I've loaded my quilt backing, and have it straight, rolled it a few times to make sure everything is straight, but even though I have rolled the backing a few times to get the fabric to behave, it still sags on the right hand side for the first 16" or so...have any advice or help what to do...will it be ok to just put the batting on and top and start to quilt it? my table and everything is level so it's not that...I know that I was told to roll the backing several times to get the fabric to behave, but my heavens how many times do you have to do this....

Is the backing square? If so do you have anything on the rack to give it side tension? You can use something as simple as one of those pincher type clothes hangers for pants and a bungee cord if your rack is not set up with side clamps.

I have side clamps...just thought it shouldn't sag even before I put the side clamps on..but will try that. I measured and remeasured the backing and it measure that it is square.

Ok so I put the side clamps on and it did pick up the sagging on the right side, not perfect but it should be ok (I hope so) fingers crossed

It does sound like it may not be square. You'd be surprised how much being even a little bit off will throw this off.

it doesn't sound square to me either - the fact that its one side makes me think it isn't square.

did you roll it on evenly? maybe you skewed it to one side cause the other side to have slack in it.

The other thing that can happen is a crease in your canvas leader. To check for a crease, you have to unroll the whole thing and then reroll.

In the event of no crease, your backing fabric is not squared.

how did you 'load' it? did you pin the backing to leaders? or baste it? it could be off because something there is out of line

I pinned the backing to the leader. but by putting the clamps on it did pick up the slack. So would it be ok to just go with that, or do you recommend taking it all off remeasuring the backing and start over? This is a quilt for a charity auction and not a customer.

if for charity just go for it-it does sound like backing is not square

No clue if this will help, but I have an out-of-square quilt in my hand quilting frame. I put a few pieces of batting in the quilt roll on the longer side of the misshapen quilt to take up the slack. I'm sure I've committed an unpardonable sin, but it made it easier to work with.