A professional longarm machine quilter for hire and some of the work I've done.
I had a question sent to me about the backing seams and I thought it should be answered in a post. Just in case there are others thinking the same question. Sorry Dee, I didn’t mean to take so long in answering.
Comment: if you need a backing 79×100, and your fabric is 42×216 (6 yards) – you would cut off the selvages; then cut (ok to tear?) the 6 yards into half. Resulting in 2 pieces 42×108. Cut/tear one of the 42×108 into 2 pieces and sew to either side of the other piece 42×103; resulting in your backing of 84×108.
If I load my backing so the seams are parallel to the poles, I would have to load my quilt top sideways? I’m not sure if I am doing this correctly.
When/how would you be able to run the seams parallel?
Tearing is ok if your fabric tears easily. I personally prefer cutting. Yes, you would be loading your quilt sideways so the three seams run the same direction as the bar. Each seam will lay on the bar one time instead of many times. The reason for loading a backing sideways is to prevent bulk in a single spot. With a small quilt you may not see it as a big deal because the bulk will be small. But, what if the backing is the maximum size your machine can handle and has multiple seams? You could potentially have a backing that looks very friendly (waves a lot) on the bar. Yes, you could quilt it but the chances of having tucks are increased with each seam.
If you are going to do a pantograph design on a quilt loaded sideways the panto will finish going top to bottom of the quilt instead of side to side so choose one that will be ok if seen sideways. I always thought pantos should go top to bottom anyway. Maybe because of striped wallpaper. Pantos remind me of it. Have you ever seen true striped wall paper going around the room? I haven’t. I’ve only seen it going floor to ceiling.
Do not tighten the tension between the bars too tight when a backing is loaded sideways. The stretch of fabric is selvage to selvage so loading a backing sideways means there will be more stretch. You need to keep it more loose than normal.
I try to load all the quilts sideways on my machine. Even those without seam issues. It shortens the time needed to quilt it and it has less bulk when rolled up completely on the take up bar. Of course I can’t do this every time but I do as many as possible this way. I mostly do freehand designs so the direction of the top isn’t a big concern like it would be for pantos. Over the years, with lots of practice, I’ve learned to draw designs left, right, up, down, and diagonal. This is very helpful when there will be a border design going around the outside of the quilt top. I do not have to remove and turn a quilt to do the borders.