Why is my thread looping on the bottom?


Since I first started repairing machines two decades ago, not a single week has gone by where I have not received at least one call asking me about looping thread on the bottom of the fabric. Since December 6th (today is the 22nd) I have received over a dozen calls and I was only in the shop 10 days. This is what they are calling about.  Almost everyone with a sewing machine has seen this at some point. It makes no difference what machine you own, it can make this stitch 🙂 Small or Large loops on the bottom of the fabric. The story is either “it was fine and now it’s looping on the bottom”, or the more common “I loaned my machine to my _____ (fill in the blank, neighbor, mother, daughter, sister, friend, etc.) and now it’s broken. There are large loops on the bottom of the fabric”. The reality is that only about one in a thousand machines are actually broken, so hopefully this article will help you keep sewing when it happens at 7:00 p.m. on a Friday night of a long weekend.

Unfortunately, many will immediately start adjusting their bobbin case. While this usually won’t stop us from getting rid of the looping during a phone conversation, it can make getting back to a balanced quality stitch more difficult. When you see thread looping on the bottom of the fabric, it is telling you that you don’t have any top tension. Loss of top tension can be caused by the tension unit(s), check spring, take-up lever, top tension setting, and thread path.

Here are two machines that were recently in for service. The Pfaff has a rotary hook. The Bernina has an oscillating hook. The Pfaff is mechanical and the Bernina is computerized. Both machines are in great condition and tuned up with only minor adjustments. Most would not even know I had made the adjustments. But since it was the Holiday Season and many of you are trying to finish that last little project, I put green thread on the top and red thread in the bobbin so you could see how these machines are both capable of producing the stitch shown above.




Here is a sewing sample from the Bernina. The simple truth is that oscillating hooks can better hide some basic setting problems.

The image on the left (red thread) is the bottom stitching and the image on the right (green thread) is the top thread. Without changing thread or fabric, we go from a quality stitch to a mess by the way we thread the machine. I know that many of you have been threading your machine for years and can do it with your eyes closed. Which is often the problem. Threading the machine while visiting with someone, or while looking at other parts of your project. Although your hands went through the motions, the thread skipped a step for you (the pre-tension unit, the tension discs or tension unit, the check spring, the take-up lever). You just can’t trust thread to do what it’s suppose to do when you’re not watching it closely 🙂 There are also the times when pushing and pulling fabric creates a thread loop that let’s the thread escape from a place you had properly put it (this is commonly a result when “chaining” quilt pieces).

Over the years I have learned not to tell women on the phone that it’s a threading problem. Some assume I am questioning their sewing skill, machine knowledge or general intelligence. Not a good way to start a conversation if you are trying to help. So now I usually start with “it’s a tension issue, cut the thread at the spool and pull the thread out at the needle. This will help clear any lint or dust bunnies in the thread path (it is also because you should NEVER pull your thread backwards through your machine. Bad things can happen, and depending on your machine, some expensive bad things can happen). Now make sure your bobbin is inserted correctly and the bobbin case is inserted all the way”. We then go through the re-threading of the top and that is usually the end of our machine discussion, so we close with thank you’s and other pleasantries and chit chat.

About 15% of the time, that does not solve the problem and then we look at top tension settings, which are down in the 0-2 range. Adjust the top tension back to “normal” and the problem is solved. On the rare occasion (these are very rare) that the problem still exists I ask if they broke a needle (almost always yes) which can result in a burr on the hook which won’t let the thread escape to complete the stitch. If the answer is no, I will have them again cut and remove the thread and then (with the presser foot raised) have them put some canned air through the tension discs (more common with intermittent loops every so many stitches) to clear any lint or thread pieces. If there is still a problem, then this is when I listen sympathetically to their need to complete their project. If they are close to my shop, I will usually try to polish the burr while they wait.

As I said above, oscillating hooks are better at hiding adjustment problems. Here are the samples from the Pfaff with the rotary hook.

Again, the top thread is green and the bobbin thread is red. As you can see, it makes no difference if your machine is new or old, mechanical or computerized, oscillating hook or rotary hook (drop in bobbins are rotary hooks ((exceptions are so rare, I’ll pretend they don’t exist))). If your machine is not broken, it can create the thread looping under the fabric stitch with the right adjustments or top threading changes.

So when the looping starts… DON’T PANIC!!!  Take a breath, get another cup of coffee (or glass of wine) and re-thread the top end of your machine. Check your top tension settings. Then… keep on sewing.

May Your Thread Never Break



I will put this article on the tips and tricks page along with several other TNT (Thread, Needle, Tension) issues.