Hot-wire foam cutting answers

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Category Materials / foams · 20 matches. Clear filters.

• EPS vs XPS vs EPP vs EPO — which foam for what?
  EPS (expanded polystyrene, white bead foam) is cheap, light and easy to cut — great for big parts, cores, masters and packaging; its bead structure leaves a slightly coar…
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• Can I hot-wire cut polyurethane (PU) foam?
  Not well. Polyurethane does not cleanly melt-cut the way polystyrene does — instead of slicing, a hot wire tends to char, gum and smoke, leaving a rough, sticky edge and…
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• Can I cut foam board, Depron or fan-fold?
  Yes — thin sheet foams like Depron, fan-fold (FFF) and thin XPS hot-wire nicely for flat-plate RC models and prototypes, but they are usually so thin that a straightedge…
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• What foam density is best for RC wings?
  For most RC wing cores, lower-density EPS around 20–30 kg/m³ is the common choice: light, easy to cut, and stiff enough once sheeted with veneer, fibreglass or tape. For…
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• Is it safe to cut polystyrene indoors?
  With ventilation, generally yes for EPS/XPS at a correct low temperature, but never in a sealed room. The cut releases styrene vapour and fine particulates that are irrit…
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• Why does my foam have a hard skin, and how do I handle it?
  Extruded foams (XPS) and moulded blocks often have a denser skin on the outer faces from manufacturing. It can cut slightly differently from the softer core — sometimes n…
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• Can I glue, finish or fibreglass a hot-wire cut?
  Yes, and that is the normal next step — the foam core gives shape, the finish gives strength. Use foam-safe products: epoxy is fine, polyurethane glues and white/PVA work…
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• Where can I buy large foam blocks affordably?
  For XPS, the cheapest source is usually building-insulation board from a builders' merchant or DIY store (the pink/blue/green sheets) — laminate sheets with foam-safe glu…
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• How do I finish / paint cut foam?
  Two paths: Quick: light sand with 220-grit paper to even out the melt surface, then prime with FOAM-SAFE primer (water-based latex, or Plasti-Dip, or Plastikote Foam Coat…
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• What kinds of foam can I cut with a hot wire?
  Thermoplastic foams that melt cleanly: - EPS (expanded polystyrene): the white "packaging" foam. Cheap. Cuts beautifully. - XPS (extruded polystyrene): pink/blue insulati…
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• Is the bead pattern on EPS hiding under XPS as well?
  No. XPS is EXTRUDED (one big mass squeezed through a die), so there's no bead structure — it's homogeneous. Cut surface is smooth + uniform. That's why architectural mode…
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• What about cutting wax for casting / sculpture?
  Yes — paraffin wax and microcrystalline wax both melt cleanly with a hot wire. Lower temp than EPS (wax melts around 60-80°C vs styrene's softening at 100°C, but wax is m…
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• Why does my EPP cut keep being bouncy and dragging the wire?
  EPP is rubbery + has memory. The wire pushes into the foam, foam compresses, foam springs back behind the wire and grabs it. You'll see the wire bowing forward as it cuts…
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• Can I cut Depron / fanfold / dollar-tree foam with a hot wire?
  Yes, but it's overkill. Depron and similar sheet foams are thin (3-6mm) and easier to cut with a sharp knife and a steel ruler. The hot-wire shines on THICK blocks where…
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• What density EPS for RC plane wings?
  18-25 kg/m³ is the sweet spot. Below that the foam crushes too easily; above that it's needlessly heavy for the strength you get. For specific applications: - Park flyer…
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• Where do you buy big foam blocks in Europe / US?
  Europe: - Builders' merchants (Hornbach, Bauhaus, Praxis, Brico Dépôt) for XPS insulation panels - Local packaging suppliers for EPS — search "EPS blok" / "Styropor block…
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• EPS vs XPS — which should I use for what?
  EPS if you need: - Cheap (€8-15/m³) - Large blocks (easy to find 500x500x1000 at any builders' merchant) - Lightweight final parts - You can live with the visible "bead"…
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• Does foam shrink over time after cutting?
  Negligibly for EPS / XPS — these are stable at room temperature. Long-term UV exposure makes EPS yellow + brittle over years; XPS holds up better. EPP and PE can take a p…
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• Can I glue foam parts together? With what?
  Yes: - Hot-melt glue — fast, strong, slightly melts the foam (good for fillets) - Polyurethane construction adhesive (Gorilla Glue, Soudal Fix All) — strong, foams up to…
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• Hot wire vs hot knife vs CNC router for foam — which when?
  Hot wire (this tool): best for prismatic / lofted shapes — wings, columns, signs, moulds. Fast, almost no waste, no dust, cuts thick blocks easily. Limited to ruled surfa…
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