Basic Overlocker Guide – Threading & Using Your Overlocker
An overlocker (also called a serger) trims the fabric edge, overcasts it to prevent fraying, and sews the seam all in one operation. Most domestic overlockers use 3 or 4 threads.
Before You Start
You'll need:
- 3 or 4 cones of overlocker thread
- New overlocker needles (correct type for your machine)
- Tweezers (often supplied with the machine)
- Small scissors
- Scrap fabric for testing
Always:
- Turn the machine off before threading.
- Raise the presser foot.
- Turn the handwheel towards you.
- Raise the needles to their highest position.
Threading the Overlocker
Always thread in the correct order. Most machines follow this sequence:
- Upper Looper
- Lower Looper
- Right Needle
- Left Needle
If the threads are not threaded in this order, the machine may not stitch correctly.
Step 1 – Place the Thread Cones
Place each cone on the spool holders and fit the thread nets or spool caps if required.
Step 2 – Thread the Upper Looper
Follow the colour-coded thread path.
Pass the thread through:
- Thread guide
- Tension disc
- All marked guides
- Upper looper eye
Leave approximately 10–15cm (4–6 inches) of thread behind the presser foot.
Step 3 – Thread the Lower Looper
Again, follow the colour coding.
The lower looper has the most guides and is usually the trickiest thread to install.
Use the tweezers if needed.
Leave another 10–15cm thread tail.
Step 4 – Thread the Right Needle
Follow the needle thread path through:
- Guides
- Tension discs
- Needle bar guides
- Needle eye (front to back)
Step 5 – Thread the Left Needle
Repeat exactly as for the right needle.
Bring the Threads Together
Pull all four threads under the presser foot and towards the back of the machine.
Turn the handwheel one full revolution.
The threads should chain together.
Before Sewing
Test stitch on a scrap of the same fabric.
Check:
- The stitch forms correctly.
- Fabric feeds evenly.
- The knife trims neatly.
- No loops are hanging off the edge.
Basic Controls
Stitch Length
Normally between:
- 2.5–3mm for general sewing
- Longer for thicker fabrics
- Shorter for rolled hems
Differential Feed
Controls stretching or gathering.
Setting 1.0
Normal sewing.
Higher than 1
Prevents stretching on knit fabrics.
Lower than 1
Creates gathers or decorative lettuce edges.
Cutting Width
Adjusts how much fabric the knife trims.
If loops hang off the edge:
- Increase cutting width.
If fabric puckers:
- Reduce cutting width.
Sewing with an Overlocker
- Raise the presser foot.
- Place the fabric under the foot.
- Lower the presser foot.
- Start sewing slowly.
- Guide the fabric gently—do not pull it.
- Let the knife trim only a small amount of fabric.
The feed dogs move the fabric automatically.
Finishing the Seam
When you reach the end:
Continue sewing for approximately 10–15cm (4–6 inches) after the fabric leaves the machine.
This creates a thread chain.
Cut the chain and secure it by:
- Threading it back into the seam with a needle, or
- Using a seam sealant if appropriate.
Common Stitch Types
4-Thread Overlock
- Strong seams
- Knitwear
- Garments
- Most common stitch
3-Thread Overlock
- Edge finishing
- Lightweight fabrics
- Decorative edging
Rolled Hem
Perfect for:
- Scarves
- Napkins
- Chiffon
- Decorative edges
Requires changing the stitch finger (or engaging the rolled hem lever on some machines).
Troubleshooting
| Problem | Possible Cause |
|---|---|
| Won't chain | Incorrect threading order |
| Skipped stitches | Bent or worn needle |
| Thread breaking | Tension too tight or incorrect threading |
| Loops hanging off edge | Increase cutting width or adjust tensions |
| Fabric puckering | Reduce thread tension or cutting width |
| Fabric stretching | Increase differential feed |
| Knife not cutting | Blade worn or switched off |
General Maintenance
- Brush away lint after every project.
- Oil the machine only where recommended in the instruction manual.
- Change needles regularly.
- Replace the upper knife when it becomes dull.
- Keep the machine covered when not in use.
Safety Tips
- Never sew over pins.
- Keep fingers away from the moving knife.
- Turn the machine off before changing needles or threading.
- Always use the correct needle type and size for your fabric.
With a little practice, threading becomes much quicker, and you'll be able to produce strong, professional-looking seams and neatly finished edges on a wide range of fabrics.