Superior Education

Bobbin FAQs

  • Bobbin Thread
  • Prewound Bobbins
  • Bobbin Tension

Frequently Asked Questions about Bobbins

Q. Why should I use prewound bobbins when I can wind my own?
A. Good prewound bobbins are wound by high-tech machines which provide a smooth, uniform wind. The result is much more thread on the bobbin than a self-wound bobbin. Whether you're in the middle of an embroidery design or a quilting or sewing project, having to stop to change the bobbin is always an inconvenience. Prewound bobbins are game changers for dedicated sewists and quilters. The convenience of popping in a new bobbin without spending time to wind it is worth every penny.

Q. What does Class 15, L-style and M-style mean?
A. These are the three most common sizes of prewound bobbins. Some longarm machines (A-1, Gammill, and Handi Quilter) take the M-style bobbin, which is larger in diameter than both L-style and Class bobbins. L-style bobbins and Class 15 bobbins are nearly identical in diameter (Class 15 bobbins are about 0.5 millimeters larger in diameter). L-style bobbins used to be the most popular bobbin style but with the abundance of rotary bobbin mechanisms and drop in bobbins, the Class 15 bobbin style is now the most popular bobbin style for home sewing machines.

Q. Why are there three popular sizes of bobbins plus many unique bobbin sizes for sewing machines? Why isn't there a single, universal bobbin style?
A. Machine manufacturers make what they believe is the best bobbin for their respective machines. Some are made to fit only their machine and are not interchangeable with other machines, while others use a common bobbin style which is interchangeable with other machines. If a bobbin style is exclusive to a specific machine (think of the new Bernina 7 and 8 series, Pfaff Creative series, and several Singer machines), generic bobbins generally do not exist. We don't recommend choosing a machine based solely on the bobbin style. Machines should be chosen on what is most important to you, whether it's technology, number of stitches or features, or footprint. However, if your sewing machine or longarm machine uses one of the three popular bobbin styles, you have an added bonus of being able to use prewound bobbins.


MonoPoly prewound bobbins
MonoPoly prewound bobbins
Super Bobs Cotton prewound bobbins
Super Bobs Cotton prewound bobbins

Q. My dealer told me not to use prewound bobbins. I've even heard they will void my warranty.
A. This is 100% untrue. It's a myth. Today, almost all major machine companies sell prewound bobbins.

Q. Is there a difference between plastic-sided and cardboard-sided prewound bobbins?
A. Either type is fine. Plastic bobbins are reusable; cardboard bobbins are disposable. Because the plastic-sided bobbins are so smooth, they may continue to spin even after your machine stops and cause backlash. There is talk of some people experiencing backlash with plastic-sided bobbins and complaints fro others that cardboard-sided bobbins don't work with bobbin sensors. Our recommendation is to try them both. Find what works well for you and your machine.

Q. Is there a top side and bottom side to a bobbin?
A. Yes, there is a top side to a bobbin depending on your machine. If your machine specifies that the thread needs to unwind with the bobbin rotating in a clockwise direction, hold a bobbin flat in your left hand and pull the end of the thread with your right hand, unwinding the bobbin. As you unwind the bobbin, the bobbin should rotate in a clockwise direction. If the bobbin is rotating counter-clockwise, turn it over and the direction will reverse. By properly placing the bobbin in the bobbin case, the bobbin system can work as designed. If you use machine-branded bobbins, the logo mark on the bobbin is usually the top side. In summary, both sides of the bobbin are equal, but thread is usually meant to unwind in one direction. Watch our video on how a bobbin works.

Q. Should I use a polyester thread or a cotton thread in the bobbin?
A. It's a matter of personal preference. Polyester threads usually have very little or no lint. Depending on the quality of the cotton thread, the thread may create very little lint or an abundance of lint. When piecing, we recommend cotton thread due to its high heat tolerance and how it tends to grab the fabric to keep a tight stitch. Our Super Bobs Cotton prewound bobbins are wound with MasterPiece Egyptian-grown extra-long staple cotton thread.

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