Originally Posted by
Mrs. SewNSew
I thought I had it until I tried the zig-zag! Why can I get the tension working well but when I do a wide zig zag it pulls together in the middle or the stitches pull through to show on the other side.
A wide zig zag often requires both tensions to be lowered somewhat. Think of it this way - a wide zz is asking for a fairly generous helping of thread in the same time and space that a single straight stitch would normally be pretty frugal. If the Wide ZZ needs, let's say 3 times the thread, it can't be fighting terribly hard to get it or the stitch will be malformed. Tunneling is a sign of this - it simply can't pull enough thread to lay flat on the fabric. Solve tunneling with looser tensions - often both top and bottom - depending on the machine and thread. The other thing that helps a wide zig zag is stabilization - just like with a decorative stitch. Decorative stitches btw are a lot like embroidery - it's OK to have the threads lock on the back of the work - typically you'd match your threads and it wouldn't be seen anyway. This way less puckering happens and if you haven't matched your threads, the top thread is the only one that shows.
Read the stitches and see which thread is having the supply issue - stitches lock at the back - bobbin thread is too tight. Locking at the top - top tension too tight. Depending on what I'm doing, sometimes I do change the bobbin tension a couple of times in a project. It's "rare" to have to change bobbin tension according to the manuals but I think they're assuming a fairly narrow range of fabrics and threads - sort of like how "automatic" should work in most cases. It does too - but only for a fairly narrow range of circumstances.
Originally Posted by
zozee
Does it matter if I turn the tension dial a little at a time or a lot? Is there something I could do that would ruin my tension to the point of needing a professional servicing? What should I NOT fear about messing with tension?
Assuming that you're not way out in left field to begin with - a little at a time will tell you more. I think wide swings are more likely to bounce to back and forth between too tight and too loose. The exception (somewhat) here would be with some long arm machines that have tensioners that turn "forever". Depending on the tensioner, usually unless you start disassembling (and losing pieces), you can't harm one permanently. I don't really recommend flossing lately. You can shove things in further complicating the problem. Most tensioners - post 30s-ish anyway have numbers on them. If you record where you start, you should always be able to return things to where you started. Bobbin tension is the same -count the number of turns til the screw is tight, then loosen or tighten as needed. In fact, one of the best things you can do is experiment - run a test sew from maybe 2 - 9 whenever you change threads and see how the stitch changes.