Why does an overlocker skip stitches: a complete guide to setting it up

The situation when overlocker skips stitches, is familiar to many sewing masters. Instead of a tight, elastic overlock stitch, the output is a torn edge of the fabric, where the threads lie separately from each other or are completely absent in some places. This is not just an aesthetic defect, but also a serious problem, since the edge of the product remains untreated and can quickly crumble during wear.

Most often, the reason lies in the desynchronization of the needles and loopers. The stitch formation mechanism is extremely precise, and even a minimal deviation in the time of picking up the thread leads to skipping. However, there is no need to panic: in most cases, the defect can be fixed on your own without contacting a service center.

First you need to carry out basic diagnostics. Check that the threads are correct, that the needle number matches the type of fabric, and that there is no visible damage to the point. Often the problem is solved by simply replacing consumables or correctly re-threading the tensioners.

Diagnostics and initial check of needle condition

The first step in eliminating skipped stitches is to carefully check the needle group. Blunt point or microscopic bend may not create enough loop for the looper nose to grip. Even if the needle visually seems intact, it should be replaced with a new one, selected strictly according to the type of fabric being processed.

Pay attention to the needle installation height. If it is set too high or low relative to the standard, the moment of loop formation is shifted. In this case, the needle passes by the catching hook and the thread is not picked up. For different models of overlockers, be it Brother, Janome or Juki, there are tolerances, but the general rule is to install the needle all the way up in the needle holder.

⚠️ Attention: Never use old needles on knitted or stretchy fabrics. Even the slightest roughness at the tip causes the fibers of the fabric to shift and skip stitches.

It is also important to check the type of needle. To work with knitwear and elastic materials, needles with a rounded tip are required (designated as Jersey or SUK). Sharp needles (Sharp or H) are intended for fabrics that do not tend to stretch and can pierce knitwear without forming the correct loop for the looper, which causes skipping.

• 🧵 Replace the needles with new ones, making sure that they are fully raised in the needle holder.
• 🧵 Check that the needle number matches the density of the fabric (for thin fabrics No. 70-75, for thick fabrics No. 90-100).
• 🧵 Make sure the flat side of the needle shank is oriented correctly (usually back or to the side, according to the instructions).
• 🧵 When working with elastic fabrics, use only needles with a rounded point.

Adjusting the interaction between the needle and the lower looper

If replacing the needles does not help, the problem lies deeper - in a synchronization disorder. The moment when the nose of the lower looper approaches the needle is critical. The gap between the point of the needle and the tip of the looper should be minimal, almost zero, but without contact. If the gap is too large, the hinge will slip.

Adjusting this setting requires removing the front cover and possibly the needle plate. While rotating the flywheel by hand, observe the trajectory of movement. At the moment of maximum needle lift, the tip of the looper should pass strictly in the center of the needle groove or close to it. Shifting this moment to the left or right leads to the fact that overlocker skips stitches.

In addition to clearance, vertical stroke is important. If the looper passes too high or low relative to the eye of the needle, the thread cannot be picked up. In some modern models, these parameters are fixed by the factory and do not require intervention, but in professional machines Pegasus or Siruba This is a standard setup procedure.

Upper looper adjustment and stitch formation

The upper looper also plays a key role. Its nose should fit into the loop formed by the lower looper and the needle. If the top element is offset, the thread lies on top of the fabric without braiding the edge. This often looks like a skip, even though the mechanism is technically working but not closing the stitch.

Check the upper looper thread tension. Too much tension can pull the thread out of the gripping area prematurely. Loosen the adjuster and try making a test stitch. Sometimes changing the trajectory of threading through the tension disk helps.

It is important to monitor the condition of the upper looper nose itself. There should be no nicks or soot on it from friction with the thread. The rough surface prevents the thread from sliding freely, causing the loop to form untimely. Polishing or replacing the part solves the problem.

The influence of thread quality and tension on stitch skipping

The quality of the threads used directly affects the stability of the stitch. Cheap threads with uneven twist or nap can get stuck in the tension discs, creating the illusion of correct tension that changes dramatically as you sew. This leads to random omissions.

Use special overlock threads that have a smooth surface and less lint. They glide through mechanisms better and are less prone to tearing. Polyester threads, which have good elasticity, are excellent for working with knitwear.

⚠️ Attention: Never use old, dry threads. They lose strength and elasticity, which is guaranteed to lead to breaks and skipped stitches even with a working overlocker.

The tension should be adjusted gradually, making test stitches after each turn of the adjuster. Remember the positions of the discs for different types of fabrics. For thin materials, the tension is weakened, for dense ones, it is strengthened, but always maintain a balance between the upper and lower threads.

Specifics of working with knitwear and elastic fabrics

Knitwear is the most capricious material for overlocking. Its elasticity requires a special approach. If overlocker skips stitches Specifically on knitwear, most likely it’s a matter of fabric feed speed or presser foot pressure. Pulling too quickly does not give the mechanism time to form a high-quality knot.

Use a Teflon coated foot or a roller foot. They ensure uniform advancement of the fabric without stretching. An ordinary metal foot can “slow down” the bottom layer of fabric, while the top layer stretches, which disrupts the rhythm of the needles.

The secret of working with thin knitwear

Place a strip of thin paper (tracing paper or toilet paper) under the seam. The overlocker will easily pierce the paper along with the fabric, and after sewing the paper can be easily torn off, leaving a perfect stitch without skipping stitches.

It is also worth paying attention to the differential. For elastic fabrics it often needs to be set to a position that prevents stretching (value greater than 1). This ensures a consistent stitch size and prevents edge distortion that causes skipping.

Table of main causes and solutions

To quickly troubleshoot, use the summary table. It will help you organize problems and find a solution that matches your machine's symptoms.

Symptom	Probable Cause	Elimination method
Skipping stitches one at a time	Curved needle point	Replacing the needle with a new one, correct installation
The thread lies on the fabric without overcasting	The interaction of the loopers is disrupted	Adjusting the gap between needle and looper
Gaps on thick seams	Weak foot pressure or dull needle	Increase the presser foot pressure, replace the needle with a thicker one (No. 90-100)
Chaotic passes	Poor thread quality or threading	Replace threads, rethread, clean tensioners

Analyzing the table, it is easy to see that most problems can be solved by replacing consumables or simple adjustments. However, if none of the methods helped, the problem may be wear of the drive gears or shaft deformation, which requires the intervention of a technician.

Prevention and care of the stitch formation mechanism

To overlock worked stably and did not miss a loop, it requires regular care. Dust, lint and thread residues accumulating around the loopers disrupt the adjustment of the mechanism. Brushing and blowing with compressed air should become a weekly habit.

Lubrication is another important aspect. Dry oil increases friction and can slow down moving parts, disrupting timing. Use only special oils for sewing machines, applying them dropwise to the places indicated in the instructions.

Remember to periodically check the screws that secure the needle bar and loopers. Vibration can weaken them, which leads to backlash and, as a result, missing loops. Timely tightening of fasteners will preserve the accuracy of the mechanism.

Why does the overlocker only skip stitches on certain areas of the fabric?

This is often due to uneven seam thickness or changes in fabric structure. In places of thickening (seams, joints), the needle may deflect, changing the moment of loop formation. It may also be due to insufficient presser foot pressure, which causes the fabric to sag in these places.

Can incorrect threading cause skipped stitches?

Yes, this is one of the most common reasons. If the thread bypasses even one tension disk or does not lie correctly in the thread take-up lever, the tension is broken. The thread becomes too loose or, conversely, too tight, which prevents the looper from grasping it correctly.

How often do you need to change needles in an overlocker?

Professionals recommend changing needles after every 8-10 hours of continuous work or when starting a new project. For home use, it is enough to change the needles after each large order or when the first signs of dullness appear (the fabric begins to “stretch” under the needle).

Does sewing speed affect the formation of skipped stitches?

Yes, if the flywheel rotation speed is too high, the mechanism may not have time to form a stable loop, especially on cheap overlocker models. Reducing the speed often helps eliminate the defect. The smoothness of pressing the pedal is also important.