Two boxes define your physical setup: the cutter envelope (what your machine can reach) and the material block (the foam you are cutting). Getting these right makes the simulation match reality.
The axis convention
cncfoam.com uses this machine convention:
- Z = left↔right — the spacing between the two towers (how far apart the wire ends are).
- Y = up↔down — vertical height.
- X = front↔back — depth on each tower plane.
Origin (0,0,0) sits at the bottom-left-front. By default X is reversed so the 0-line sits at the front, which matches how most people stand at the machine.
Cutter envelope (machine size)
In ⚙ Settings → Cutter size, set L→R (Z), Bottom→Top (Y) and Front→Back (X) to your machine's maximum travel. This draws the wireframe box and is used to warn you if a cut would exceed your machine's reach.
Material block (foam stock)
In the left panel under Material block, set the X/Y/Z size of your actual foam, plus X/Y/Z offset — where the block's corner sits relative to the 0-line. The block appears as a faint solid inside the envelope, and the solid cut preview is computed against it. Block size and offsets are saved per browser.
Fit warnings
cncfoam.com checks three things and shows a small banner if there is a problem:
- Part vs cutter envelope — the cut would exceed your machine's reach.
- Part vs material block — the cut overshoots the foam (on 2/4-axis; this is suppressed on 3/5-axis rotation, where cutting outside the block before rotating is normal).
- Material vs machine — your foam is close to (≥95%) or larger than the machine envelope.
Centering on the rotation axis
On 3/5-axis machines, a Center on rot. axis button moves the block so its centre sits on the rotation axis, so the foam spins in place. See Rotation axis & indexed cuts.