BOBBINS
Spun polyester bobbins are used for embroidery and lightweight garment sewing. In most cases with heavier duty it does not matter if the bobbin thread is nylon or polyester. If an item is used outdoors, use polyester thread because it has better sunlight (UV) and mildew resistance.
Style A (Class 15) Bobbins are typically used with home, and small commercial machines for garments and embroidery. There are some industrial machines that also use this bobbin.
Diameter: 13/16" (0.815 In.), 2.070 cm
Height: 15/32" (0.465 In.), 1.181 cm
Style G Bobbins are typically used in small and mid-sized commercial sewing machines for sewing garments, fabrics, leather, and upholstery.
Diameter: 55/64" (0.861 In.), 2.19 cm
Height: 25/64" (0.39 In.), 0.99 cm
Style L Bobbins are the most common bobbins used in home sewing machines.
Diameter: 27/32" (0.837 In.), 2.13 cm
Height: 23/64" (0.359 In.), 0.91 cm
Style M bobbins are normally used with mid-sized and large commercial machines for heavy fabric, canvas, upholstery, and leather.
Diameter: 1-1/64" (1.02 In.), 2.60 cm
Height: 7/16" (0.435 In.), 1.10 cm
Bobbins are packaged in a box by the gross or half-gross. A full gross is 144 bobbins. A half-gross is 72 bobbins
The thickness of the thread used on the bobbin is called its thread size. Thread size designations for bobbins are the same as for top-stitch thread. As thread size increases, the thread's tensile strength increases and the number of yards thread on the bobbin decreases.
