Use a ruler to check the size of your block, trimming as necessary. If you cut accurately, sew accurately and press carefully, you should not need to trim your blocks.
Repeat these steps to assemble all the pinwheel blocks in the row, placing the completed blocks back on your design wall as they’re sewn. Repeat for each row.
Once all the blocks are sewn, you can start assembling your quilt. When sewing the blocks into rows, make sure you pay attention to which direction the seams are being pressed. If the first row’s seams are pressed to the right, the second should be pressed to the left. This will allow the seams to nest as the rows are sewn together and will allow for accurate pinwheel centers.
Sew the rows together to complete the quilt top. Press the row seams open to reduce bulk.