Embroidery Bobbin Types
The dimensions of a bobbin indicate its “style.” Each style is represented by a letter. The letter indicates the bobbin’s height and width. When referring to a specific bobbin style, often the word “type” or “size” is used instead of “style.”
Each sewing or embroidery machine uses a specific style of bobbin. Occasionally, two bobbins will be very close in width (or diameter), and a spacer can be added to adjust the height of the shorter bobbin, allowing the shorter bobbin to be substituted for the taller bobbin. However, the best embroidery results are achieved by buying the appropriate size/type/style of bobbin required for the embroidery machine.
While there are over 30 different styles of bobbins (as well as several sub-styles), 3 bobbin sizes/styles are most commonly used in embroidery machines in the U.S.A. and Canada. These sizes are Style A (also called a class 15 or class 15A or SA 156), Style L, and Style M.
Which Type Bobbin Does Your Machine Use?
Style A bobbins (also called class 15 or SA156 bobbins) – The bobbin type used in most home sewing machines, in most combination sewing/embroidery machines, and in many home single needle embroidery machines. Style A is often referred to as class 15 bobbins, and they come in plastic and metal versions. Home embroidery single needle machines use plastic bobbins, which are also called SA156. Pay careful attention to the embroidery machine’s manual concerning whether or not metal bobbins can be used, as using metal bobbins in an embroidery machine that only uses plastic bobbins can create a groove on the inside of the bobbin case. Do not use Class 15J bobbins (made for specific models of Singer machines) unless your embroidery machine’s manual specifies that bobbin type, as Class 15J bobbins have a curved edge and do not perform well in other embroidery machines. Style A bobbins can only be used in machines that take Class 15 bobbins. Style A bobbins are about as big around as a nickel. Style A bobbins are very close in width/diameter to Style L, but Style A is taller/thicker than Style L bobbins.
Style L bobbins – Size L bobbin is a common bobbin size for most commercial (multi-needle) embroidery machines and for some home embroidery machines. Size L pre-wound bobbins (bobbins already filled with bobbin thread) can be purchased in two versions: 1) side-less cardboard centers (with or without one of the sides being magnetic) and 2) plastic. Style L bobbins are about as big around as a nickel. Style L bobbins are very close in width/diameter to Style A, but Style L is shorter in height/thickness than Style A bobbins. When paired with a spacer, Style L bobbins can be used in Class 15 embroidery machines that normally take Style A bobbins.
Style M bobbins – The least common size of the 3 sizes, this bobbin type is used in industrial machines with more than one head. Style M bobbins are about as big around as a quarter. Type M bobbins are the largest of the 3 styles, holding approximately twice the amount of bobbin thread as Style L bobbins.
Other Embroidery Bobbin Types
Two other styles of bobbins should also be mentioned – Style G and Style U. Style G is very close in size to Style L, while Style U is very close in size to Style M. The sizes are so similar that the size difference may not be noticeable unless using calipers to measure.
Summary
Home single needle embroidery machine most likely take Style A (class 15 or SA156) plastic bobbins.
Multi-needle home or multi-needle commercial embroidery machine most likely takes Style L bobbins. Commercial embroidery machines may use Style L metal bobbins or Style L pre-wound bobbins. Style L pre-wound bobbins may be plastic or have a cardboard core.
If Style L bobbins are purchased by mistake for a Class 15/Style A embroidery machine, then a bobbin spacer (usually found in the machine’s accessory bag) can be used under the bobbin to allow use of the shorter Style L bobbin.
Metal bobbins should not be used in a single needle home embroidery machine unless the manual states otherwise, as most single needle home machines use plastic bobbins.
More Articles
Having bobbin problems? Check out our articles on cleaning the bobbin casing and adjusting bobbin tension and on cleaning the bobbin sensor.