This tutorial is long over due. Thank you Daryl for the inspiration to get this done. I have a pattern #351 Tree Skirt which has a some what unconventional way of attaching the outer border. Here is a step by step on how to attach that border. Begin with following pattern directions to piece your center. OK, it isn't a Christmas tree skirt but hey I already made three of those.
The center will be an octagon when completed.
Cut your outer border strips and keep them handy, as you will add each one when you run out of previous strip. Outer border first strip-lay the strip RST and leave a long tail at the beginning (where stiletto is pointing). Begin sewing at the center of that block (where pin is in fabric). Sew until you reach the end of the block (or where it turns to the next block).
Stop sewing as you reach the end as shown below. Heat set your seam and press open.
Cut the access off the right hand side ONLY, straight up, use your ruler along the seam as your "straight" guide. cut even with the edge of the block.
Depending on the size of the tree skirt you are making, you may be able to use this access piece as your next strip of border. Lay the second outer border strip RST making sure that the top left hand corner overlaps the edge of first border piece (as shown below). Sew straight across till you reach the end of block (as before).
Remove the access triangle from strip #1. Use the edge of ruler and edge of fabric as your guide for cutting. Heat set seam and press open.
Using the 45 degree angle line of your ruler and the seam you just sewed, trim away access border strip #2. Repeat these steps for each of the sides of your tree skirt, until you come back to that long tail at the beginning.
A close up of the 45 degree angle nestled into the seam you will remove the part that still has salvages attached.
Back at the beginning, your skirt should look like this, with a seam half sewn.
Fold over piece number one RST pin in place and sew straight through till you reach the mid point and the stitches that started this whole thing off.
Stitch towards your first set of stitches. Back stitch to lock them down.
Complete with trimming steps as before, and your skirt is ready for sandwiching and quilting.
Now where did that black tinsel tree go? Cause its time to decorate for Halloween.