Cat- on- amac gives a good hint....sew 45 degree line at corner...and I use 2 1/2" binding..maybe that extra makes a better miter? I still go the old fashioned way of machine sew on front....but I do snip off the corner stuff to eliminate some bulk..enough is created by the miter..then hand sew to back..use straight strips, not bias. On some tv show ..maybe F&P I did see someone ( male, I think) cut the inside fold (?) off that miter corner too...have to go and check my "saved" programs...he claimed that gave a smoother miter corner.