I was told in order to make sure a quilt is squared up I am to measure the top, middle, and bottom width divide by three and that will give you the length of the next strips to cut length wise. I am to do the similar for the length as well. Why do I really do this and what's the difference of just squaring up a squaring ruler? I'm confused.
The reason to use the average measurement is to aid in squaring up the top. Say the top is 36 1/2inches, the bottom is 36 inches and the middle is 36 1/4. Then added together you get 108.75 inches. Then divide by 3 to get 36.25 inches to cut for your top and bottom border strips. This means that the strip will be shorter than the top, so when you sew it on you will be easing in the extra 1/4 inch along the whole length of the top. The strip will be 1/4 inch longer than the bottom, so you will 'stretch' the bottom to fit the strip. Now you have exactly the same measurements on the top and bottom. Next you do the same for the sides. Now the top has been squared up. Remember to sew with the longer piece of fabric on the bottom so that the feed dogs can do the work for you. Personally, I still usually check with my 22 inch square ruler and sliver trim if I've managed to stretch the fabric. The main advantage of this method is that any differences can be eased in so that anyone looking at the quilt will never know it wasn't perfect. For me, this works best with a 4 or 6 inch border vs something narrow like a 2 or 2.5 inch border. Any 'wobbles' will be more noticeable when the strips are narrow. The most important thing to remember is that we are our own worst critics and the little things that we notice, won't be notice by someone else. :-)
Mineral Wells, West Virginia