Sewing machine loops from below: 7 reasons and step-by-step repair

Problem with looping the thread from below - one of the most common malfunctions of sewing machines, which both beginners and experienced craftsmen encounter. The defect manifests itself in the form of chaotic loops on the wrong side of the fabric, uneven stitches, or even a break in the bottom thread. Most often, the reason for this is incorrect adjustment of the mechanisms, but sometimes the reason lies deeper - in wear of parts or factory defects.

Many people mistakenly believe that looping is associated only with bottom thread or a bobbin case, but in practice the culprits can be the top thread, the needle, or even the fabric itself. In this article we will look at all possible reasons, from basic to hidden, and we will give step-by-step instructions for eliminating the defect. We will pay special attention mechanical machines (Podolsk 142M, Chaika 134) and electronic models (Janome, Brother), as their setup has key differences.

If you have never repaired sewing machines, don't worry: 80% of problems are solved without disassembling the mechanism. It is enough to understand the logic of the shuttle unit and learn how to properly balance the tension of the threads. But there is good news: even in difficult cases (hook wear, crooked needle stroke), repairs will cost less than buying new equipment.

Before starting diagnostics, prepare:

• 🔧 Screwdriver (flat and Phillips)
• 🧵 Threads of different colors (for dough)
• 📏 Ruler or square
• 🔍 Magnifying glass (for inspecting the needle and shuttle)
• 🧴Machine oil (if lubrication is required)

And remember: Each machine model has its own “weak points”. For example, in Janome The tension regulator is often clogged with dust, and in Singer older series, the bobbin case spring wears out. We will also take these nuances into account.

1. Diagnosis of the problem: how to determine the source of looping

First step - visual stitch analysis. Looping from below can look different:

• 🧶 Large loops - the lower thread “comes out” to the front side, the upper one lies flat.
• 🌀 Tangled Knots - both threads intertwine into a chaotic lump under the fabric.
• 🖇️ Skipped stitches - the lower thread is not caught, the upper thread lies separately.

Each type of defect indicates its cause. For example, large loops almost always associated with loose upper thread tension or incorrect refueling. A tangled knots they talk more often about problems with bobbin case or shuttle mechanism.

Swipe thread balance test:

1. Take two pieces of fabric (cotton or linen) and sew in a straight line.
2. Pull the fabric in different directions: if the stitch “unravels”, then one of the threads is too loose.
3. Inspect the underside: the perfect stitch should look like two intertwined threads without loops.

If the test shows an imbalance, proceed to check thread tension. Start from the top - it's easier and faster.

2. Adjusting the upper thread tension: step-by-step instructions

Incorrect upper thread tension - reason number 1 for looping from below. In 60% of cases, the problem is solved by adjusting the regulator, which is usually located on the front panel of the machine (on the right or top).

How to adjust correctly:

1. Set the tension control to the middle value (usually this is the number 3–4 on the scale).
2. Thread the upper thread according to the instructions for your model (e.g. Brother LS-2125 The thread path is indicated on the body).
3. Sew a test stitch on a piece of fabric. If the loops remain, increase tension by 0.5–1 unit and repeat the test.

Make sure that the thread goes through all the guides|Check that the thread does not catch on the body|Remove old thread from the thread take-up|Check that the spool is positioned correctly (threads converge counterclockwise)-->

Important nuance: on electronic machines (Janome DC2101, Bernina 350) The tension can be adjusted automatically depending on the selected stitch. If the problem persists after manual configuration, reset the settings to factory defaults (Menu → Reset).

If increasing the tension does not help, inspect thread take-up (metal “hook” above the needle). Sometimes it gets clogged with dust or threads. To clean:

1. Raise the presser foot and needle to the highest position.
2. Remove the housing cover (if accessible).
3. Blow out the thread take-up with compressed air or gently clean with a brush.

3. Problems with bobbin case and bobbin thread

If the upper thread is set correctly, but the loop remains, the culprit is bobbin case or lower thread. Let's start with the bobbin:

• 🔄 Incorrect fueling: The thread should come off the bobbin clockwise (for most models).
• 🧲 Cap dirty: Dust and lint block the thread.
• 🔧 Spring wear: If the cap is older than 5 years, the spring may have stretched.

How to clean the bobbin case:

1. Remove the bobbin and cap from the hook.
2. Remove threads and dust from the cap groove (use a toothpick or needle).
3. Check the spring: if it does not fix the thread, the cap needs to be replaced.

For machines with vertical shuttle (Chaika 132, Podolsk 142) there is a separate nuance: the cap must fit into the shuttle until it clicks. If it dangles, looping is guaranteed.

How to check the bobbin case spring?

Take the cap without the bobbin and press the spring with your finger. If it does not return to its original position or weakly fixes the thread, the part must be replaced. For a temporary solution, you can place a thin washer (0.5 mm) under the spring, but this will not last long.

Also check bobbin thread tension:

• Insert the filled bobbin into the cap.
• Hold the cap by the “tail” of the thread and pull lightly: the thread should come off with little effort (as when unwinding a spool).
• If the thread comes off too easily, tighten the screw on the cap (on some models it is hidden under a plastic cover).

4. The Needle: The Hidden Culprit of Looping

A poor-quality or incorrectly installed needle can cause looping, even if everything else is set up perfectly. Check:

• 🔍 Needle type: for thin fabrics (silk, chiffon) use needles 70/10, for jeans - 90/14 or 100/16.
• 📏 Position: the needle must be inserted all the way (the shoulder of the needle rests against the stop).
• 🔄 Wear: The needle becomes dull after 8–10 hours of use. Check the tip for burrs.
• 🧲 Curvature: Place the needle on the table - if it does not lie flat, replace it.

Critical error: Using a needle with curved point. This causes the upper thread not to enter the hook and the lower thread not to be caught. The result is skipped stitches and loops.

For machines with automatic needle threader (Brother Innov-is, Juki HZL-F600) there is one more nuance: the needle must be installed flat side back (to the body of the machine). If the orientation is mixed up, the thread will get caught in the mechanism.

5. Shuttle mechanism: when in-depth diagnostics are needed

If all the previous steps did not help, the problem lies in shuttle mechanism. This is a more complex repair, but you can do it yourself.

Signs of shuttle malfunction:

• 🔊 Extraneous sounds (creaking, knocking) during operation.
• 🌀 Uneven running — the shuttle “sticks” in extreme positions.
• 📉 Stitch offset - the line goes sideways.

For diagnostics:

1. Remove the needle plate and bobbin case.
2. Turn the handwheel by hand and watch the shuttle move. It should move smoothly, without play.
3. Check the gap between the hook and the needle: at the moment of piercing the fabric, the needle should drop to 1.5–2 mm below the shuttle.

Common problems and solutions:

Symptom	Reason	Solution
The shuttle catches the needle	Needle bar offset or hook wear	Adjust the needle position or replace the hook
The thread breaks in the shuttle	Burrs on the shuttle surface	Sand with sandpaper (1000 grit)
The shuttle does not catch the thread	Weak hook spring or worn spout	Replace shuttle or spring
Knock during operation	The shuttle mount is loose	Tighten the fastening screws

For machines with horizontal shuttle (Janome, Bernina) a common problem - shuttle stroke offset. To fix:

1. Loosen the two hook screws (located under the needle plate).
2. Adjust the position of the hook so that the gap between it and the needle is 0.1–0.3 mm.
3. Tighten the screws and check the stitching.

6. Effect of fabric and thread on looping

Sometimes the problem lies not in the machine, but in materials. For example:

• 🧵 Low quality threads (especially cotton ones) can delaminate and get stuck in the mechanism.
• 👗 Fabrics that are too stretchy (stretch, jersey) require a special needle (ballpoint) and weakened tension.
• 🧶 Thick threads (for example, for embroidery) may not fit into the eye of the needle, creating additional friction.

Recommendations for the selection of materials:

• For thin fabrics (batist, silk) use threads #50–60 and an igloo 60/8.
• For dense fabrics (jeans, tent) - threads #30–40 and an igloo 90/14–110/18.
• For elastic materials - threads Maxi-Lock or Serger with a needle ballpoint.

If you sew multilayer products (e.g. jackets), looping can occur due to the lower layers of fabric "pulling" on the stitch. In this case:

1. Increase stitch length to 3–4 mm.
2. Use upper conveyor (if included).
3. Place a sheet of thin paper under the presser foot to reduce friction.

7. Prevention: how to avoid looping in the future

To prevent the problem from recurring, follow these simple rules:

• 🧹 Cleaning: After each project, remove dust from the hook and thread take-up.
• 🛢️ Lubrication: Once every 6 months, dab some machine oil on the moving parts (but not on the thread!).
• 📖 Instructions: Keep your machine manual - it contains recommended settings for different fabrics.
• 🔧 Service: Have your machine professionally adjusted every 2-3 years (especially if it is used daily).

For machines with electronically controlled (Brother CS6000i, Singer Quantum) useful to do factory reset once every six months. This prevents software glitches that can also cause looping.

If you sew often different types of fabrics, keep a notebook with notes:

• What threads and needles did you use?
• Tension settings for each material.
• Features (for example, “denim - long stitch, top tension 4.5”).

This will save time on repeat projects.

FAQ: Frequently asked questions about looping thread

Why does looping appear only on thick fabrics?

On dense materials (jeans, drape), it is more difficult for the needle to pierce the layers, which is why the upper thread does not have time to grab the lower one. Solution:

• Use a needle 100/16 or 110/18.
• Increase stitch length to 3.5–4 mm.
• Loosen the upper thread tension by 0.5–1 unit.

The machine loops after changing the needle. What's the matter?

Most likely the needle is installed not all the way or not that type. Check:

• The shoulder of the needle should rest against the stopper.
• Elastic fabrics require a needle ballpoint, for skin - leather.
• If the needle is crooked, even by 0.5mm, it will cause looping.

Is it possible to repair the shuttle yourself?

Depends on the problem:

• ✅ Burrs - can be cleaned with sandpaper.
• ✅ Offset - You can adjust the screws.
• ❌ Cracks or chips - replacement only.
• ❌ Spout wear — requires turning work (it’s cheaper to buy a new one).

For cars Podolsk and seagull the shuttle is standing 300–500 ₽, for Janome/Brother — 800–1500 ₽.

The looping appeared after cleaning the machine. What to do?

You probably messed up the settings or assembled the mechanism incorrectly. Check:

• Is the bobbin case inserted correctly (should click).
• Are the shuttle screws overtightened (this blocks its movement).
• Is there any grease on the thread or fabric (wipe with alcohol).

If you are unsure, refer back to the assembly instructions.

How to check that the problem is in the lower thread?

Take the test:

1. Take out the bobbin and sew without bobbin thread (top only).
2. If the upper thread lies evenly, the problem is in the bobbin case or the lower thread.
3. If the upper thread loops, the needle or upper thread tension is to blame.