Mooshie, are you talking about wavy borders or wavy backing? There are at least 3 reasons the bottom border is wavy... 1. when we quilt on a frame, the fabric can get stretched. When you unpin, it looks wavy. Try spritzing it with water or Best Press and walking away for a bit. When its dry, if the stretching was the problem, it will tighten up...some. 2 the borders don't fit the quilt well. Do you measure before you cut? or do you just cut a long piece and then trim? Its important for the top/bottom and both sides to match each other (not the sides and top..the side to side to match...clear as mud? sorry!) If you search on the QB, you will find border tutorials. if not PM me and I will find some. and 3. as we quilt down a quilt, the quilting pulls the quilt top up, leaving you more fabric along the bottom. I used to think I was doing something wrong, but like needing extra backing, its the nature of the quilting-on-a frame beast. You might think of SID and basting the whole quilt before you actually quilt it. This way you can measure and baste as you go down the quilt. I hope this helps. I'm not a longarm expert by any means...School of hard knocks for me!

THis is exaqctly how I do it and it works very well. I just unpin it from the leader, then put pins in -close together-along the whole edge and baste the edge. Then I remove the pins. Now if the bottom border had some fullness in it, the fullnessh has been worked in by pinning close together and then basting it so your bottom edge stays the same width as the rest of the quilt. You are now ready to finish quilting the bottom part of the quilt and it all stays in place.

I am confused by why you unpin the bottom of your quilt. When I load my quilt I pin the backing to both the upper and lower leaders with the backing being several inches longer than the quilt top. Then I pin the bottom of my quilt to the lower leader, roll it up and float the top edge close to the upper leader. I pull the batting up between the backing and top. I baste the top edge of the top and batting to the backing and then proceed on to do the quilting. It is also good to baste the sides of the top as you move down the quilt. You always need to have extra backing in the length as the quilting uses up extra fabric.

OKAY, I just re-read the original post. It sounds like you pin the backing to the backing leader, and the top to the top leader. I did this exactly once, and now I just float my quilt top, that is, I pin the backing and just lay the batting and top on the backing.
Here's a you tube on floating a top:
http://www.youtube.com/watch?v=Fpjep8O4U4s

Not saying that this is the "right" way to do it, just a different technique.

I completely understand what you're saying, and have had the same issue, and I know it wasn't because the quilt was wonky or wavy to begin with. I *think* that the problem occurs because I wasn't careful enough to keep the sides of the quilt completely straight, so that they started to angle in by the time I was at the bottom. That meant the extra fabric at the bottom had to be eased in, and the bottom wasn't as wide as the top.

The other thing that might be happening is that the quilting stitches cause the quilt to contract somewhat, so it looks like there is more fabric at the bottom, whereas there really isn't - it just hasn't been quilted yet. To take care of that, I try to unpin the bottom part of the quilt top before I get too close to finishing, and then pin the sides of the top to the batting and backing. That seems to keep it where I want it to be so the bottom is square.

Now that's what I've done... probably not the right thing... I'd love to see a video of someone doing it. I don't remember ever seeing a video of someone finishing the very bottom of a quilt.

Thank you for the replies. I have not been floating my top. I have been pinning it to the leader for the top. It's just how I was taught. But I think I will try a few things that were suggested here and see what I like. The 2 I like best are to just do as I have been, with basting the bottom b-4 quilting the last bit, and floating the top with basting the sides as I go. I've tried it with and w/o basting the sides down as I go, and don't really have a strong preference one way or the other as I don't see that either one makes a big difference. But I have known others who really like one way or the other.

Good thing I have a bunch of things to quilt, it'll give me plenty of practice.

I will say, I don't love pinning, so perhaps floating the top will be something I like, as I will get to avoid 1/3 of the pinning.