Bobbin Sizes: Understanding the Sizes of Bobbins

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Whether you work with different sizes and types of sewing machines on a regular basis or you are simply buying extra bobbins for your home sewing machine, it is important to know about the different bobbin sizes. ZJ explains about several of the different bobbin sizes, what machines they work in and how using the wrong size can affect your stitch quality.

Understanding Bobbins Sizes

Similar to many sewing tools, bobbins come in many various sizes and styles. Some are labeled with letters, like an ‘M’ or ‘L’ bobbin, while other are numbers, like 15. Knowing what type and size of bobbin your machine takes is important. Not all bobbins are clearly labeled with their size or style, however your machine manual should tell you what bobbin size your machine takes.

ZJ shows several of the different sizes and explains what machines they are for. Larger bobbin sizes are typically for long arm quilting machines or some embroidery machines. These machines are stitching very fast, and if they used a small bobbin, you would constantly be changing one out.

Types of Bobbins

Bobbins not only come in different sizes, but also in metal as well as plastic, and empty as well as pre-wound. While machines can only use one bobbin size, whether it is plastic or metal does not typically matter, however consult your machine manual to be sure. When buying bobbins, you can either buy them empty and learn how to wind a bobbin or you can find them pre-wound.

ZJ explains that some machines have issues with pre-wound bobbins and you may find your stitch quality is not where you want it. Some pre wound bobbins also come with cardboard on both sides that may need to be removed. Whether you buy empty or pre-wound, it is important to buy the correct bobbin size.

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4 Responses to “Bobbin Sizes: Understanding the Sizes of Bobbins”
  1. Patricia Watt

    Are all size 15 bobbins interchangeable? Metal and plastic? 15J vs. plain 15? My machine manualdoes not have the bobbin size anywhere. I read every word. So I was watching two different instructional videos on that model, and one said 15J, and the other said 15. I called the company, and also got an ambiguous answer. The girl who answered the phone said 15J and then corrected herself to 15. 15j came with the machine. Now I’m really confused. I’ve measured everything I can measure, and I can’t see any difference between them.. are they interchangeable?

    • Customer Service

      Hello Patricia,

      Class 15 bobbins and size 15J bobbins are generally not always interchangeable as the 15J is slightly smaller. However, one of my personal machines uses class 15 bobbins and I accidentally purchased 15J bobbins for it. The only place this was an issue on my machine was on the bobbin winder- the class 15 bobbin wound just fine but the 15J just spun in place. The 15J that I purchased were pre-wound and using the bobbin straight from the package did not affect my sewing, however I just can’t rewind them.

      This being said- if 15J came with your machine that is the type you should use.

      Hope this helps!

      Ashley NSC Video Membership

  2. margotbeebe

    Ticket 21861 My plastic “j” bobbins keep breaking, and the thread is a tangled mess and I end up tossing the broken bobbin and its thread. I asked Singer if there was a metal J bobbin that I could use, but they said only the plastic is right for my machine. Any thoughts or comments?

    • Customer Service

      Dear Margot,

      Thank you for your patience. In response to your question-

      If that is what they say- I believe they would know best for their brand of machine. However you can get additional bobbins online that you could try in your machine. Also, check other issues- like ensuring that your machine is threaded correctly- as there could be an underlying issues.

      National Sewing Circle Video Membership


Tags: bobbins, Free Videos, sewing machine, thread, thread breakage, ZJ Humbach