Overlock skips stitches: causes and solutions

Skipping stitches on an overlocker is one of the most common problems faced by both beginners and experienced craftsmen. This malfunction not only spoils the appearance of the seam, but also reduces the strength of the fabric joint, which is critical for products subject to high loads (for example, car covers, upholstery or workwear). Unlike household sewing machines, an overlocker works with several threads at the same time, which means there can be much more reasons for failures.

In this article we will look at 7 Key Reasons for Skipping Stitches, from the banal (improper threading) to the technical (wear of the looper or needle), and we will also give step by step instructions to eliminate them. We will pay special attention to the nuances that are relevant for overlockers used in car repair shops and workshops for sewing car accessories - for example, working with dense fabrics such as cordura or vinyl artificial leather. If your overlocker begins to “spit” stitches or forms long gaps in the seam, read on: most likely, solving the problem will take no more than 20 minutes.

1. Incorrect threading

Before 70% of skipped stitches associated with errors when threading. Overlocking requires strict adherence to the threading pattern, where each thread must pass through its own guides, tensioners and loopers. If any thread is threaded incorrectly—for example, bypassing the tensioner or lying on top of the looper instead of going under it—the machine will skip stitches or create “knots” on the wrong side.

Typical mistakes:

• 🧵 The thread does not pass through tensioner (especially relevant for the top and bottom threads).
• 🔄 The thread is threaded in the opposite direction (for example, from the spool not counterclockwise, but along it).
• 🎯 The thread got into the gap between the looper and the needle, blocking the formation of the loop.
• 🔀 The threads are mixed up (for example, the left thread is threaded like the right one).

How to check:

1. Turn off the overlocker and remove all threads completely.
2. Following the instructions for your model (for example, Brother 1034D or Juki MO-644D), thread one thread at a time, starting from the top.
3. Make sure that the thread slides freely in the tensioner - pull it manually.
4. Check that the thread is passing through under the looper, and not above it.

⚠️ Attention: On overlockers with automatic threading (for example, Janome 9300DX) errors occur less frequently, but are still possible. If the problem persists after refilling, check thread tension — it must be balanced for all threads.

2. Worn or damaged needle

The needle is the most vulnerable element of the overlock machine. When working with thick fabrics (for example, car upholstery or tarpaulin) it dulls or bends 3–5 times faster than when sewing lightweight materials. A dull or bent needle does not pierce the fabric cleanly, but “tears” it, which is why the loop from the looper does not fall into the eye of the needle at the right moment - this is how gaps are formed.

Signs of needle wear:

• 🔍 They remain on the fabric puffs or gusts instead of a neat puncture.
• 📏 Needle visually bent (check by placing it on a flat surface).
• 🔴 There is a needle on the ear burrs or scratches.
• 🕒 The needle is used longer 8–10 hours of continuous operation (service life under intensive use).

How to fix:

1. Replace the needle with a new one suitable for your fabric. For dense materials (for example, leatherette) use needles 90/14 or 100/16 with reinforced point.
2. Make sure the needle is inserted all the way and secured with a screw.
3. Check that the needle matches the brand of overlocker (for example, for Pfaff Hobbylock 2.0 needles fit 130/705H).

3. Thread and fabric mismatch

Skipping stitches often occurs due to imbalance between thread and fabric thickness. For example, if you are sewing thick Corduran thin polyester thread #40, it may tear or not form a loop large enough to be grasped by the looper. And vice versa: the thread is too thick (for example, #12) will create excess friction in the eye of the needle, interfering with its movement.

Recommendations for selecting threads:

Fabric	Recommended thread	Thread thickness	Needle type
Cotton, linen (light)	Polyester or cotton	#50–#60	80/12
Jeans, canvas	Polyester with wax	#30–#40	90/14–100/16
Vinyl leather, leatherette	Polyester or nylon	#20–#30	110/18
Insulation materials (sintepon, holofiber)	Polyester with silicone coating	#40–#50	80/12–90/14

If the thread tears or fluffs while sewing, try:

• 🧵 Reduce the tension of the upper thread by 0.5–1 unit.
• 🔄 Use thread with silicone coating (for example, Gütermann Mara 70).
• 💧 Apply a drop machine oil on the thread before threading (relevant for old overlockers).

4. Problems with the looper

The looper is the “heart” of the overlocker, responsible for capturing the loop from the needle and forming the overlock stitch. If the looper dirty, bent or worn, he does not have time to grab the loop at the right moment, which leads to omissions. This happens especially often when working with “sticky” materials (for example, genuine leather or PVC film), which leave a residue on the looper.

How to diagnose a faulty looper:

• 🔍 Visually inspect the looper for burrs, dents or signs of corrosion.
• 🧲 Check if not magnetized there is a looper (a sign of metal shavings inside the mechanism).
• 🎯 Make sure the looper moves freely in the grooves without jamming.
• 🔧 Check the fastening of the looper - it should not “dangle”.

Cleaning and adjusting the looper:

1. Remove the needle plate and looper (instructions are in the manual for the overlocker).
2. Clean the looper from dirt and threads using soft brush and WD-40 (do not use abrasives!).
3. Lubricate the looper mechanism machine oil (1-2 drops).
4. Adjust the position of the looper relative to the needle (this may require adjusting key).

⚠️ Attention: If the looper is bent, it must be replaced. Trying to “straighten” it yourself will lead to even more skipped stitches. For overlockers Juki and Brother original loopers cost from 1,500 to 3,000 rubles.

5. Incorrect thread tension

Uneven thread tension is one of the most insidious causes of skipped stitches because it is difficult to diagnose visually. If the upper thread tension is too weak, the needle loop does not form correctly and the looper does not “see” it. If the tension of the lower threads (looper) is too strong, they will tighten the loop, preventing it from closing.

How to adjust tension:

1. Start with basic settings: Set all tensioners to the average value (usually 3–4 on a scale).
2. Sew a test stitch on a piece of your fabric. Ideal seam:
   • 🔹 On the front side the stitches are even, without loops.
   • 🔹 On the wrong side the threads are intertwined in the center (do not reach to one of the sides).

If stitches are skipped:

• 🔄 Increase tension upper thread by 0.5–1 unit.
• 🔄 Reduce tension lower threads (looper) by 0.5 units.

Set all tensioners to medium (3–4)

Sew a test seam on a piece of fabric

Check the front side for evenness of stitches

Make sure that on the wrong side the threads intertwine in the center

Adjust the tension of the upper thread when skipping -->

For thick fabrics (eg car upholstery) may be required increase the tension of all threads by 1–2 units. If after adjustment the gaps remain, check needle and looper synchronization - may require professional setup.

6. Contamination or wear of the mechanism

An overlocker, like any sewing machine, requires regular maintenance. Dust, thread fragments and fabric particles accumulate in the mechanism, making it difficult for the needle and looper to move. Overlockers that work with fleecy materials (for example, velor or fleece) or synthetic fabrics that generate dust when cutting.

Signs of mechanism contamination:

• 🔊 Overlock works louder than usual.
• 🔄 The needle or looper moves jerkily.
• 🧹 Accumulates under the needle plate fluff or thread.
• 🔥 Car overheats during long-term work.

How to clean an overlocker:

1. Unplug the machine and remove needle plate.
2. Remove visible debris soft brush or a vacuum cleaner with a narrow nozzle.
3. Wipe the mechanism dry cloth, soaked in alcohol solution (do not use water!).
4. Lubricate rubbing parts machine oil (1-2 drops for each moving unit).
5. Check drive belt - it should not be stretched or cracked.

What are the dangers of working on a dirty overlocker?

In addition to skipping stitches, contamination of the mechanism leads to:

- Accelerated wear of the needle and looper (2–3 times faster).

- Overheating of the engine, which can cause failures in the electronics (on models with digital control, for example, Janome 6234XL).

- Breakdown of gears, the repair of which costs 5,000–10,000 rubles.

7. Electronics malfunctions (for computerized models)

Modern overlockers (for example, Brother 1034D or Juki MO-2000QVP) are equipped with electronic control units that regulate the speed of movement of the needle and looper. If the electronics fail, the synchronization is disrupted and the looper does not have time to capture the loop from the needle. This manifests itself as random stitch skipping, which cannot be eliminated by mechanical adjustment.

Signs of electronic faults:

• 🔌 Overlock spontaneously changes speed.
• 🔄 appears on the display errors (for example, E6 on Janome).
• 🔊 The machine makes beeping sounds when turned on.
• 🔋 Skipped stitches occur only at high speeds.

What to do:

1. Restart the overlocker (unplug for 1-2 minutes).
2. Check surge protector - Voltage surges can disrupt settings.
3. Update the firmware (relevant for models with a USB port, for example, Pfaff Coverlock 3.0).
4. If the error persists, contact your service center - replacement may be required control boards.

💡

Electronic faults are almost never fixed on your own. If the overlocker is under warranty, do not disassemble it - this will void the warranty.

FAQ: Frequently asked questions about skipping stitches on an overlocker

Can I use regular sewing needles for overlocking?

No, overlocking requires special needles with flat flask (for example, 130/705H or ELx705). Regular sewing machine needles (eg. HAx1) are not suitable - they can damage the mechanism or break during operation.

Why does the overlocker skip stitches only on thick fabrics?

Most likely the problem is insufficient needle penetration force. Try:

• Set the needle thicker (for example, 110/18 instead of 90/14).
• Reduce sewing speed.
• Use wax-coated thread to reduce friction.

How often should you clean your overlocker?

Depends on intensity of use:

• 🏠 Home use (1–2 times a week): cleaning once every 3 months.
• 🏭 Professional use (daily): cleaning once a month + lubricating every 2 weeks.
• 🚗 Working with thick fabrics (tarpaulin, leatherette): cleaning after every major project.

Can I repair the looper myself?

Depends on the nature of the malfunction:

• ✅ Cleaning and Lubrication - you can do it yourself.
• ✅ Replacing the looper - possible if you have experience in disassembling an overlocker.
• ❌ Repairing a Bent Looper - not recommended as it requires precise calibration.

For models Juki and Brother Loopers are sold complete with replacement instructions.

Why are there still skipped stitches after changing the needle?

Possible reasons:

• 🔄 Needle installed not all the way or not secured with a screw.
• 🧵 The thread does not match the thickness of the needle (for example, thin thread #60 in the needle 110/18).
• 🔧 The looper is not adjusted to the new needle (synchronization is required).
• 🧲 Remained in the mechanism scraps of old threadblocking movement.

Check all the points in order.