Did your sewing machine come with two bobbin cases and you have no idea why? I've got you. Below is information to help you determine which bobbin case to use and when to use it.
Before we begin, I do want to mention that this information applies to Babylock and Brother bobbin cases.
Green Screw Bobbin Case
I am calling this bobbin case the "green screw" bobbin case, because, you guessed it, it literally has a green glob on the tension screw. This is the bobbin case that comes with your machine. The thing to note about this particular bobbin case is you CANNOT adjust the tension. There is Loctite on the threads of the screw to ensure that the tension will not change. The tension comes preset from the factory to work with a 60 wt thread. By using Loctite, the manufacturer can say with confidence that the tension is accurate for that 60 wt thread. This bobbin case can be used for both sewing and embroidery - as long as you are using the 60 wt thread.
Purple Dot Bobbin Case
If you are wanting to use a different weight of thread, that is where the "purple dot" bobbin case comes in. The reason that I am calling it the purple dot bobbin case is, normally, there is a purple dot in the center of the bobbin case. Just note that there isn't always a purple dot.
It may be a different color, or, there may not be a dot at all. Just know that if there is NO green on the tension screw, then that is the indication that you are holding your alternate bobbin case.
This particular bobbin case does NOT have Loctite on the tension screw. That means that you can adjust the tension as needed, depending on the type of thread that you are using. This bobbin case can also be used for both sewing and embroidery! I am making sure to mention that because it is often believed that the alternate bobbin case is only for embroidery, but it's not! How cool is that?
Adjusting The Tension
If you are using a heavier thread, you would need to loosen your tension. If you are using a thinner thread, you would need to tighten your thread. A little phrase my technician taught me is, "Right to Tight and Left to Loose!" or you can use the good ol' standby, "Lefty Loosey, Righty Tighty!" When adjusting the tension screw, you want to think of the screw as the face of a clock. Adjust in 15-minute increments. After making one 15 minute adjustment, try the bobbin case and see if it is working well. If not, make another 15-minute adjustment and try again. Continue to do this until your tension is correct.
Thread Weight
If you are unfamiliar with thread weights, the lower the number, the heavier the thread. For example, a 30 wt thread is heavier than your 60 wt thread. A 90 wt thread is thinner than the 60 wt.
Conclusion
I hope that this has helped you determine why you have two bobbin cases and it also helps you know which bobbin case to use and when to use it. Until next time, Happy Sewing, Everybody!
