Do you cut from selvidge to selvidge or the length of fabric? To prevent wavy borders.

I'm not sure it matters as far as wavy or not. If I have a long enough piece and I don't want to piece a border, then I do length of fabric. Otherwise, I do selvedge to selvedge.

I usually cut from selvage to selvage. Sometimes I will cut lengthwise, but I like to save fabrics. It depends on the quilt. I'm not sure which is better for the waves.

You must measure thru the center of the quilt top to bottom and cut the two side borders exactly then sew them on making sure they fit top, middle and bottom. Measure again across quilt including the borders you just sewed on, cut two borders, sew on top and bottom. This insures you will not have wavy borders. Wavy borders come from stretching fabric or not having the same tension on the top fabric as you have on the bottom. You should be able to gently lay the border on the bottom fabric smooth it and sew it so it fits evenly end to end. Pin it the first few times till you get the feel of it. Good luck.

Ditto!

Try starching your fabric, it will also help to eliminate the waves :wink: :D:D:D

I go selvage to selvage. It works for me. But do whatever works for you. No quilt police here.

As mentioned, the waviness comes from having a wrong measurement for the border piece.
Do the measure-across-the-middle lengthwise and widthwise, then cut both sides the same and both ends the same.
Find the middle of the side, and the middle of the end.
Pin the appropriate piece in the center, and then pin evenly out to each end of the side and end pieces.
No waviness.
.

You length wise cuts will stretch less than the width wise. I only do width wise if I don't have enough to do length.

However, with the price of fabric now a days width wise takes less! Just make sure and starch and handle carefully. Just my thoughts.