Knife Edge Finish is the method of finishing a hexagon edge when binding is not used.
First, press under the 1/4 inch seam allowance on hexagon edge before removing the foundation paper. Then after the quilting is completed, hand baste about 1/2 inch from pressed edge.
Second, working in about 2 foot sections, trim backing and batting 3/8 inch (a little more than 1/4 inch) from the pressed edge of the top. Then trim the batting very close to the pressed edge of the top.
Third, clip the backing to the batting edge at the inside “corners”. Tuck backing over batting under the pressed edge of the top. Pin or Wonder-clip in place. I use an applique stitch to secure edges. Wonder-clips are worth the investment for a project like this, as they keep your work flat and you can nudge them along as you stitch and keep the fabric secure.