A few things to set up before you begin threading that make a big difference to the result.

• Turn the machine off before re-threading
• Raise the presser foot - this opens the tension discs so the thread seats properly
• Set all tension dials to the default or middle setting before threading
• Have your machine manual to hand - threading paths vary between models and going from memory is one of the most common causes of problems

Threading order is critical on an overlocker. Always follow this sequence - threading in the wrong order will prevent the machine from forming stitches correctly.

• Upper looper first
• Lower looper second
• Needles last

Follow the thread path for the upper looper carefully, making sure the thread passes through every guide in the correct order.

• Work slowly through every guide - missing even one can cause thread breaking or poor stitch formation
• Refer to your manual for the exact path on your machine
• The upper looper thread will be visible on top of the fabric in the finished stitch

The lower looper thread path is often the trickiest part of threading an overlocker - take your time and don't rush this step.

• Follow every guide carefully, referring to your manual throughout
• Make sure the lower looper thread passes under the upper looper thread at the correct point - missing this is a very common cause of the machine not forming stitches at all

Thread the needles last, once both loopers are threaded correctly.

• Thread the right needle first, then the left
• Make sure each needle thread passes through the guides on the correct side - right needle thread through the right side guides and left needle thread through the left side guides - this prevents the threads from tangling during sewing
• Thread paths do vary between models so refer to your manual to confirm the correct guides for your machine
• Pull at least 10-15cm of thread through each needle

Before running the machine, check these settings are correct for standard overlocking.

• Make sure the differential feed is set to 1 (neutral) - this is the standard starting point before making any adjustments for fabric type
• Check the stitch finger is engaged - if you've previously been doing a rolled hem the stitch finger may have been disengaged, and forgetting to re-engage it is a very common cause of poor stitch formation
• Refer to your manual if you're unsure how to engage the stitch finger on your specific model

Don't go straight from threading to sewing on fabric - chain off first to confirm the machine is threading correctly.

• Before touching the foot pedal, turn the handwheel manually a few times to check everything is running smoothly and the threads are moving freely
• Then hold all thread tails and run the machine slowly without fabric to form a thread chain
• As the chain forms, gently pull it away from the back of the presser foot - this prevents thread building up underneath and causing a jam at the start of your first seam

Always test on scrap fabric of a similar weight to your project before starting. A well-threaded overlocker should produce a balanced stitch straight away - if not, small tension adjustments will get you there.

• Check the stitch looks balanced on both sides - the loops should wrap neatly around the fabric edge with no loose threads or pulling on either side
• If the stitch doesn't look right, adjust the tension dials gradually and test again - increasing the number tightens the tension and decreasing the number loosens it
• Make small adjustments one dial at a time so you can clearly see the effect of each change

Left: incorrect Right: correct

A balanced overlock stitch wraps neatly around the fabric edge. If your stitch looks like the left side, your tension needs adjusting. See our Overlocker Tension Guide for a full breakdown of how to identify and fix tension problems.