Consew Sewing Machines: Bobbin Case Assembly, Disassembly, and Tension Testing

Resource Description

Contents

• The Elements of a Bobbin Case
• Bobbin Case Assembly & Disassembly
• Bobbin Thread Tension Testing & Adjustment
• Conclusion

The Elements of a Bobbin Case

A bobbin case is a part of the machine that holds the bobbin when you are sewing. Let’s consider the bobbin case parts. Look at the picture below:

There is a tension spring (A) and two screws. The larger screw (B) is used to adjust the bobbin tension. The smaller screw (C) holds the tension spring to the case. The small screw isn’t designed for the tension adjustment. Don’t turn it. Otherwise, you can lose this screw as it will come easily. The backlash spring (D) (also known as the bobbin brake spring or the anti-backlash spring) is designed to act as a brake. When the machine is stopped, the backlash spring stops the bobbin spin.

Bobbin Case Assembly & Disassembly

So you have a Consew sewing machine and need to disassemble, reassemble, test, and adjust the tension on an L-style bobbin case. The task is easy if you know how to do it. Follow the instructions below.

How to disassemble a bobbin case?

1. Remove the backlash (it is a spring that is used for a metal bobbin or a plastic-sided bobbin to prevent it from spinning too fast in the case and giving you a knot that you don’t need).

If you have sideless, cardboard-sided, or magnetic bobbins, you need to remove the backlash spring before using the bobbin with the case.

2. Remove the tension spring on the bobbin case.

The tension spring is attached by two screws. The smaller one holds the spring in place and the larger one is used to adjust tension. Now you need to remove both of them.

Here’s what you will have in the result:

How to assemble a bobbin case?

1. Put the tension spring in place. Start with the larger screw. Then goes the smaller one.

2. Put the backlash back in place. If you have a magnetic-sided bobbin, you can leave the backlash out. If you are using a metal or a plastic-sided bobbin, here’s how you can put the backlash back into your bobbin case. There are four points on the backlash (they serve as clips once you insert the backlash into the bobbin case).

There are also four points on the bobbin case (for those clips). Put the backlash into the bobbin case, and push it gently, making sure that those four clips of the backlash fall in the gaps corresponding with the bobbin case.

Once the backlash is in the correct place, you will notice that the sides of the backlash sit flush with the flat part of the bobbin case.

3. Thread the bobbin case.

Insert the bobbin.

Route the thread through the thin slot opening (A) and then under the tension spring (B).

Bobbin Thread Tension Testing & Adjustment

Now let’s test the bobbin thread tension. There are two methods.

Method 1

Take the bobbin and hold it like a yoyo. Then flick your hand down, the bobbin should go down (2-3 inches) and then stop. That’s the right tension.

If you flick the bobbin down and it doesn’t move, then the tension is too tight. If the bobbin goes all the way down and hits the table, the tension is too loose. To fix this situation, use the bigger screw of the two on the bobbin case to tighten or untighten the tension.

Tension adjustment

Turn the screw to the right if you need to tighten the tension, turn it to the left to loosen the tension.

Method 2

Use a bobbin case tension gauge.

Insert the whole case into the gauge on the spool, lining up the case latch with the notch at the top of the spool area. You will hear the click sound.

When the thread comes off the bottom of the case, thread it under the first spring, then up and over the second one.

Move the thread down and around the hook back at the bottom of the gauge. The gauge needle will move.

Pull the thread consistently directly to the left for about 1-2 inches. You’ll see the needle pull down and become steady.

The number where the needle stops indicates your bobbin case tension. For embroidery machines, for example, the bobbin case tension can be between approximately 200 - 250 (300) mN (depending on the application). In other cases, the range is between 180 (190) - 220 mN. But you need to adjust the tension specifically for your task.

Make adjustments if necessary. If you need to increase the tension, turn the screw to the right, to decrease - turn to the left.

When the tension is set, put the bobbin in the case back into the machine.

Conclusion

We hope that now you know the elements of your bobbin case, understand how to disassemble/reassemble it, and also test & adjust the tension on an L-style bobbin case.

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