Stitch quality on a long arm quilting machine
What causes a long stitch on a longarm and how do I correct it?
I do not quilt on a long arm machine, so I don't have direct experience. That said, I suspect that just like on a domestic machine, that when all of a sudden you have a long stitch, that really what you're seeing is a skipped stitch.
How a stitch is formed on a sewing machine
The basic operation of the your machine is like a sewing machine. The thread flows through the machine and through the needle eye to finally form a loop behind the needle. The rotary hook snags that loop and twists the threads together into a stitch. On a domestic sewing machine, all this happens while the machine is moving at 14 stitches per second. Yes, you read that right...per second. I'm assuming that a long arm machine moves at least that fast.
If the loop doesn't form at the proper time
, there's no stitch formed. That's why they say the 'timing' is off.
See the makings of a stitch
There's a great video of the operation on my page How Sewing Machines Work
. Just scroll down that page a bit to watch it.
Now sometimes it's the actual timing of the parts coming together that is off. Then you need to get out your tool kit and your manual and make the necessary adjustments (or call your dealer if you are uncertain as to how to fix the timing).
Check your needle
But timing can also be off for other reasons, most often needle related. I've written about these problems on my page Solving Your Sewing Machine Problems: Skipped Stitches
One problem that often occurs is that the needle 'pulls' on the fabric as it passes through. This is called 'flagging'.
What it means for you is that the pull of the fabric doesn't allow that loop to form either at all or at the proper time, causing a skipped stitch. I would definitely replace your needle with a new one to ensure that the point isn't damaged. If that doesn't work, I would try the next size larger to see if that makes a difference. Both of these actions would minimize the chances that the needle is having a harder time piercing the fabric, causing drag and interfering with the stitch formation.
Readers, if you are a long arm quilter and can offer advice, we'd love to hear from you. Please use the 'comment' link below to share.
Jenny, I hope this has at least started you on the path for dealing with this problem. I wish I could have been of more help.