When I've had my bobbin in backwards, it's just jammed and broken the thread. No weird stitches. But that's just me.
I adjusted the needle tension when I made my slapstraps. Apparently the thickness of the material, the looseness of the weave, or the width of the stitch (or some combination of the three) requires a lower tension. I was getting a lot of tangling, but as soon as I lowered the tension the problem stopped.
I've never adjusted the bobbin tension. In fact, most of the DIY sewing sites I've looked at said not to - it's apparently not necessary for almost any application.
Bookmarks