Prism99

Measure your actual seam allowance before you mark the corner. In other words, use your actual seam allowance and not the seam allowance you think you are sewing. Stop just one small stitch short of the mark; *never* sew one short stitch past the mark. When you fold the corner, make sure to finger press the fold down very well so the folds are *exactly* on the cut edge and not just a tiny bit bigger or tiny bit smaller.

I have found that not ironing the fold into the binding (before applying the binding) helps a lot with the entire binding, including the corners. Not ironing allows the outer layer of binding fabric be just a little bit bigger than the inner layer of binding fabric when you turn the binding.

After sewing the binding to the first side of the quilt, it helps to take the quilt to the ironing board and iron the binding away from the body of the quilt. This makes turning easier. (Again, do *not* iron in the fold at the binding's edge.)

At this time, it also helps me to see if I can get a good miter on each corner. When I am satisfied with the fold, I iron that corner into place. It helps to add a dot of glue on the part of the miter that your sewing machine will reach first. You can either leave the flap free or add a dot of glue to hold your ironed miter in place. I often find it helps to nip off just the tip of the batting at the corner (not any of the binding fabric! If you do it wrong, you can cut a hole in your binding!).

One other thing I do which most quilters would probably not want to do is this. I use a permanent Sharpie to mark "virtual" cutting lines on the edge of my quilt and use that to line up the raw edges of my binding. In other words, I do not trim the quilt to size before adding binding. I mark the cutting lines, sew the binding on using the mark as my virtual cutting edge, then trim the quilt to match the binding. This does not really help with the corners, as far as I can tell, but it helps me control the edge of the quilt.