How to read a stitch, top and underside
Okay. You've been sewing straight lines for a couple lessons now and I keep telling you the stitch is fine, or the stitch is telling you something. Today we're going to actually learn what it's telling you, instead of just trusting me on it.
Here's the thing. Every stitch has two sides, the top and the underside, and they're supposed to look the same. Not similar. The same. If you flip your fabric over and the bottom looks different from the top, that's not a style choice, that's your machine complaining about something specific. Once you know what each complaint looks like, you stop guessing and start fixing.
What a good stitch looks like
Grab a scrap, two layers, sew a line. Flip it over.
A good stitch has the thread meeting in the middle, right inside the fabric layers, where you can't actually see it happening. From the top you see even little dashes of the top thread. From the bottom you see even little dashes of the bobbin thread. Neither thread is showing loops on the wrong side. That's clean. That's the only word I've got for it, and it's the whole goal.
The two most common bad stitches
Loops on the top. If you're looking at the top of your fabric and you can see little loops or bumps of thread sitting on top of the stitch line, your top tension is too loose, or your bobbin tension is too tight relative to it. The top thread isn't getting pulled down far enough to meet the bobbin thread where it should.
Loops on the bottom. If you flip it over and the bobbin side is loopy or the top thread is getting pulled clean through to the underside, your top tension is too tight. It's yanking the top thread down too far, past the meeting point, and dragging it through to the back.
Say it back to yourself like this: loops on top, loosen the top or check the bobbin. Loops on the bottom, loosen the top tension dial. It's almost always the top tension dial, honestly. The bobbin's usually innocent.
Do this at home
- Cut four or five scraps of the same fabric, two layers each.
- Sew a line on each one.
- Flip every single one and actually look at the back before you decide anything's wrong.
- If it's bad, change one thing, tension dial up half a number or down half a number, and sew another scrap. One change at a time. I mean it. If you change the tension and the needle and the thread all at once you'll fix the stitch and never know why, and next time you're back to guessing.
Measure twice applies here too, it's just, check twice. Check the back before you commit to a real seam on a real garment.
The story that taught me this the hard way
My first month with my own machine, I fed a seam through and the whole thing jammed up underneath the plate. Thread everywhere, this actual bird's nest tangled around the bobbin case. I didn't call anybody, I just took the throat plate off, cleaned out the lint and thread scraps, pulled the feed dogs clear, and rethreaded the whole machine top to bottom like I was starting from nothing.
Ran a test stitch. Still a mess.
Turned out my thread had never actually seated down in the tension discs. It looked threaded, it just wasn't sitting where it needed to sit, so the machine had zero tension control on the top thread the entire time. Also, and this is the part that still makes me a little warm in the face, my presser foot was up the whole time I threaded it. The tension discs only grip the thread when the foot is down. Rookie thing. Completely rookie thing.
The reason I tell you this isn't to make you feel better about your own mistakes, though it should. It's that the bird's nest wasn't the machine being broken. It was the machine telling me, very loudly, that something upstream was wrong. Reading the stitch is just a quieter version of that same message. Loops instead of a full jam. Catch it at the scrap stage and you never get the jam at all.
Before next time
Sew five scraps, flip every one, and bring me the back sides you're not sure about. Don't fix them first. I want to see what confused you.