Industrial Sewing Machines, Tools and Equipment
This domain tests industrial sewing machine types, parts, adjustments and maintenance.
Machine types
A single-needle lockstitch makes straight stitching and uses a bobbin thread. An overlock sews and trims edges and gives stretch. A flatlock or coverstitch folds and covers hems. A bartack reinforces stress points. Buttonhole and button-attach machines are specialised. The feed dog moves fabric, the presser foot holds it and the needle plate supports it.
Settings and care
Needle size must match fabric: a fine needle for voile, a heavier needle for denim. Stitches per inch and thread tension must balance. Maintenance includes cleaning lint, oiling as per the manual, checking timing and replacing blunt needles.
Worked example
A lockstitch machine skips stitches on polyester. Check in sequence: needle bent, blunt or wrong size; needle not fully inserted; thread not in the tension discs; hook timing; fabric pulled during sewing. Reasoning: a skipped stitch means the hook fails to pick up the needle loop, so needle, thread and timing are checked before changing the motor. Fit a new needle of the correct size and rethread.
Traps
Do not call an overlock a lockstitch; an overlock uses loopers, not a bobbin. Do not adjust tension randomly. Do not use a blunt needle because it still sews. Do not oil a machine without the manual. Do not ignore needle plate burrs.