Tajima TMAR-KC Thread Breakage Troubleshooting Guide

1. Incorrect Thread Tension (Upper or Bobbin) high likelihood

How to tell

Perform a tension test by embroidering a simple satin stitch on scrap fabric. The bobbin thread should show approximately 1/3 on the underside of the top stitch. If the top thread breaks, tension is likely too tight or the bobbin tension is too loose. If the bobbin thread breaks, the bobbin tension is too tight or the upper tension is too loose. Observe the thread path for snagging or excessive slack.

Fix

1. Adjust the upper thread tension dial. Turn clockwise to increase tension, counter-clockwise to decrease. Make small adjustments (e.g., 1/4 turn) and re-test.
2. For bobbin tension, remove the bobbin case. If it's a drop-in style, hold the thread and let the case hang; it should slowly drop a few inches. If it drops quickly, it's too loose. If it doesn't drop, it's too tight. Adjust the small screw on the bobbin case (usually 1/8 turn increments) and re-test. Refer to your TMAR-KC manual for specific bobbin tension settings.
3. Ensure upper and bobbin tensions are balanced to prevent either thread from breaking or poor stitch quality.

Tension discs can wear over time, affecting consistency. Bobbin cases can also wear or become damaged.

Parts involved: Thread path & tension → Rotary hooks & bobbin cases →

2. Improper Thread Path high likelihood

How to tell

Visually inspect the entire thread path from the thread cone/spool to the needle. Look for missed thread guides, thread caught behind tension discs, or thread wrapped around the take-up lever shaft. Ensure the thread passes freely through all guides and the take-up lever eye.

Fix

1. Completely unthread the machine.
2. Re-thread the machine carefully, following the exact path shown in your Tajima TMAR-KC operator's manual. Pay close attention to all thread guides, pre-tensioners, main tension discs, and the take-up lever.
3. Ensure the thread is seated correctly between the tension discs and not just resting on top.

Parts involved: Thread path & tension → Head & mechanical parts →

3. Worn, Bent, or Incorrect Needle high likelihood

How to tell

Visually inspect the needle. A bent needle will be visibly distorted. A dull needle might have a flattened or blunted tip, which can be felt by gently running a fingernail down the point. A burr can be felt as a rough spot. Check the needle type and size against the fabric and thread being used; using a needle too small for the thread or too large for the fabric can cause issues.

Fix

1. Replace the needle immediately if it is bent, dull, or has burrs. Always use the correct needle type (e.g., DBxK5 for embroidery) and size (e.g., 75/11 for general embroidery, 90/14 for thicker threads/fabrics) for your application. Refer to your TMAR-KC manual and thread manufacturer recommendations.
2. Ensure the needle is inserted correctly, fully seated into the needle bar, and with the scarf (long groove) facing the rotary hook.

Parts involved: Needles & needle bars →

4. Lint or Debris Build-Up high likelihood

How to tell

Visually inspect the thread path, tension discs, take-up lever, needle bar area, and especially the rotary hook and bobbin case area. Lint and thread fragments will be visible, potentially clogging guides or interfering with moving parts. Excessive lint around the tension discs can prevent them from gripping the thread properly.

Fix

1. Power off the machine.
2. Use a soft brush or compressed air (with caution, directing debris away from sensitive electronics) to clean lint and debris from the tension discs, thread guides, take-up lever, and needle bar area.
3. Remove the needle plate and bobbin case. Thoroughly clean the rotary hook area, removing all lint and thread bits. Apply a drop of machine oil to the rotary hook race as per your TMAR-KC manual after cleaning.
4. Clean the bobbin case itself, ensuring no lint is trapped under the tension spring.

Parts involved: Lubrication & maintenance → Rotary hooks & bobbin cases → Thread path & tension →

5. Poor Quality or Old Thread medium likelihood

How to tell

Inspect the thread spool for visible damage, fraying, knots, or tangles. Old thread can become brittle; test by pulling a length of thread firmly – if it breaks easily, it's likely compromised. Inconsistent thread thickness can also indicate poor quality.

Fix

1. Always use high-quality embroidery thread from reputable manufacturers. Polyester or rayon threads are generally durable.
2. Replace any thread spools that show signs of damage, fraying, or excessive brittleness.
3. Store thread in a cool, dry place away from direct sunlight to prevent degradation.

Parts involved: Threads & supplies →

6. Incompatible Bobbin Thread medium likelihood

How to tell

Check the bobbin thread type and weight. Using a bobbin thread that is too thick, too thin, or of poor quality compared to the top thread can cause tension imbalances and breakage. Visible shredding of the bobbin thread can also indicate an issue.

Fix

1. Use a high-quality bobbin thread specifically designed for embroidery machines, typically a fine-weight polyester or spun polyester.
2. Ensure the bobbin thread matches the quality and type of the top thread for optimal performance.
3. Check bobbin tension as described in 'Incorrect Thread Tension' above.

Parts involved: Threads & supplies → Rotary hooks & bobbin cases →

7. High Machine Speed medium likelihood

How to tell

Thread breakage occurs more frequently at higher machine speeds, especially with dense designs, metallic threads, or on challenging fabrics. The machine may sound strained or vibrate excessively.

Fix

1. Reduce the embroidery speed, particularly for intricate designs, dense stitch counts, or when using specialty threads like metallic.
2. Experiment with different speed settings on a sample to find the optimal balance between production speed and thread integrity for your specific design and materials.

8. Incorrect Stabilizer or Improper Hooping medium likelihood

How to tell

Fabric puckering, shifting, or stretching during embroidery indicates stabilizer or hooping issues. This puts undue stress on the thread, leading to breakage. The fabric may not feel taut and smooth in the hoop.

Fix

1. Select the correct stabilizer type (cut-away, tear-away, wash-away) and weight for your fabric and design density. Refer to stabilizer manufacturer guidelines.
2. Hoop the fabric and stabilizer securely, ensuring the fabric is taut but not overstretched. Avoid wrinkles or loose areas.
3. For larger designs, periodically check that the fabric remains secure in the hoop.

Parts involved: Hoops & frames → Threads & supplies →

9. Tension Disc Wear or Misalignment medium likelihood

How to tell

Inconsistent thread tension despite adjustments, or visible grooves/damage on the tension discs. Thread may snag or shred as it passes through. Discs may not open and close smoothly when the presser foot is raised/lowered.

Fix

1. Power off the machine.
2. Inspect the tension discs for visible wear, nicks, or grooves. Clean any lint or debris trapped between the discs.
3. Ensure the tension discs are aligned properly and open/close freely when the presser foot is lifted and lowered. If discs are worn or damaged, they will need replacement.
4. If the issue persists after cleaning and inspection, the tension assembly may require professional adjustment or replacement.

Parts involved: Thread path & tension → Screws, springs & small parts →

10. Backlash in Bobbin Case medium likelihood

How to tell

The bobbin thread may unwind erratically, causing tension spikes and breakage. This is often more noticeable during rapid changes in sewing direction or speed. The bobbin may spin too freely or 'jump' in the case.

Fix

1. Inspect the bobbin case for wear or damage. Replace if necessary.
2. Consider installing an anti-backlash spring or a bobbin tension spring if your TMAR-KC model supports it and one is not already present. This helps maintain consistent tension as the bobbin unwinds.
3. Ensure the bobbin is wound evenly and not overfilled.

Parts involved: Rotary hooks & bobbin cases → Screws, springs & small parts →

11. Automatic Thread Changer Malfunction low likelihood

How to tell

Thread breaks specifically occur during color changes. The thread may snag, get caught, or not feed smoothly during the change sequence. Error codes related to thread change may appear on the control panel.

Fix

1. Power off the machine.
2. Inspect the thread change mechanism for any obstructions, bent components, or excessive lint buildup. Clean thoroughly.
3. Lubricate moving parts of the thread change mechanism as specified in your TMAR-KC maintenance manual.
4. If the issue persists, the mechanism may require adjustment or repair by a qualified technician.

Parts involved: Head & mechanical parts → Lubrication & maintenance → Sensors & switches →