Stop “Mystery” Thread Breaks on Melco Embroidery Machines: The Bobbin Flare Test + Towa Gauge Numbers That Actually Matter

If you run a commercial embroidery floor long enough, you learn a hard truth: not every “tension problem” is actually a tension problem. Sometimes, it is a $2 bobbin quietly turning your precision rotary hook into a brake pad.

This post rebuilds Mike Doe’s core lesson from Melco’s applications team into a shop-ready routine. We will transform technical theory into sensory skills you can repeat any time you see sudden thread breaks, fraying, or weird stitch behavior right after a trim—especially if you just changed bobbins.

Don’t Panic—Most “Melco Embroidery Machine” Tension Chaos Starts With One Cheap Part

When a machine that was sewing perfectly suddenly starts breaking thread or destroying garments, your brain naturally wants to blame the expensive parts: the needle bar, the timing, or the digital design. I get it—downtime is fearful.

But for operators of melco embroidery machines, the fastest “sanity check” is the bobbin itself—specifically, cardboard-sided L-style bobbins that are out of spec.

The issue is simple physics: some cardboard-sided bobbins flare outward like a subtle bell bottom. Inside the machine, that flare presses against the back metal wall of the rotary hook. This creates mechanical friction, which mimics high tension.

If you only take one thing from this guide, take this: before you touch a single screwdriver, verify the geometry of your consumable.

The 10-Second “Flare Test”: Catch Cardboard Bobbin Defects Before They Eat Your Rotary Hook

What you’re checking: Whether the cardboard sides are flaring outward (even by a fraction of a millimeter).

How to perform the Sensory Check:

1. Visual Anchor: Hold the bobbin at eye level. Do not look down at it; look through the profile.
2. Action: Rotate it slowly between your fingers.
3. Success Metric: The cardboard flanges should look flat and parallel, like a coin. If they look like a saucer or a shallow bowl, the bobbin is defective.

If the cardboard is flared, the rule is absolute: discard it immediately. Do not try to squash it flat. Do not save it for a "rush job."

Why am I so strict? Because a flared bobbin creates a variable friction coefficient. As the machine speeds up, heat builds, the cardboard swells, and tension spikes unpredictably. You cannot "tune" your way out of bad hardware.

What problems can a flared bobbin cause?

Mike lists several symptoms that manifest when cardboard rubs the hook. If you see these, stop and check the bobbin first:

• Ghost Breakage: Unexpected thread breaks with no burrs on the needle.
• Fraying: The thread looks "fuzzy" or shredded before it snaps.
• The "Pop-Out": Thread pulling up out of the needle eye right after a trim.
• Hat Disasters: Needle breaks specifically when running caps (due to the tighter tolerances).
• Column Variation: Satin columns looking wider or narrower than the digitizing file.

Warning: (Mechanical Safety) If you suspect the bobbin is rubbing the rotary hook, stop the run immediately. Continuing to sew through friction issues can escalate from thread breaks to catastrophic needle breaks. Flying needle shards are a serious eye and hand hazard. Always wear protective eyewear when troubleshooting.

The Numbers That Settle Arguments: Correct Bobbin Tension on a Towa Gauge (180–200)

"Feeling" tension by hand is an art, but in a production environment, we trust data. Mike gives a clear target range when measuring bobbin tension with a Towa gauge (TM-1 or TM-3).

The Golden Range (Empirical Data)

• Target Tension: 180gf – 200gf (grams-force).
  • Note: On some gauge scales, this reads as 18 – 20.
• The Danger Zone: Readings of 300 – 600 (or 30 – 60) indicate a jam, dirt, or the "flare" friction mentioned above.

Why this specific range? A tension of 180-200 provides enough drag to pull the top thread down for a crisp knot, but not so much that it causes "puckering" (wrinkling) on delicate fabrics.

The “Hidden” Prep Pros Do Before Testing Bobbin Tension (So the Reading Means Something)

Before you snap anything into a gauge, you must perform a "Pre-Flight Check." Testing a dirty case gives you false data, leading to bad adjustments.

Prep Checklist (Do this BEFORE every Towa test)

1. Consistency Check: Confirm you’re testing the same bobbin type (e.g., Coats, Filtec, Neb) you intend to run. Don't mix brands.
2. The "Eye-Level" Pass: Visually inspect the bobbin for flare. Discard failures.
3. Debris Hunt: clear the bobbin case. Use a business card corner or weak air blast to clean under the tension spring.
   • Sensory Check: Lint packed under the spring feels like "cushioning" and prevents the spring from closing, causing zero tension.
4. Oil Control: If you recently oiled the hook assembly, wipe the case dry. Excess oil is the enemy of cardboard bobbins.

HINT: Keep spray air and a cleaning brush next to your tension gauge. It reminds you to clean before you measure.

Load the Bobbin the Way Mike Does: Thread Direction First, Then the Case

This is where 50% of "tension issues" originate: simple loading errors.

1) Orient the bobbin thread correctly (The "Waterfall" Method)

Mike’s method is non-negotiable for consistency:

• Hold the bobbin in your left hand.
• Pull the tail with your right hand.
• Visual Check: The thread must unwind off the top of the bobbin, cascading away from you like a waterfall.

2) Insert the bobbin into the bobbin case

• Place the bobbin into the metal case.
• Slide the thread through the slit.
• Auditory/Tactile Check: Pull the thread under the tension leaf spring until you hear a sharp "Click" or feel it snap into the detent. If you don't feel this, the thread is not seated, and you have zero tension.

The Pigtail Trap: Why You Must NOT Use the Bobbin Case Pigtail During Towa Testing

This is the most common mistake rookies make. A commenter asked: “Why aren’t you using the pigtail?”

The Rule: The pigtail (that curly wire loop) adds extra friction geometry that is part of the sewing path, not the measuring path.

The Protocol:

• For Sewing: Thread through the slit, under the spring, AND through the pigtail.
• For Towa Gauge Testing: Thread through the slit, under the spring, and STOP. Do not run it through the wire pigtail loop.

Testing through the pigtail will give you artificially high readings, causing you to loosen the screw too much. Result? Loose loops on the back of your garment.

The Towa Gauge Routine: Snap In, Thread the Wheels, Pull Smooth (No Jerking)

Now you are ready to measure data.

Step-by-step: Testing bobbin tension with a Towa gauge

1. Snap the bobbin case into the Towa gauge. ensure it sits flush.
2. Route the Path: Guide the thread under the bottom wheel and over/around the top pulley exactly as shown in the diagram.
3. The "Smooth Pull": Pull the thread downward (South) at a slow, constant speed.
   • Sensory Check: Imagine you are pulling dental floss. You want consistent resistance. Do not jerk the thread like you are starting a lawnmower.

Reading the Data (Success Criteria)

• The "Settle": The needle will jump initially. Ignore the jump. Watch where it settles while you are pulling.
• Target: A stable needle hovering between 180 and 200.
• Failure Mode 1 (Spikes): Needle jumps to 300+. Cause: Bobbin flare or dirt.
• Failure Mode 2 (The Drop): Needle holds at 180, then suddenly drops to 50, then back to 180. Cause: Warped Bobbin. The bobbin is wobbling inside the case. Discard it.

The Mechanical “Why”: Where the Bobbin Rubs the Rotary Hook (And Why It Feels Like Tension)

Mike physically identifies the specific friction point.

The Physics of Failure: The rotary hook spins at 1,000+ RPM. The bobbin sits still (mostly). If the cardboard flares, it touches the back wall of that spinning hook. This turns your bobbin into a brake pad. The machine tries to pull thread, encounters massive friction, and snaps the thread. This is why tightening or loosening the tension screw does nothing—the screw isn't the problem; the brake pad is.

Symptoms You’ll See on the Floor (and the Fast Fix That Saves the Day)

Use this "Symptom Map" to diagnose issues without guessing.

1) Unexpected thread breaks / Fraying

• Likely Cause: Defective bobbin flare rubbing the hook.

2) Needle breaks on Caps/Hats

• Likely Cause: Excessive friction tension on the bobbin. Hats are rigid; they don't give. When tension spikes, the needle deflects and hits the needle plate.

3) Inconsistent column widths (Sawtooth edges)

• Likely Cause: Warped bobbin (tension fluctuates low-high-low).

4) Cardboard Swelling

• Likely Cause: Over-oiling. Oil migrates into the cardboard, making it expand like a wet sponge.

A Decision Tree You Can Hand to Staff: Fabric/Job Type → What to Check First

In a commercial shop, speed comes from standardized decisions. Print this for your operators.

Decision Tree (Quick Triage):

1. Is the job high-risk (Caps, thick leather, expensive jackets)?
   • YES: Mandatory Pre-Check. Inspect bobbin flare + Confirm tension (180–200) on the gauge.
   • NO: Proceed to step 2.
2. Did the problem start within 5 minutes of a bobbin change?
   • YES: It's the bobbin. Stop. Perform flare test. Re-test tension.
   • NO: Go to step 3.
3. Is the satin column width changing?
   • YES: Bobbin wobble. Discard bobbin.
   • NO: Go to step 4.
4. Was the machine just oiled?
   • YES: Check for oil-soaked cardboard. Wipe case dry.
   • NO: If bobbin passes all checks, inspect the Top Thread Path (Needle burr, tree alignment).

The Two-Bobbin-Case Rotation Strategy: The Small Habit That Prevents Big Downtime

Mike recommends a "Pit Stop" workflow: Keep one bobbin case in the machine and one on the bench.

While the machine is stitching Bundle A:

1. Clean the spare case.
2. Load a new bobbin.
3. Test it on the Towa gauge (verify 180-200).
4. Stage it.

When the machine runs out, swap instantly. This eliminates the "I'll just guess the tension because I'm in a hurry" error.

This is how you scale. Investing in spare bobbin cases is cheap insurance for commercial embroidery machines.

Magnetic Bobbins, Compatibility, and What I’d Do in a Mixed-Machine Shop

A reader asked about using magnetic-core bobbins (like Filtec).

The Expert Verdict: Magnetic bobbins are excellent for maintaining consistent tension as the bobbin empties, but they are not universally compatible with the "check spring" in every machine’s bobbin sensor system.

Action:

• If you have a melco amaya embroidery machine or the newer melco emt16x embroidery machine, test a small batch first.
• Monitor the "Bobbin Empty" sensor. If the magnet interferes with the sensor, the machine may not stop when the bobbin runs out.
• Consistency is King: Do not mix magnetic and standard bobbins on the same head. Choose one system and calibrate your tension gauge to it.

The Upgrade Path (Without the Hard Sell): When Hooping Speed Becomes Your Real Bottleneck

This guide has focused on bobbins, but the business pain is lost production time.

Once you stabilize your tension (Good Bobbins + Towa Gauge verification), the next bottleneck you will hit is hooping. If your machine is running perfectly but your operator takes 5 minutes to frame a shirt, your profitability dies.

The "Upgrade" Logic:

• Trigger: You see "hoop burn" (ring marks) on delicate polos, or your wrists hurt from prying frames open.
• Criteria: If you are doing production runs of 20+ items, screw-tightening hoops are too slow.
• Option: Upgrade to Magnetic Hoops.

Magnetic frames (compatible with specific melco mighty hoop systems or third-party equivalents like SEWTECH magnetic frames) self-adjust to fabric thickness. They eliminate the need to adjust screws between a T-shirt and a hoodie.

For larger jacket backs, utilizing a melco xl hoop style magnetic frame ensures the fabric is held taut without the struggle, ensuring your perfect tension actually results in a perfect design.

Warning: (Magnetic Safety) Magnetic hoops aid production speed but contain powerful Neodymium magnets.
* Pinch Hazard: Keep fingers clear of the snapping zone.
* Health Safety: Operators with pacemakers or insulin pumps must maintain a safe distance (usually 6-12 inches) or avoid handling them directly. Check device manuals.

Operation Checklist: The “No More Mystery Breaks” Routine

Copy this to your shop floor clipboard:

• Inventory: Inspect every new box of bobbins with the Eye-Level Flare Test. Quarantine bad batches.
• Diagnosis: When thread breaks, Towa test the bobbin WITHOUT the pigtail.
• Target: Verify 180gf – 200gf (Steady pull).
• Rejection: If the gauge needle wobbles or drops, discard the bobbin.
• Hygiene: Wipe the bobbin case dry before loading; avoid oil swell.
• Workflow: Use the Two-Case Rotation system to pre-tension bobbins while the machine runs.

By following this routine, you stop "chasing ghosts" and start trusting your machine again.

FAQ

• Q: On Melco commercial embroidery machines, what is the fastest check when thread breaks start right after a bobbin change?
  A: Do the 10-second eye-level bobbin “flare test” and discard any cardboard-sided bobbin that is not flat and parallel.
  • Hold the bobbin at eye level and rotate it slowly between fingers.
  • Compare the side profile: flat/parallel like a coin = OK; saucer/bowl shape = defective flare.
  • Stop the run immediately if flare is suspected to avoid escalating into needle breaks.
  • Success check: the cardboard flanges look straight and parallel through the full rotation.
  • If it still fails: clean the bobbin case area and verify bobbin tension on a Towa gauge before touching any tension screws.
• Q: What bobbin tension range should a Melco rotary hook setup show on a Towa TM-1 or TM-3 gauge?
  A: Aim for 180–200 gf (often shown as 18–20 on some scales) during a smooth pull.
  • Snap the bobbin case into the Towa gauge and route the thread under the lower wheel and over/around the top pulley.
  • Pull downward slowly and steadily (no jerking) and ignore the initial needle jump.
  • Success check: the needle settles and stays stable between 180 and 200 while pulling.
  • If it still fails: readings in the 300–600 range point to flare friction, dirt, or a jam—clean the case and re-test with a known-good bobbin.
• Q: What “pre-flight” steps are required before testing Melco bobbin tension on a Towa gauge so the reading is meaningful?
  A: Clean and standardize first—testing a dirty or mixed-brand setup gives false data.
  • Confirm the same bobbin type/brand you intend to run (do not mix brands during testing).
  • Inspect the bobbin for flare at eye level and discard any failures.
  • Clear lint from the bobbin case, especially under the tension spring (a business card corner or weak air blast works).
  • Success check: the thread path under the spring feels crisp (not cushioned by lint) and the case is wiped dry if oil was applied recently.
  • If it still fails: re-test with a different bobbin to rule out wobble/warp before adjusting the tension screw.
• Q: How should a Melco bobbin be oriented and seated in the bobbin case to avoid “zero tension” and immediate stitch problems?
  A: Load the bobbin in the “waterfall” direction and make sure the thread clicks fully under the tension spring.
  • Hold the bobbin in the left hand and pull the tail with the right hand so thread unwinds off the top, cascading away like a waterfall.
  • Insert the bobbin into the metal case and slide the thread through the slit.
  • Pull the thread under the tension leaf spring until it snaps into place.
  • Success check: a sharp “click” (or a distinct snap feeling) confirms the thread is seated; no click often means no tension.
  • If it still fails: verify the bobbin tension number on a Towa gauge and inspect for flare or lint under the spring.
• Q: When testing Melco bobbin tension with a Towa gauge, why must the bobbin case pigtail wire loop be skipped?
  A: Do not thread the pigtail during measurement because it adds extra friction and inflates the reading.
  • For sewing: route through slit, under the spring, and through the pigtail.
  • For Towa testing: route through slit and under the spring, then stop (skip the pigtail).
  • Success check: the gauge reading stays in the target range without needing to over-loosen the tension screw.
  • If it still fails: if readings are still high, suspect flare rubbing or debris/jam rather than “too-tight” screw settings.
• Q: On Melco embroidery machines, what does the Towa gauge “needle drop” (180 then suddenly 50 then back) indicate, and what should be done?
  A: Discard the bobbin—this pattern points to a warped bobbin wobbling in the case and causing fluctuating tension.
  • Perform the smooth downward pull and watch the settled reading, not the initial jump.
  • Look for a stable hover vs. a sudden drop-and-recover behavior during the same pull.
  • Success check: a good bobbin produces a steady, consistent reading without sudden dips.
  • If it still fails: re-test with a different bobbin and re-check for flare and cleanliness before investigating the top thread path.
• Q: What safety steps should be followed when Melco embroidery machines show signs of bobbin rubbing (fraying, ghost breaks, or needle breaks on hats)?
  A: Stop immediately and troubleshoot the bobbin/hook friction first—continuing can escalate into dangerous needle breaks.
  • Halt the run as soon as fraying/ghost breaks appear after trims, especially on caps where tolerances are tighter.
  • Replace any suspect flared or oil-soaked cardboard bobbin and clean the hook/bobbin case area.
  • Wear protective eyewear during troubleshooting because needle shards can eject if a needle breaks.
  • Success check: after replacing/cleaning, the machine runs without fraying and the stitch behavior stabilizes right after trims.
  • If it still fails: confirm 180–200 gf on the Towa gauge, then move to inspecting the top thread path (needle condition/burrs, alignment) only after bobbin checks pass.
• Q: In commercial embroidery production, when should operators upgrade from technique fixes to magnetic hoops or higher-capacity SEWTECH multi-needle embroidery machines?
  A: Fix thread stability first, then upgrade when hooping time and hoop burn become the real bottleneck.
  • Level 1 (technique): standardize bobbins, do the flare test, and verify 180–200 gf with a Towa gauge to eliminate “mystery breaks.”
  • Level 2 (tool): switch to magnetic hoops when hoop burn appears on delicate polos or when screw hoops slow runs of 20+ items.
  • Level 3 (capacity): consider SEWTECH multi-needle embroidery machines when the line is stable but overall throughput is limited by production volume needs.
  • Success check: less re-hooping, fewer ring marks, and faster, repeatable loading without sacrificing stitch consistency.
  • If it still fails: standardize one hooping method per job type and keep a two-bobbin-case rotation so tension is verified before the next swap.