Do you mean you have a lump where all the triangle tips meet? It is the same as 8 point star centers, you stop right at the 1/4 inch mark at the tip and you do not sew off the edge. This allows you to swirl the seam allowances on the back to get a flatter look. As for matching in the center, try matching them with a pin or a drop of Elmer's washable glue before sewing them.