Garment Construction Techniques and Sewing Machinery
What the domain covers
This domain examines seams, stitches, sewing machine parts, adjustments, and industrial machinery. Expect practical questions on tension, stitch length, needle selection, seam types, and fault correction.
Core rules and concepts
- Stitch types include lockstitch, chainstitch, overlock, and coverstitch. Seam types include plain, French, flat-fell, and overlocked seams.
- Needle size and point type must suit fabric: sharp for wovens, ballpoint for knits, appropriate size for thread and fabric weight.
- Upper and bobbin tension should balance so the knot sits inside the fabric, not on the surface.
- Stitch length is measured in stitches per inch or millimetres; longer stitches suit basting, shorter stitches suit fine seams.
- Industrial machines are specialised: single-needle lockstitch, overlock, coverstitch, buttonhole, and bar-tack.
Worked example
A cotton knit T-shirt side seam skips stitches and the seam cracks when stretched. Reasoning: the needle may be a sharp point that cuts knit loops, and the stitch may be too short and non-stretch. Use a ballpoint needle of suitable size, a stretch or overlock stitch, and balanced tension. Test on a scrap of the same knit before sewing the garment.
Traps that cost marks
- Using a sharp needle on knits and causing holes.
- Fixing tension by changing only the bobbin case.
- Confusing overlock seaming with coverstitch hemming.
- Ignoring fabric weight when selecting thread and needle.
Exam focus
Diagnose faults by checking needle, thread, tension, stitch type, and fabric together.