Laser Cut Mild Steel

Choosing mild steel

Mild steel is low-carbon steel: strong, tough, easy to weld and easy to bend, and the metal itself costs less than stainless, aluminum, brass or copper. That makes it the default for brackets, plates, gussets, guards and frames, especially parts that will be welded into an assembly or painted afterward.

It's the wrong choice when a part has to stay bare outdoors, sit in water or stay light. Uncoated outdoor parts belong in galvanized steel or stainless, and parts where every ounce counts belong in aluminum.

Common steel parts and their thickness

Most mild steel work falls into a few families. Covers, guards, electrical box parts and light brackets come from thin sheet, which gets its stiffness from flanges folded in after cutting. Shelf brackets, mounting plates, tabs and trailer or equipment brackets use heavier sheet or light plate. Base plates, gussets and other structural parts are plate, at a thickness set by whoever designs the structure.

Thin steel is called out by gauge and plate by its fraction. The sheet metal gauge chart gives the decimal for every steel thickness in stock, so you can order the number your drawing means. Torn between two thicknesses? Price both in the quote. The example prices put one flat steel bracket beside the same bracket in a run of a hundred, so you can see how setup and quantity discounts change the price of each part.

For welded frames, keep the parts that meet at a joint reasonably close in thickness. Welding very thin sheet to heavy plate takes more care, because the heat needed to fuse the plate can burn through the sheet.

Designing for the laser

The laser cuts all the way through the sheet, so draw outlines, cutouts, holes and slots — not pockets or partial-depth holes. Keep holes at least about half the material thickness across so they cut cleanly; the quote flags anything smaller before you order.

Lines you set to engrave are etched on the surface instead of cut through — handy for part numbers, logos and bend or layout marks.

Designing steel parts to bolt, weld or bend

Draw bolt holes at clearance size for the fastener, and keep them well in from the edge on brackets that carry load — the metal between a hole and the edge is what stops it tearing out. The laser needs at least the material thickness there; a loaded part usually wants more, and structural connections should be checked by an engineer. Holes are cut, not tapped, so draw the tap-drill size for any hole you'll thread yourself. In thin sheet, where a thread has little to grip, a weld nut, rivet nut or self-clinching nut holds better than tapped threads.

Tab-and-slot joints let parts hold their own position while they're tacked. Size each slot from the mating tab's measured thickness plus a small allowance, and etch weld marks, centerlines or part numbers onto the parts so the welder can see what goes where. The laser file prep guide covers setting etch lines, and why the drawing shouldn't be offset for kerf.

For parts you'll bend, working out the flat pattern for your brake and tooling is up to you — the laser cuts the outline you draw. Add a bend relief, a small notch at least as wide as the metal is thick, wherever a bend line runs into an edge; keep holes a few thicknesses back from a bend so they don't stretch oval; and etch the bend lines so they're marked on the blank.

Rust, paint and powder coat in Las Vegas

Bare steel starts to rust wherever water sits on it. The valley's dry air slows that down, but monsoon storms, sprinkler overspray, swamp coolers and a damp garage floor all bring it on quickly, and rusting steel leaves orange streaks on the stucco or concrete below it. Indoors, a clear coat or a wipe of oil keeps parts bright; outdoors, plan paint or powder coat.

Powder coat is the usual finish for steel gates, brackets, furniture and screens. Tell the coater the parts are laser-cut mild steel, and whether any are hot-rolled plate with mill scale that has to come off first. Add a small hanging hole where it won't show, mark which faces are seen, and allow for the coating's thickness in slots, tabs and holes that have to fit, or ask the coater to mask them. A heavy coat can fill a light etch, so check before relying on etched marks under powder.

Outdoors, choose lighter colors for anything people touch: in a Las Vegas summer, a dark finish in direct sun can get hot enough to burn a hand. Screens, gate infill and wall panels are covered in more depth in the architectural metal guide.

What a mild steel order includes

Laser parts ship flat and as cut. The laser cuts the outline, holes and slots and etches any marks you set; bending, welding, tapping, deburring, and paint or powder coat are done after the parts leave the shop, by you, your fabricator or your finisher. To hand off a complete build — cut, bent, welded and coated — describe it in a custom fabrication inquiry. Tube, heavier plate and hardened tool steel go to other processes; the questions below say which.

How it's priced

Each part is priced on its cut length, each hole by its size, its pierces and any etched lines, plus setup and programming once per design, handling for each piece and loading for each sheet the job uses. Metal is billed by the area your parts use — each part's outer size plus a little cutting space — never more than the sheets they're cut from, and identical parts get automatic quantity discounts on the cutting.