[EricH]

Let's see if this makes it any clearer. Take a long piece of string (actually, surgical tubing might be better) and wrap it around your frame, pulling tight. From each corner formed in that string, measure 8". Mark the frame in that location. Can't mark the frame, because it isn't there? You'll need to put something there. By the way, that string is the frame perimeter.


Any side of the frame perimeter that is <16" between corners will need bumper along its entire length due to the required 8" of bumper from each corner.