRotary cut the fabric strips required for your project from the squared-up side. For example, if you need a 3" wide strip, align the 3" mark on the ruler with the left edge of the fabric. Align a horizontal line near the bottom of the ruler with the fold. Use a rotary cutter to cut along the right side of the ruler..
Before you make each cut check to be sure that the left and bottom edges of the fabric align with vertical and horizontal markings on the ruler. If they do not, square up the end again before cutting more strips.
It isn't unusual for the leading edge of fabric to become out of square after several cuts, so you're not doing anything wrong if you must square it up occasionally.
Check Strip AccuracyOne way to make sure your edge is square is to open a rotary cut strip to its full width and look at the area near the fold. If the strip has a bend in the middle the fabric's left edge is no longer square.
Rotary Cutting Segments from StripsPlace your rotary ruler near the right end of a cut strip, aligning a horizontal rule with its lower edge. Cut along the right edge of the ruler to square up the end of the strip.
Turn the strip around and cut segments from its left edge in the same way you cut the original fabric strips, aligning the strip with markings on the ruler as required for each shape. See Rotary Cutting Patchwork Shapes.