I have had the problem and what I found was my boarders were not square at the corners. Check to make sure they are square. I have started doing this every time and I have had not ruffling since then.

I do longarming and teach soldier quilt volunteers. This is the way I teach it, and the method that works best for me. It always produces perfect borders.

Measure lengthwise center, and both sides of quilt. Add together, then divide by 3, to get average border length (this is important). Cut each side border this length. Lay border on top of quilt, smooth gently, and see which piece is larger, quilt or border? Then pin border on quilt, ends first, then center, then remaining. Now to sew, put larger piece on the bottom of machine, by the feed-dogs. (They will ease in the excess fabric very nicely.) Then sew, making sure you don't pull or stretch anything...let the machine do the work. Repeat for top and bottom borders, including the side borders when you measure.

If mitering the corners, use the measurements as the inside border measurements.

Hope this helps :)

I agree. If your quilt doesn't lay flat before adding borders, it won't lay flat afterward no matter what measurement you take. So you need to figure out why, and fix it before you move on! I always lay the quilt flat, pin border on, leaving an inch or two at the top and bottom. Sew the border on, and then press the seam toward the border.Trim the border even with the top and bottom of the quilt, using the rotary ruler and cutter to be sure you are trimming it square. This works for me. I find that when your border measures less than the edge (if the center measures less than the edge) you will have one of two results - the edge looks 'gathered' into the border or the border is going to be stretched, and the result looks wavy.

If not put together in rows, how is the quilt put together.

Put the blocks together in pairs. Then put the pairs together into giant four patches. Then put the giant four patches together into pairs continuing until you have the quilt in four quarters. Sew the top and bottom quarters together and then the top and bottom halves together. You end up with only one long seam. Since you're putting the blocks into four patches you can make the block intersections match perfectly. That's where perfect matches matters the most. By the time you get to the end of a long seam any imperfections are multiplied. Plus when you add a whole row at a time if it's just a hair off that will be mulitiplied by the time you get to the last row and your quilt will tend towards trapazoid instead of square.

The biggest plus of all is you only have the whole quilt on the machine once.

I never measure....well, I do measure so I know I have enough border, but I don't cut it to "fit" before I sew it on! Just make sure you have enough border, sew with the quilt on the bottom and sew from top to bottom. I never have wavy borders. Oh, I also never pin...I hate pins. I also NEVER stretch the border. I just lay it on and sew away.

Could be you tensions (bottom & top) aren't even on your machine. Check your manual to remedy this problem. You may want to use a rolling foot, too. Ruffling of the border is probably a problem with one layer (border or pieced top) getting stretched more than the other.

Another hint: spray the edges of your pieced top and iron them flat (again) before applying the spray starched and ironed border.

When I sew the borders on I go to a slightly larger stitch than for piecing. Because you are sewing long seams sometimes the machine stitching tightens in places because of the way you guide the fabric thru or start & stopping, so when I loosen it by 3 stitches it takes care of that happening. I try to sew without stopping and simply let the machine pull the fabric thru. I have never had a wavy border

I measure down the center and pin the border (cut to that dimension) first on each end, then in the middle, then in half again, then in half again......If there is any discrepancy between the border and the outer side of the top, the difference will be absorbed or adjusted for evenly. If I don't pin, it has a tendency to get wonky. Once the sides are on, I press the seam and repeat the step for the other side.

pin centers, pin ends, and pin inbetween.