The three design rules behind 90% of rejected DXFs

Tiny holes, features hugging the edge, and "sharp" inner corners — why the physics says no, and the one-line fixes that keep your quote from bouncing back.

NOTE NO. N-01

CATEGORY DESIGN FOR MFG

DRAWN BY NGUYỄN TRẦN TUẤN KHANG

DATE Jun 24, 2026

SCALE 1:1 · MM

READ 6 MIN

Laser-cut 3 mm mild steel parts with the problem spots circled in red marker

COVER — RED MARKUP ON 3 MM MILD STEEL, WAITING FOR FIXES

00 WHY FILES BOUNCE

Why files bounce

Last month we quoted 412 DXF files. Thirty-eight went back to their owners with red markup before a single sheet moved — and nearly all of them broke one of the same three rules.

None of this is style. It comes down to what a 0.2 mm beam of light physically does to molten metal. Learn the three rules once and your files go straight from inbox to nesting — which is how a 24-hour quote actually happens in 24 hours.

01 HOLE SIZE

Holes narrower than the sheet is thick

A laser doesn’t drill; it pierces, then orbits. For the melt to escape the kerf cleanly, the hole must be at least as wide as the material is thick. Below ⌀ 1 × t the beam re-melts its own edge on the way around — you get taper, dross on the underside, and a hole no bolt will thank you for.

SHEET t	MIN ⌀ — STEEL · O₂	MIN ⌀ — STAINLESS · N₂
1.5 mm	⌀ 1.5	⌀ 1.8
3 mm	⌀ 3.0	⌀ 3.6
6 mm	⌀ 6.0	⌀ 7.2
10 mm	⌀ 10.0	—

Over 8 mm stainless, talk to us first — gas choice depends on the edge you need.

Need smaller? Have us cut a centre mark and drill the hole in post — it’s nearly always cheaper than fighting the beam.

FIG. 01

Close-up — undersized hole with taper and dross — ⌀ 2 MM HOLE IN 6 MM PLATE: TAPER AND DROSS WHERE THE MELT HAD NOWHERE TO GO

02 EDGE DISTANCE

Features hugging the edge

Every cut dumps heat into the part. A hole that hugs the edge leaves a thin web of metal heated from both sides at once — it warps, discolours, or blows out entirely. The same goes for two features crowding each other.

If the geometry is non-negotiable — flanges, hinge knuckles — tell us. We can slow the feed and pulse the pierce, but that’s a decision for the quote, not a surprise for the machine.

“

The beam is a tool with a width. Design as if it exists, and it behaves as if it likes you.

03 INSIDE CORNERS

Zero-radius inside corners

CAD will happily draw an infinitely sharp inner corner; a beam with a 0.2 mm kerf cannot cut one. Forced into it, the machine decelerates to a stop, dwells, and burns a notch exactly where your part concentrates stress.

Outside corners are free — the beam simply travels past them. It’s only the inside ones that ask it to turn on a point.

04 BEFORE YOU EXPORT

Before you export

Three rules for geometry; five habits for the file itself. This is the exact list taped above the nesting PC:

01 Scale 1:1, in millimetres If a 100 mm edge measures 3.937, it came from inches. We catch most — not all.
02 Explode text and dimensions to curves Fonts don’t travel. Anything still "live" gets skipped by the nest.
03 Purge duplicate and overlapping lines Stacked lines cut twice: double heat, burned edge.
04 Close every contour Gaps under 0.01 mm still break the toolpath.
05 Material and thickness in the filename bracket_SS304_2.0.dxf answers three emails before they’re sent.

DRAWN BY NGUYỄN TRẦN TUẤN KHANG · DESIGN, CAD/CAM · CHECKED ON THE FLOOR

SHEET 2 · N-02 O₂ vs N₂: what assist gas does to your edge — and your invoice Jun 12, 2026 · 5 min read SHEET 3 · N-03 Bend radius cheat sheet: steel, stainless, aluminium May 28, 2026 · 7 min read SHEET 4 · N-04 Tolerances that cost money — and the ones that don’t May 15, 2026 · 6 min read

NEXT STEP

Not sure your file passes?

Send your DXF Cutting specs