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Bobbin Tensions and Bobbin Manufacturing Defects

Troubleshooting the Bobbin

To determine if your current bobbin is causing any problems follow the steps below. Two issues that can be caused by problems with the bobbin are Missed Stitches and Bobbin Showing on Top. Examples of both these issues are at the bottom of this article.

 

Baseline

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1) Bobbin Case   2) Plastic Sided Bobbin  3) Cardboard Sided Bobbin

 

  1. Use a Backup Bobbin Case (preferably new).
  2. Use an unused Bobbin.
  3. Make sure you are doing the Rotary Hook Maintenance when prompted.
  4. Make sure you are using the Recommended Bobbin Case.
  5. While looking at the front of the case, if you pull on the thread, the bobbin should be spinning counter clock-wise.
  6. Test the Bobbin Tension without the thread in the Pigtail and put it into the Pigtail before putting it back in the machine.
  7. Test the Bobbin Tension every time you replace the bobbin.
  8. If you are getting inconsistent bobbin tensions, try cleaning the bobbin case.

 

Bobbin Tension Gauge 

To accurately set the tension of your bobbin cases, it is recommend that you obtain and use the Melco Bobbin Case Tension Gauge P/N 34746.

 

1) Make sure the thread is seated in the rollers, not under them.

2) Smoothly pull the thread at approximately an inch per second, do not pull the thread too quickly.

3) The tension should be between 180 and 220 for an EMT16Plus, EMT16 or Bravo2.

4) The tension should be between 150 and 190 for an EMT16X  (Needle Plate Trimmer) 

5) The tension should not fluctuate out of spec.

Here are the instructions for using the Bobbin Tension Gauge.

 

Wrist Flick 

Hold the thread like a yo-yo and gently flick your wrist.

  • The bobbin should drop  ½ inch for an EMT16Plus, EMT16 or Bravo2.
  • The bobbin should drop 1 ½ inches for an XT, XTS, Bravo1 or EMT16X (Needle Plate Trimmer)

 

Styles 

There is no recommended style of bobbin for Melco machines, but different bobbin types might run into unique issues. If you have consistent issues after replacing bobbins, you might want to try a different style. Some styles are Plastic Sided, Cardboard Sided, and Magnetic.

 

For more information we have a video about Bobbin Tension Troubles & Solutions.

 

Recognizing Issues 

Missed Stitches:

If you see gaps where the bobbin is not tied into the top thread this is known as a Missed Stich. If you are getting missed stiches at the start of the sew after a trim, that is known as a Mis-start. Both problems are similar and have many shared steps to resolve the issue.

 

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The top column shows correct bobbin tension with red top thread.

The bottom column shows bobbin tension set too tight with gold top thread. You will see Missed Stitches and a Birds Nest beginning to form.

 

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The top column shows correct bobbin tension for an EMT16Plus and EMT16.

The bottom column shows the ⅓-⅓-⅓ rule, where you’d want ⅓ the thickness of the column to be bobbin. This information doesn’t apply to newer machines, it is more important to check for consistency. You should see bobbin tied to each stitch in the column without gaps.

 

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This is a picture showing the difference between correct and incorrect bobbin tension on a Fill Stitch.

 

Bobbin Showing on Top:

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This issue is usually caused from Bobbin Tension being set too loose, Acti-feed being too low, or a combination of the two.

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