This is about loading a quilt on a longarm quilting machine. If a quilt top is floated, it is basted at the top of the quilt and the bottom is flapping loose. That is, the quilt top is not attached to a zipper, roller or the backing until the quilt has been quilted and advanced to the bottom. Here is picture of a floated quilt.
Good practices:If you are going to sew, use your clamps. Clamps are attached to the backing only. The backing should not pull severely when clamped.
Terminology: ( you said you only have 3 rollers so you do not have a leveling roller)
Take-Up roller is at the back of the machine. It is the one "inside" the throat of the machine. Your quilt backing
will be zipped onto this roller. Your entire quilt will be 'taken up' on this roller
Belly roller is the one that touches your belly from the front of the machine. The bottom of your quilt backing will be rolled onto this roller.
The middle roller will hold the zippered bottom of the quilt top unless you float your quilt.
Full float means no zippers are used on the quilt top.
Zippers.... you will love them once you get the procedure down.
I float my quilt top so I don't use the zipper marked "quiltop bottom left". Before I began floating my quilts, I would baste (or pin) the bottom of the quilt top to the third zipper half also using my Domestic Sewing Machin (DSM).
Then I carry the pieces to my longarm.
-Zip the backing onto the take-up and belly rollers (top and bottom)
-Roll the backing onto the belly roller smoothing out puckers and wrinkles. Leave some slack in backing. The back-side of the backing should be face up.
- Zip the bottom of the quilt top onto the middle roller. Roll it completely onto the roller to keep it out of the way for now. (Skip this step for a full float).
-Place the batting on top of the quilt backing as close to the top of the backing as you can get it. You may want to pin it every 6". You will be basting this batting on so do not pin close to the top. With the top of the batting pinned to the top of the of the backing, smooth the batting along the width of the quilt and finesse the batting between the middle roller and the belly roller. Smooth it gently. The batting (and quilt top if floated) drapes over the belly roller and falls to the floor (depending on length; it is loose).
Tighten the belly roller carefully smoothing the batting on top too and set the brake (right front) on the belly roller. Do not make this tight or you will break thread when you quilt. You're not supposed to be able to bounce a quarter off the quilt
-Slowly baste the batting to the backing. Remove the pins from the batting/backing. Release the brake.
- Lay the quilt top (pretty side up) (unroll from the middle roller if you used zipper) carefully onto the already basted top edge of the backing/batting. Pin the quilt top about every 6" like you did the batting. Tighten the belly roller again smoothing the 3 layers and set the brake. Now baste the quilt top onto the backing/batting at the top near the take-up roller. Remove the pins.
The reason I float my quilts is I was finding bunny ears or stretched corners on the bottom of my quilts when I used the zippers on the bottom of the quilt top. The quilting process shrinks or pulls in the quilt as you quilt it. Then when you get to the bottom and the bottom of the quilt top is nailed to the zipper, there can be no pulling in there so it does not seem to match the rest of the quilt. It's really just matter of preference. I'm sure there is a way to use the zipper without the bunny ears, I just don't know what it is.
You are now ready to start quilting. By the way, don't forget to have fun.