When a long armer gets a quilt from a customer to be quilted, is the quilt sandwiched and pinned/basted? Is the backing larger than the filler and top? OR does the LA put it together?

The LA will put it together. Your backing should be min of 4" larger on each side (8" longer and wider) than your top.
The LA rolls the top onto one roll and the backing onto another. If you sandwich it before hand, it actually makes it harder for them.
I am not an LA, and you should check with yours to see how much extra they require.

The top is completed, should be squared and the backing should measure 6" larger (this is my preference, I can get away with less on the sides but need the full 6" on top and bottom to allow room to attach to my leaders) on all sides and also squared up. No sandwiching or basting as that is done when putting it on the rack.

You can discuss with your LAer if you want to supply batting or if they will. Some LAers will also square up your backing for you but it is up to you to ensure your top is square. By square I mean your top end measurement matches your bottom end measurement and your right side measurement is the same as your left side measurement.

You do not sandwich the top, batting, and backing. The top and bottom go onto the frame separately and the batting is loaded between them and then only the very top of the batting is basted to the backing. The three pieces are moved together each time the rods on the quilting frame are rotated.

Interesting - thank you!

do not sandwich your quilt - your LA'er will do it as she puts each part on a different roller. I am not a LA'er, I have a mid arm machine and only quilt for myself. But I cut my backings a minimum of 6 inches larger than my top and it works great

should go in 2 or 3 separate folded pieces- a neatly pressed top=
a neatly pressed backing
and a batt- unless the quilter provides the batt

the backing and batting should be larger than the top---i tell my customers at least 5" all the way around (meaning if your top measures 80"x90" the batting and backing needs to be AT LEAST 90"x 100"
i think some la'ers do not require that much- that is my (wish)
you top and backing should be squared (the backing should not have rough= scissor cut ends)
if the top has alot of seams along the edge it is also a good idea to do a stay stitch all the way around the top-
when the top is loaded on the frame it is held taut- and sometimes those edge seams come undone unless they have been stay=stitched....just a straight stitch about 1/4" in all the way around will keep everything together during the process.

I agree. Ask your LA'er how much extra fabric she wants around the backing.

Iron the top and the backing.

Remover any pet hair and stray threads.

Roll the batting. No folding creases if possible. I recently received a quilt to do and the backing was more poly and it was awful trying to get the creases out of the backing. Nothing I did helped much with the batting. I wonder how long she had had it tightly folded and where.

ali