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Facts and Frequently Asked Questions about Prewound Bobbins. 

prewound 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.

Q:. What does L-style and M-style mean?
A: These are the two most common sizes of prewound bobbins. Some longarm machines (A-1, Gammill, Handi Quilter, Homesteader, some Noltings) use the M-style bobbin, which is the larger bobbin. Some longarm machines (most APQS and Noltings) use the L style bobbin. Approximately 50% of home machines use the L-style bobbin. 

Q. Why are there L-size, M-size, A-size, Class 15, and other brand-specific sizes? 
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 make a common bobbin type which is interchangeable with other machines. If a bobbin type is exclusive to a specific machine, generic bobbins generally do not exist. Don't choose a new machine based only on the bobbin type, but if your machine uses one of the more popular sizes, you have an added bonus of being able to use prewound bobbins.

Q. Why use a colored bobbin thread instead of a white or grey (a regular neutral color)?
A. A perfect stitch is sometimes hard to achieve and therefore the bobbin thread may show on top. A white or black bobbin thread is high contrast and therefore can be visible. By matching the color of the bobbin thread to the top thread, the bobbin thread will blend. Then, if the bobbin thread does show a little on top, it will not be visible. When we speak of 'neutral colors' it isn't limited to the standard grey, cream, and tan hues. You can have neutral colors across the color spectrum. 

Q: Should I tear off the cardboard sides?
A: If the bobbin is too snug to accommodate free rotation (within the bobbin case), take off the cardboard sides. This will not affect the function of the bobbin. If your machine has an automatic bobbin sensor, leaving on the cardboard sides will make the sensor think the bobbin is always full and will therefore not provide a low bobbin warning. The solution is to either tear off the cardboard sides and use the sensor or to leave the sides on and sew until the bobbin thread runs out.

Q: Is there a difference between plastic sided and cardboard sided 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. Some machines seem to work better with the cardboard-sided bobbins because the cardboard sides provide more friction and backlash is usually not a problem. If it is, the bobbin tension may need to be tightened.

Q. Is there a top side and bottom side to a bobbin? 
A. Yes, there is a top side. 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.

Q: Should I use a polyester or a cotton bobbin thread?
A: It's a matter of personal preference. Polyester has very little or no lint. Depending on the quality of of Cotton, the thread may create very little lint or an abundance of lint. When piecing, we recommend cotton thread due to its high heat tolerance. I will use MasterPiece cotton thread both on top and in the bobbin when piecing. 

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

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By: Bob Purcell