Cutting, Shaping, Joining and Assembly Techniques
This domain tests whether you can cut, shape and join waste materials accurately enough for the piece to hold together and look deliberate.
Cutting
- Paper and thin card: scissors or knife on a mat, always against a steel ruler.
- Cardboard: utility knife, three to four light passes, blade changed when it starts dragging.
- Plastic bottles: pierce a start hole with an awl, then use scissors; never a knife on curved plastic.
- Metal: tin snips for sheet, hacksaw with an 18–24 TPI blade for rod and pipe, then file every edge.
- Wire: cutting pliers, never scissors.
Cut 1–2 mm outside the line and sand back to it - material cannot be added back.
Shaping
Score fold lines with a blunt awl so folds are crisp and straight. Bend corrugated board along the flutes for curved work. Soften bottle plastic in water at 70–80 °C in a ventilated area and shape it wearing gloves.
Joining
- PVA for paper, board and wood; hot glue for quick tacking of plastic; epoxy for metal and glass; contact adhesive for laminates.
- Mechanical joints carry load better than glue: slot-and-notch in cardboard, lap joints, stitching, wire wrapping, rivets, nuts and bolts.
- Always dry-fit, mark, then glue, clamp and cure fully - usually 24 hours for PVA.
Worked example
A cardboard shelf must carry 2 kg. Cut slots to material thickness plus 0.2 mm clearance, half-depth in the shelf and half in the upright, dry-fit, glue the slot faces, clamp and cure. Reasoning: glue alone fails in peel; the slot converts load into shear and compression, which cardboard handles well.
Traps
Flooding a joint with glue, which slows drying and squeezes out; hot glue onto wet paint; cutting towards your own hand; slots cut too loose; assembling before finishing surfaces you can no longer reach.