You will be assembling the blocks one row at a time. Starting in the bottom left corner of your design. When you start, work with only one block at a time. Once you understand the construction, you can work with a whole row. To work with a row, take the first block off the wall and, keeping the fabrics for each block together and overlapping, place the block onto a carrier (butcher paper square, paper plate, paper towel or sheet of typing paper). As you pull each block off the wall and place it on its carrier stack the block laden carrier on top the previous block and carrier. Stacking the blocks on their carriers keeps the block pieces secure and makes the row easy to carry and separate for working on. If you are concerned about losing track of where the block go, number the carrier starting from the left side. Replace the block on the carrier when it’s complete and return it to the proper location based on the number on the carrier. Rotate the block to get the fabrics into the correct location to complete the pinwheels.
It is necessary to keep the pieces for each block in the correct relation to each other. You cannot switch the fabrics around or the pinwheel fabrics will no longer mate to the adjoining blocks to form pinwheels.
As you sew you will assemble the block pieces working clockwise. The slanted edges of the pinwheel fabric are bias cuts. Be careful in sewing and pressing these edges so they aren’t distorted. Once the block is complete there are no exposed bias edges.
Place the center square on a wedge with right sides together and edges matching as shown.
Sew halfway along the square’s edge using a 1/4″ seam, leaving the lower half of the seam open as shown. This is a partial seam which will be completed at the end of sewing the block. This is the only partial seam in the block. All other seams are sewn completely.
As each pinwheel is added, press the seam toward the pinwheel fabric. For this partial seam, press only as far as the seam has been sewn.
Working clockwise, set the assembly down on the next wedge right sides together and sew the entire length of the edge as shown. Alternately, you can set the assembly down where it goes in the block and flip the next clockwise wedge into place on the assembly as we do with the remaining pinwheel wedges.
Press the seam toward the pinwheel fabric being careful not to press the unsewn portion of the previous seam.
Lay the assembled parts down where they go in the block and place the next clockwise wedge on top the assembly where it goes (as shown). Sew the full length of this seam. Press the seam allowance toward the pinwheel being careful not to press the partially sewn seam.
Lay the assembled parts down where they go in the block. Fold the loose end of the first wedge sewn out of the way as shown. Place the remaining wedge in place and sew the full length of this seam.
Fold the first wedge sewn to the front of the block to expose the partially sewn seam. Sew the remainder of the seam. Press the seam toward the pinwheel fabric.