Originally Posted by
ClairVoyantQuilter
This happens because the longarmer didn’t cut the batting to the width of the backing.
As the quilt winds on the takeup bar, the outer edges begin to flop around because of the slack and a pucker can result.
This can happen whether the quilter is using a computerized system or freehanding.
this is exactly why this can happen. Other reasons would be an off square back (which Rhonda already said was not the case), a back that was pieced with grain going several different directions (a problem I ran into with a customer quilt and could not solve with the backing she gave me--so I knocked off 1/2 the price), and recently I had my own quilt with flannel backing and the quilt design was pulling the back first one way then the other and creating ripples--had to unstitch and starch/steam and make sure those side clamps were doing their job! Hope this helps you for figuring out in the future Rhonda--sounds like you did your part though.