Finishing / Safety

Break the corners before someone else does

A laser-cut blank is a set of knives. The 90° outside corner is the point of the knife. Put a radius on the outline, break the cut edge, and the part is safe to unpack, assemble, and install.

Design Guide / Edge Break9 minute read
Close-up of a laser-cut aluminum sheet-metal corner with a sharp knife edge
SHARP CORNER / KNIFE EDGE
CAD corner
≥ 0.5T, FLOOR 0.030″
Edge break
STANDARD ROUND
Primary reason
SAFETY
Do not model
THICKNESS CHAMFER
KNIFE
The laser-cut edge
Fiber cutting leaves a near-square 90° edge. Untreated, it behaves like a blade along every outline.
POINT
The 2D corner
A sharp outside corner in the DXF concentrates that blade into a needle. That is what catches skin and gloves.
0.5T
Minimum outline radius
Fillet outside corners to half thickness, never below 0.030″ on parts people handle.
R1
Default edge round
Standard Weber rounding, about 0.020–0.040″, is the handling-safe default on most gauges.
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01 / The Short Answer

Round the outline. Break the edge.

On any part a person will pick up, fillet the outside corners in CAD and order an edge break on the cut thickness. The first reason is safety. Coating wrap and a finished feel come along with it.

The laser does not leave a friendly edge. It leaves a square cut. If the outline also meets at 90°, you have designed a point. Gloves do not save you from that combination — they just delay the cut until the next person in the chain.

A part that ships with needle corners is a cut waiting on a hand.
Spec 01 / Outline
R ≥ 0.5T
Corner rounding in CAD

Fillet every outside corner people can grab. Floor at 0.030″. One times thickness is the comfortable default on panels, doors, and covers.

Spec 02 / Thickness
0.020–0.040″
Edge break on the cut

A standard round on the Hans Weber 1350 takes the knife off the top and bottom of the sheet. Do not model this as a chamfer on the edge face.

Design to this
BOTH
Handled parts need both

A radiused outline with a square knife edge still cuts. A broken edge with a needle corner still stabs. Specify both, or the leftover sharpness does the injury.

Default callout for a handled panel.Outside corners R 0.060″ or 1T, whichever is larger. Break all sharp edges, standard round. That covers 16 Ga. through 11 Ga. aluminum, mild steel, and stainless for unpacking and assembly. Use the table below when the gauge or the finish changes the number.
02 / Why It Cuts

The hazard is the point, not the burr.

People blame “the burr.” The burr is only half of it. A clean nitrogen-cut stainless edge with no dross is still a blade. A 90° outside corner turns that blade into something that finds skin.

Cuts happen in the places drawings never mention: the receiving dock, the kit cart, the assembler lining up the first PEM, the electrician fishing a panel into a rack. Product-facing covers and machine guards add the end user. A drawing that says nothing about edges is silently specifying a razor.

This is not a cosmetic preference dressed up as safety. A knife-edge panel will cut through a nitrile glove. Blood on a powder-coated cover is a rejected part and an injury report. Breaking the corner in CAD costs nothing. Leaving it sharp costs both.

If the part ships in a box, someone will grab a corner to lift it.That is the load case. Design the corner for a bare or gloved hand, not for the solid model looking crisp on screen.
03 / Two Different Sharpnesses

Do not swap the two specs.

Corner rounding lives in the flat pattern. Edge break lives on the cut thickness. They solve different cuts, and one does not replace the other.

TWO SPECSUSE BOTH ON HANDLED PARTS
CORNER
A fillet on the 2D outline. Removes the needle where two outer edges meet. Modeled in CAD. The laser cuts it.
In the DXF
EDGE
A small radius or equivalent chamfer on the 90° laser-cut thickness. Removes the knife along every outline, hole, and slot. Made on the Weber after cutting.
On the machine
Flat pattern with a sharp 90-degree outside corner and a square knife edge NEEDLE CORNER SQUARE KNIFE EDGE
✗ As-cut, sharp outline
The 90° corner is a point. The thickness is still 90°. Either one can cut. Together they will.
Flat pattern with a filleted outside corner and a broken edge R IN CAD BROKEN EDGE / STANDARD ROUND
✓ Radius + edge break
The outline fillet is cut by the laser. The edge round is applied on the Weber before bending. Both are in the process plan.

Internal corners are a different question. The laser already leaves a small radius in a notch, near half the kerf. You do not need a large fillet there for safety. Save the CAD radius for outside corners, tabs people pinch, and cover plates with exposed points.

04 / Recommended Sizes

By alloy family and thickness.

Use the picker for the gauge you are ordering, then read the two numbers: the outside-corner radius to model, and the edge-break class to order.

Recommended edge break & corner radius

Xeon NC handling-safe defaults
CAD outside corner
0.060″
Model this fillet on the outline
Edge break
0.020–0.040″
Standard round on the Weber
Class
R1
Handling-safe default

Outside-corner radius to model

Floor is 0.030″ on every handled part. Below that, the corner still feels like a point. Stainless at the thin end steps up because a nitrogen-cut, work-hardened edge stays sharper than aluminum of the same gauge.

ThicknessAluminumMild steelStainless
0.024–0.040″R 0.030″R 0.030″R 0.040″
0.048–0.075″R 0.040″R 0.040″R 0.060″
0.080–0.125″R 0.060″R 0.060″R 0.060″
0.135–0.188″R 0.090″R 0.090″R 0.090″
0.250″ and thickerR 0.125″R 0.125″R 0.125″

A compact rule if you do not want the table in your head: R ≥ max(0.030″, 0.5T). Use 1T on doors, covers, and anything an installer will carry by a corner.

Edge break on the cut thickness

These match the radius classes already published on the deburring guide. Thin stock gets a light pass so the Weber does not dish the sheet. Powder-coated or heavily handled plate steps up so coating wraps the edge.

ThicknessAluminumMild steelStainlessClass
Up to 0.040″0.008–0.015″0.010–0.020″0.010–0.020″Light break
0.048–0.125″0.020–0.040″0.020–0.040″0.020–0.040″Standard round
0.135″ and up0.030–0.060″0.040–0.080″0.030–0.060″Standard to heavy
Powder coat and anodize.Powder wants at least a standard round and an outside corner of R 0.030″ so the film does not pull off the edge. Type II anodize burns through a knife edge; break 0.010–0.020″ minimum before it goes in the tank. See the powder coating and Type II anodizing pages.
05 / How to Call It Out

Fillet the outline. Note the edge.

The laser cannot cut a chamfer through the thickness. If you model one on the edge face, DFM will strip it or flag it. Put the safety radius where the laser can actually cut it.

01
Fillet outside corners in the sheet-metal sketch or flat pattern.
That radius becomes a laser path. It is the only corner-rounding the cutter can produce. Apply it to every outside corner a hand can find, including tabs and cover-plate tips.
R ≥ MAX(0.030″, 0.5T)
02
Do not fillet or chamfer the thickness (edge) faces.
Those faces are the cut. A 45° chamfer modeled there is not a manufacturing instruction — it is geometry the laser will ignore. Order edge rounding, or add a note: Break all sharp edges, standard round.
NO EDGE-FACE CHAMFER
03
Keep holes and slots 2× the edge radius in from the outline.
A 1 mm edge round removes material at the perimeter. Features parked on the outline get nicked. The deburring design rules call for twice the specified edge radius of clearance.
04
Say so in the quote notes if the part is handled or cosmetic.
Standard finishing already knocks burrs down. If you need a defined handling-safe round, both-sides processing, or a heavy architectural radius, write it. Thin gauges under 0.024″ should be flagged so we drop pressure or hand-finish.
Leave a corner sharp only when it is a datum or a function.A locating notch, a shear blade, or a press-fit knife edge can stay pointed — call those features out so we do not round them off. Silence means we will treat every outside corner as a cut hazard.
06 / How We Break It

Weber first, then the brake.

Edge rounding runs on the Hans Weber 1350 while the part is still flat. Formed parts do not go through the brushes. Deburr, then bend. That sequence is already the shop default.

The machine combines a wide belt with multi-rotation brushes, 53″ wide. It takes the knife off the cut, rounds the edge to the class you ordered, and can lay a grain for powder or anodize. Parts smaller than about 2″ × 2″ need a carrier or a hand pass. Parts thinner than 0.020″ can dish under the head — that is why the thin-gauge row in the table is a light break.

If you only needed the burr gone, a light pass is enough for function. If a person will hold the part, order the standard round and put the CAD radius on the outline. The two operations are cheap compared with a cut.

Shop sequence
Cut → Round → Bend

The Weber only processes flats. Hardware, powder, and anodize come after forming. Details are on the metal finishing page.

Where to read the finish
Deburring tab

Every material page lists Weber capability for that alloy. Use this guide for the radius to ask for.

07 / Coating & Fatigue

Safety first. The edge also lasts longer.

The reason to design the break in is still a hand. Powder wrap, anodize integrity, and fatigue life are what you get for free once the knife is gone.

Powder pulls off a sharp edge. The film is thinnest at the corner, and that is where it chips in the field. A standard round plus R 0.030″ on the outline is the minimum that lets the coating turn the corner. Anodize has the same failure on a knife edge: the oxide thins, dyes burn through, and the corner looks raw.

A sharp corner is also a stress riser. On a cyclically loaded bracket the crack starts at the point you left in the DXF. Rounding the outline is fatigue insurance that costs a few extra millimeters of laser path.

08 / Release Checklist

Six lines before you upload.

If the part will be unpacked, assembled, or installed by a person, every box should already be true.

EDGE BREAK / RELEASE CHECK0 / 6 READY
Corners broken / quote next

Upload the file with the outline radii already in it.

Fillet the outside corners, pick the material and thickness, and note standard edge rounding if the part is handled or coated. We cut the radius and break the knife before the part is bent.

Upload your design →