No, this post isn't going to be about heavy metal bands too - I just couldn't resist.
But, really, I'll stop.
What I wanted to talk about was twisted seams. The real solution, to this as well as almost anything quilting, is to slow down and pay attention. I repeat that for me rather than you. For as much as I claim to love quilting, I seem to want to rush thru each step. Maybe it's the full-time job or the 4-year-old clamoring for my attention. I know it's not the housework.
This is what a twisted seam looks like:
As if you'd be reading this if you didn't know. But the top of the seam is stitched in the opposite direction from the bottom.
With my machine, this typically happens in one of two ways. The most frequent is when the bottom seam catches on the bobbin cover plate like so:
If I make sure I'm not putting too much downward pressure on the fabric, I can feel it lift as the seam opens and it's as simple as lifting the fabric & allowing the seam to flatten again.
The other way it happens is if the top seam gets caught on the pressure foot:
When that happens, I can just lift the front of the pressure foot for a second & allow the seam to flatten before continuing to stitch.
That's all - just pay attention & try to fix it before it gets to the needle. If you don't, it's worth unpicking and re-doing that portion of the seam. A top that contains twisted seams is not going to lay flat and if you do straight-line echo quilting, like I mostly do, the pressure of it is going to cause your quilting line to wave.