What’s the difference between bobbins?
If you are a little bit of a sleuth, you can find several different bobbin types on the market today. Some are pre-wound with cardboard sides. Other pre-wounds are on a plastic bobbin. Still others have no sides at all! Some without sides are common with embroidery machine users.
You can find “magnetic core” bobbins (Fil-Tec is one brand) that help reduce backlash or overspin with bobbins. The magnet grabs the bobbin case and puts the brakes on the bobbin, stopping it when you stop.
Your backlash spring inside the bobbin case serves the same purpose. Backlash springs do wear out. Check yours by inserting the bobbin into your case, and then pushing down on the bobbin. You should see a little bit of “bounce” in the bobbin from the backlash spring. If you don’t, then you can replace the spring, or pop it out and gently bend the two little “fingers” up a bit more so that they put more pressure on the bobbin.
Plastic bobbins are really “one use” only if they were pre-wound. The plastic is not as dense as normal machine bobbins, and it will warp or split under the pressure of most high-speed winders.
Aluminum bobbins most closely resemble the “weight” of pre-wound bobbins. They are popular since a quilter can wind her own bobbins without having to adjust the tension as much when switching between self-wound and pre-wound bobbins. Metal bobbins are heavier, and require less bobbin case tension. These were the first bobbins available and are still loved by many quilters. However, thanks to technology, you’ve got lots of choices, for convenience as well as cost!