The Arrowhead block is a very simple block to sew as long as you are careful to sew SCANT 1/4" seams, you cut accurately and you match seams carefully. This block finishes at 8 ½”. If you are making the scrappy version, layer two contrasting pieces of fabric, right sides together (RST), starch and press. Then cut an 8” square from the stack. Repeat with other scrap fabrics so you have sets of two 8” squares for each block. For the two-fabric version, layer the two contrasting fabrics RST, starch and press. Cut sets of two 8” squares for each block. Pin the stacks so the fabrics don’t shift. You can click on the photos to enlarge them.
Measure 2” down from the top right corner of one set of squares. Sew a SCANT ¼” seam down the right side, pivot ¼” from the bottom, and sew across the bottom to the end. Backstitch at the beginning of the stitching.
Turn the square so that the bottom of the square is now at the top. Measure 2” down from the raw edge at the top right corner of the square. Sew a second SCANT ¼” seam down the right side, pivot ¼” from the bottom, and sew across the bottom to the end.
Lay one of the sewn triangles on top of the other, with the sewn and raw edges matching. Wrong sides of the top fabric should be facing up in both triangles.
Cut a 2” strip along the left sewn side of the triangle. Without moving the pieces, cut another 2” strip from the other sewn side of the triangle. See photos above right and below right.
Lay out the sewn pieces and the triangles as shown in the photo below left. Notice that opposite fabrics touch each other on all adjacent sides. Pinwheel the seam allowances of the small center 4-patch by removing the two or three stitches within the seam allowance at the seam intersection. See photo at right below.
The pieces are sewn back together on the diagonal. See photo at left below. Press seam allowances as shown in the photo at right below. Sew the three diagonally pieced sections together, matching seams. Press the seams as shown in the photo below right.
Photo below shows detail of seam allowance pressing directions.