Those quilts look gorgeous to me! One trick I learned for getting that "scant" 1/4" was to use a stack of maybe 8-10 small post-it notes, placed on the machine right where you lay your fabric. Set it up and check it to make sure it sews that scant 1/4", then just use that to line up all your fabric as you sew. Hope I explained it well enough that you "got it!"