The Hot-Wire Foam Cutting Wiki
Everything about hot-wire foam cutting — from your very first cut to building a 5-axis CNC machine. Beginner-friendly guides on foam materials, safety, G-code, hardware (ESP32, FluidNC, GRBL, PiBot, RAMPS), and every feature of the free cncfoam.com simulator. Use the search box or pick a topic below.
New to foam-cutter software? See how cncfoam.com compares to GMFC, DevFoam & JediCut, or browse the foam-cutting answers.
Getting Started
New to hot-wire foam cutting and cncfoam.com — the basics, your first cut and the key terms.
What is hot-wire foam cutting?A plain-English introduction to hot-wire foam cutting: how a heated wire slices through foam, …
What is cncfoam.com?
cncfoam.com is a free, browser-based hot-wire foam cutting simulator, community shape library …
Quick start: your first cut
A two-minute walkthrough: open cncfoam.com, load a shape, set your machine and foam size, pres…
Glossary of hot-wire & CNC terms
Definitions of the key hot-wire foam cutting and CNC terms used across cncfoam.com: kerf, feed…
Foam & the Science
How hot-wire cutting works, foam materials (EPS/XPS), wire temperature, kerf and safety.
How hot-wire cutting works (the physics)The physics of hot-wire foam cutting: resistive heating, why feedrate and temperature must be …
Foam materials guide (EPS, XPS, EPP & more)
Which foams can you hot-wire cut? A guide to EPS, XPS, EPP, PE, EVA and more — densities, melt…
Wire, temperature & feedrate
Choosing hot-wire material and diameter, setting temperature, and dialing in feedrate. How nic…
Kerf, corners & cut quality
What kerf is, why it matters for dimensional accuracy, how to compensate for it, and how to ge…
Safety & ventilation
Hot-wire foam cutting safety: fume extraction and ventilation, electrical safety with low-volt…
Using cncfoam.com
Every feature of the free browser tool — loading shapes, machine types, morphing, rotation and STL.
The cncfoam.com simulatorA tour of the cncfoam.com simulator: the 3D viewport, the status panel, the wire animation, th…
Loading shapes (SVG, DXF & G-code)
How to load shapes into cncfoam.com: single-part vs two-part morph, supported SVG/DXF/G-code f…
Machine types (2, 3, 4 & 5 axis)
Understand 2-axis, 3-axis, 4-axis and 5-axis hot-wire kinematics in cncfoam.com: what each can…
Material block & cutter envelope
Set your foam stock (material block) and machine reach (cutter envelope) in cncfoam.com, under…
Cut settings: material, feedrate & pre-heat
The Cut settings panel in cncfoam.com: pick a foam material to auto-suggest feedrate and pre-h…
The Object bar: scale, offset, rotate
Use the cncfoam.com Object bar to scale (per-axis or linked), offset and rotate the loaded sha…
Morphing & twisting two profiles
How 4/5-axis morph cuts work in cncfoam.com: blending a left and right profile into a ruled su…
Rotation axis & indexed cuts (3/5-axis)
How indexed rotation works on cncfoam.com: set up the A axis, position the foam on the axis, b…
What is a 5-axis foam cutter? (and why it is not what you think)
A 5-axis hot-wire foam cutter is really a 4-axis dual-tower machine (X,Y,U,V) plus an indexed …
The 3D solid cut preview (CSG)
How cncfoam.com shows the real finished part: solid foam stock minus the swept cut volume usin…
Viewers: G-code & side profiles
The floating G-code viewer and the X/Y and U/V block-side views in cncfoam.com: reading the co…
Transports: download, USB & Wi-Fi
Getting your cut to the machine from cncfoam.com: download G-code, stream over USB-serial (Web…
Accounts, projects & the shape library
Create a free cncfoam.com account to save named projects and sync settings, then browse, like,…
The GEN's shape generator
Generate cuttable foam shapes in cncfoam.com without CAD: NACA aerofoils and morphing wings, a…
The ambigram generator
Make a 3D foam ambigram that reads one word from the front and a different word from the side.…
The character generator
Cut loose letters, numbers, names and symbols as one continuous hot-wire outline. How cncfoam.…
The gear generator
Generate true involute gears in foam: spur gears (2-wire flat), plus helical and bevel gears v…
The wing generator
Generate foam RC wing panels from NACA 4-digit aerofoils: root + tip sections, taper, sweep an…
Ruled-surface architecture: wall panels & hypars
Why a straight hot wire can cut flowing wall panels and curved hyperbolic-paraboloid (hypar) s…
Screws, augers & the ruled-surface limit
Why a true shaft-and-thread screw can't be cut on a hot-wire machine, what you CAN make instea…
The helical flight generator (shaftless auger)
How a hot wire makes the spiral ribbon of an auger or Archimedes screw with no central shaft —…
The SVG cleaner
Why CAD-exported SVGs break parsers and how the cncfoam.com SVG cleaner fixes them: stripping …
Cutting 3D models (STL & OBJ)
How cncfoam.com turns an STL or OBJ 3D model into a hot-wire foam cut: the visual-hull / shape…
Rotating a part's starting position
Use the Rotate part buttons in the status panel to spin an imported STL/OBJ model 90° about th…
G-code
Reading and exporting hot-wire G-code: XYUVA axes, M-codes, profiles and FluidNC/GRBL output.
What is G-code?A beginner-friendly explanation of G-code: the plain-text language that tells CNC machines whe…
G-code for foam cutting
How hot-wire G-code differs from milling: M8/M9 hot-wire control, G4 pre-heat dwell, feedrate …
Axis names & your controller
Why hot-wire G-code uses X Y U V A, why some controllers (GRBL / FluidNC) want X Y Z B A inste…
Multi-axis & rotary G-code (U/V/A)
How 4-axis and 5-axis hot-wire G-code uses U and V for the second tower and A for the rotary a…
Hardware
Building and wiring the machine — controllers, ESP32/FluidNC, stepper drivers, wire and frame.
Choosing or building a machineHow to choose or build a CNC hot-wire foam cutter: frame tiers from DIY to pro, sizing your wo…
Controllers: FluidNC & GRBL
CNC controller firmware for hot-wire foam cutters: ESP32 + FluidNC (USB and Wi-Fi, YAML config…
PiBot, RAMPS & breakout boards
Controller hardware for hot-wire foam cutters: PiBot and RAMPS-style boards, multi-axis steppe…
Motors, drivers & motion
The motion system of a hot-wire foam cutter: NEMA-17 stepper motors, TMC2209 drivers, MGN line…
Hot-wire power & temperature control
Powering and controlling the hot wire: dedicated PSUs, switching with a MOSFET on a PWM output…
Wire temperature control (where it belongs)
Why hot-wire temperature is controlled on the machine, not in cncfoam.com: the tool emits only…
Wiring & first setup
Bringing a hot-wire CNC build to life: wiring motors and the hot-wire circuit, flashing firmwa…
Workflows & Tips
Practical end-to-end workflows and tips for cleaner, faster, more accurate foam cuts.
Designing wings & aerofoilsA workflow for cutting foam-core wings on cncfoam.com: choosing aerofoils, root-to-tip morph a…
Columns, ducts & lampshades
Project workflows beyond wings: square-to-round transition ducts, twisted and tapered columns,…
Troubleshooting common problems
Fixes for common hot-wire foam cutting problems: wire bowing, wide kerf, rounded corners, wire…
Tips for clean, accurate cuts
A checklist of practical hot-wire foam cutting tips: tensioning, test cuts on scrap, lead-ins,…
Reference
Quick reference: axis names, a glossary of terms and controller-specific notes.
Frequently asked questionsCommon questions about cncfoam.com and hot-wire foam cutting: is it free, do I need an account…
Keyboard shortcuts & controls
Mouse and keyboard controls for the cncfoam.com simulator: orbit, pan, zoom, play/pause, rewin…