Make sure you sew from the middle out on both sides. If pinned well, you should be able to ease in the extra. Good luck.

Yu are right on the money with using easing to fix borders. I can confirm the wavy borders after easing in too much. Do you have some hints to avoid this? Sure is frustrating. Glad you brought this up.
Susan

The first thing is to start with a quilt that is square. I generally have less than a quarter of an inch difference between left, center and right. To get my quilts that even I don't put them together in rows. I make four patches out of the blocks and then turn those into giant four patches and so on until I have the quilt in four quarters and sew the two top halves and the two bottom halves together and then I just have one long row to sew. I started putting my quilts together that way because I really hated sewing long row after long row.

Once I have a square top I cut and piece side borders long enough. I pin the border on starting at the center and I pin every six inches or so. I do not measure. Then I sew the border to the top with the top next to the feed dogs. The feed dogs will always ease that side slightly. After both sides are on I press them and trim the ends off using my biggest square ruler. Then I add the top borders using the same method.

Hi, I just had some problems with borders, and to make matters worse the perimeter of my my quilt was all on the bias. I did use a lot of starch and instead of measuring with a tape measure, which was really messing me up, I used toilet paper. No I cannot tell you the length or width in inches, but I marked and cut the toilet paper the same size as the middle measurement on my quilt. To me it was easier than using a tape measure. Peace and Joy this Christmas

Bonnie Hunter's Quiltville site has a real good explaination of doing borders to fit. Quiltville.com love her site