Sewing Machines & Needles
Serger / Overlock
An overlocker cuts as it sews. A moving knife trims the seam allowance to a fixed width and the loopers wrap the raw edge in thread at the same time, which is why it is the fastest way to finish a seam and the most frustrating to thread. It is a finishing machine, not a construction machine: it makes seams that stretch, not seams that hold a shaped garment together.
| Specification | Value |
|---|---|
| Threads | 3 or 4, some convert to 2 |
| Stitch width | 3 - 7 mm |
| Differential feed | 0.7 - 2.0 ratio |
| Cutting knife | Upper and lower, replaceable |
| Stitch length | 1 - 4 mm |
| Speed | 1000 - 1300 stitches per minute |
Technical parameters
| Parameter | Detail |
|---|---|
| Looper threading | Lower and upper, order matters |
| Tension dials | Four, colour-coded to the thread path |
| Presser foot | Standard, plus a rolled-hem foot |
| Rolled hem | Requires 3-thread conversion |
| Consumables | Knives and needles wear together |
| Weight | 6 - 9 kg |
Safety
The cutting knife is sharp and moving. Never reach under the presser foot while the machine is running, and keep the needle plate and knife free of pins. Use the threading tweezers rather than fingers when threading the lower looper.
What it is for
A three- or four-thread overlock machine that trims, stitches and neatens a seam edge in one pass.
Compatible fabrics
Compatible stitches
Working notes
- Thread in the order printed on the machine; the lower looper last.
- Test the stitch on the same fabric, and adjust the differential feed before the tension.
- A rolled hem needs a 3-thread conversion and a tightened stitch width.
- Replace the knife when the edge starts looking chewed, not when it stops cutting.
Related tools
Sewing Machine
A lockstitch machine, mechanical or computerised, that forms the stitch every other technique on this site is built on.
Needle Set
Universal, microtex, jeans and ballpoint needles, and the size-to-fabric table that decides which one belongs in the machine.
Bobbin
The lower thread supply. The wrong bobbin class, or one wound unevenly, breaks the stitch before any setting will fix it.