What are the parts of an industrial overlocker called?

1Machine head

This is the overlocker itself: the body that houses all the mechanisms. Almost all are flatbed and recessed in the table top, with the sewing area on the left.

2Handwheel

The wheel on the right-hand side. On overlockers it is turned away from you, clockwise, the opposite of a lockstitch machine. On many overlockers the stitch length is changed by pressing a button and turning the handwheel to the number you want.

3Thread stand

The thread stand sits behind the machine and holds one cone per thread: three, four or five, depending on the overlocker. At the top it has the guides each thread runs down through.

4Thread guide

The bar and eyelets each thread passes through from the thread stand to its tension unit. On an overlocker each thread has its own path, and missing a guide unbalances the whole stitch.

5Tension units

One tension unit per thread: one for each needle, one for the upper looper and one for the lower looper. On five-thread machines there are also those for the chainstitch needle and looper. If you touch one, the look of the whole overlock changes.

16Presser foot pressure adjustment

The screw on top of the head. It tightens or loosens the presser foot according to the thickness and type of fabric.

15Front cover

The cover at the front that opens to thread the loopers and clean out lint. The machine must not sew with the cover open.

17Oil reservoir

Also called: sump

Industrial overlockers lubricate themselves: the pump takes oil from the reservoir in the base. It has a level indicator that should be checked before starting the shift.

6Needles

One or two needles, depending on the machine. Overlockers use their own needle system, usually DC×27 (also called B-27), with a different butt from flatbed lockstitch needles.

7Presser foot

Also called: foot, presser

Presses the material against the feed dogs, as on a flatbed lockstitch machine. On most overlockers it swings to one side to expose the plate and loopers.

8Needle plate

The plate the needles go down through. It has the stitch tongue: the metal finger on which the overlock stitch is formed. The width of the tongue sets the stitch width, which is why the plate is changed when you change width.

9Feed dogs

Also called: feed, feeder

The overlocker has two sets of feed dogs: the main feed, behind the needle, and the differential feed, in front. Both move the material on each stitch.

10Differential regulator

It changes how far the differential feed moves compared with the main feed. With more differential the fabric goes in gathered; with less, it stretches. It stops knits and stretch fabrics from going wavy, and can be used to gather on purpose.

11Upper looper

Also called: upper looper

It runs above the plate and carries the thread that shows on the top side of the overlock. It picks up the loop from the lower looper and takes it to the needle.

12Lower looper

Also called: lower looper

It runs below the plate. It picks up the needle loop and carries the thread that shows on the underside. The loopers are to the overlocker what the hook is to the lockstitch machine: they form the stitch.

13Upper knife

Also called: moving knife

It moves up and down with each stitch and cuts the edge of the fabric against the lower knife, just before sewing. It can be disengaged when you don’t want to cut.

14Lower knife

Also called: fixed knife

The stationary knife, on the plate. Its position sets how much is trimmed off the edge. When the two knives don’t cut cleanly, the overlock comes out with loose threads.