// Glossary

Laser & 3D printing terms, explained

The words you’ll meet in manuals, forums and spec sheets — kerf, focus, DPI, LPI, slicers, layer height and the rest — in plain English.

LasersAir assist: A jet of compressed air aimed at the point where the laser meets the material. It blows smoke and debris out of the cut, which helps reduce flare-ups and scorching and usually gives cleaner cut edges. Some machines have it built in; on others it is an add-on pump. See also: Kerf, Honeycomb bed.
3D printingAuto bed levelling: A 3D printer feature where the printer probes the build plate at several points and adjusts for any unevenness, so the first layer goes down evenly. It saves manual levelling with paper and knobs. See also: First layer, Build plate.
3D printingBed slinger: Informal name for a 3D printer whose build plate moves back and forth along one axis (Y) while the print head moves side to side and up. Simple and open, but the moving bed limits how fast tall parts can be printed. See also: CoreXY.
3D printingBrim: A thin, flat border printed around the base of a part on the first layer. It increases contact with the build plate to help stop corners lifting, and is trimmed off afterwards. See also: Warping, Raft.
3D printingBuild plate: The surface a 3D print is built on. Many modern printers use removable spring-steel sheets coated with PEI or a textured finish: you flex the sheet to pop the finished print off. Keep it free of finger grease — wiping with isopropyl alcohol is common practice. See also: First layer, Auto bed levelling.
LasersCO2 laser: A laser that uses a gas-filled tube to produce infrared light at about 10.6 micrometres (10,600nm). CO2 lasers cut and engrave wood, card, leather and acrylic — including clear acrylic — and engrave glass and stone. They don’t mark bare metal on their own. See also: Diode laser, Fibre laser, Wavelength.
3D printingCoreXY: A 3D printer motion system in which two motors work together through crossed belts to move the print head in X and Y, while the bed only moves down as layers build up. It allows high speeds and suits enclosed, box-shaped printers. See also: Bed slinger.
LasersDiode laser: A laser built from semiconductor diodes, usually emitting visible blue light around 450–455nm. Diode lasers are compact and simple, engrave a wide range of materials and cut thin wood, card and dark opaque acrylic. Blue light passes through clear and blue acrylic, so diode lasers can’t cut those. See also: CO2 laser, Wavelength, Laser class.
LasersDithering: Turning a greyscale photo into a pattern of dots or lines so a laser — which can only burn or not burn at each point — can reproduce shades of grey. Laser software offers several dithering methods; the best one depends on the image and material. See also: DPI, Raster engraving.
LasersDPI: Dots per inch: how finely a raster engraving is divided along each scan line. Higher DPI gives more detail but takes longer and can over-burn some materials. See also: LPI, Raster engraving.
Design & filesDXF: A widely used vector file format from CAD software. Most laser software can import DXF files for cutting paths. See also: SVG, Vector.
3D printingElephant’s foot: A 3D printing flaw where the first few layers bulge outwards because they were squashed onto the bed or stayed soft from bed heat. It makes the bottom of a part slightly wider than designed. See also: First layer.
3D printingExposure time: In resin printing, how long each layer is exposed to UV light. Too short and layers don’t cure or stick; too long and fine detail fills in. Resin makers usually give starting values for each printer. See also: MSLA, Post-curing.
3D printingFEP film: The clear non-stick film that forms the bottom of a resin printer’s vat. UV light passes through it to cure each layer; it is a wear part and must be kept free of scratches and cured debris. See also: MSLA.
LasersFibre laser: An infrared laser (typically 1064nm) generated in an optical fibre. Fibre lasers mark and engrave metals and many plastics; desktop versions usually use a galvo head and a small marking field rather than cutting sheet material. See also: Galvo, CO2 laser, Diode laser.
Design & filesFinger joint: Also called a box joint: interlocking rectangular tabs cut into the edges of two panels so they slot together at a right angle. Laser-cut boxes use them because they are strong and easy to design. Allow for kerf so the tabs fit snugly. See also: Kerf, Living hinge.
3D printingFirst layer: The first layer of a 3D print, laid directly onto the build plate. If it is too high the print won’t stick; too low and it is squashed. Most print failures start here. See also: Auto bed levelling, Build plate, Brim.
LasersFocal length: The distance from the laser’s lens to the point where the beam comes to focus. Short focal-length lenses give a finer spot for detailed engraving; longer ones keep the beam narrow through thicker material. See also: Focus.
LasersFocus: The point where the laser beam is narrowest and most concentrated. A correctly focused beam gives the thinnest kerf and the sharpest engraving. Machines focus with a manual gauge, a motorised Z axis or automatic focusing — and the focus must suit the material’s thickness. See also: Kerf, Focal length.
3D printingG-code: The plain-text list of machine instructions (move here, heat to this, extrude that much) that a slicer produces and a 3D printer — or a GRBL-based laser — follows. See also: Slicer.
LasersGalvo: A laser head that steers the beam with fast-moving mirrors (galvanometers) instead of moving the head on rails. Galvo machines mark very quickly but over a small area; they are common on fibre markers. See also: Gantry, Fibre laser.
LasersGantry: A laser (or CNC) layout where the head moves on X and Y rails over the bed. Gantries give large work areas; most diode engravers and desktop CO2 cutters use one. See also: Galvo.
LasersHoneycomb bed: An aluminium grid with hexagonal cells that supports material on a laser bed. It lets smoke escape underneath and reduces the scorch marks that a solid bed reflects back onto the underside of a cut. See also: Air assist.
3D printingHygroscopic: Absorbs moisture from the air. Many filaments — nylon, TPU and PETG in particular — print badly when damp (stringing, popping, weak layers), so they are stored sealed and dried before use. See also: Stringing.
3D printingInfill: The internal structure a slicer prints inside a solid-looking part, set as a percentage and a pattern. More infill means stronger, heavier parts that take longer to print. See also: Walls, Slicer.
LasersInterlock: A safety switch that stops the laser firing when a lid or door is opened. Interlocks are part of what lets an enclosed machine be classed as Class 1. See also: Laser class.
LasersKerf: The width of material the laser burns away as it cuts — usually a fraction of a millimetre. It depends on the material, focus and power. Designs with tight-fitting joints add a small offset to allow for it. See also: Focus, Finger joint.
LasersLaser class: The hazard classification of a laser product under the international standard IEC 60825-1 (BS EN 60825-1 in the UK), from Class 1 to Class 4. An enclosed machine can be Class 1 even though the laser inside is Class 4, because the enclosure and interlocks keep the beam in. Open-frame engravers expose a Class 4 beam. See our safety guide. See also: Optical density, Interlock.
3D printingLayer height: The thickness of each layer of a 3D print. Thinner layers show fewer steps on curves and finer detail but take longer; thicker layers print faster and are often stronger. See also: Slicer, Nozzle.
Design & filesLiving hinge: A pattern of closely spaced cuts that lets a rigid sheet — usually plywood or MDF — bend. Lasers make it easy to cut curved box sides and flexible covers this way. See also: Finger joint, Kerf.
LasersLPI: Lines per inch: how many scan lines a raster engraving uses per inch of height. Some software sets this as a line interval in millimetres instead. More lines give smoother fills but take longer. See also: DPI, Raster engraving.
LasersMasking: Paper tape (or the maker’s protective film) applied to a sheet before cutting or engraving to protect the surface from smoke staining. Peel it off after the job. See also: Air assist.
LasersMaterial test grid: A grid of small squares or lines, each burned with a different combination of power and speed, used to find the right settings for a new material. Most laser software can generate one. See also: Kerf, Focus.
3D printingMSLA: Masked stereolithography: a resin 3D printing method where UV light shines through an LCD screen that acts as a mask, curing a whole layer of liquid resin at once. Most desktop resin printers use it. See also: Exposure time, FEP film, Post-curing.
3D printingMulti-material unit: An add-on or built-in system that feeds several filaments to one printer and swaps between them automatically, for multi-colour or multi-material prints. Brands give them their own names, such as Bambu Lab’s AMS or Prusa’s MMU. See also: Slicer.
Design & filesNesting: Arranging parts close together on a sheet to waste as little material as possible. Some laser software can do it automatically. See also: Kerf.
3D printingNozzle: The small brass or steel tip that melted filament comes out of. 0.4mm is the usual standard; smaller nozzles give finer detail, larger ones print faster. Abrasive filaments (such as carbon-fibre filled) need a hardened nozzle. See also: Layer height.
LasersOptical density: OD: how strongly laser safety eyewear blocks a particular wavelength, on a logarithmic scale — OD 4 lets through one ten-thousandth of the light. Eyewear must be rated for your laser’s wavelength; a high OD at the wrong wavelength gives no protection. See also: Wavelength, Laser class.
LasersPassthrough: A slot in the front and back of an enclosed laser that lets material longer than the bed slide through, so long pieces can be worked in sections. See also: Laser class.
3D printingPost-curing: Exposing a washed resin print to more UV light so it reaches its full hardness. Wash-and-cure stations combine both steps. See also: MSLA.
3D printingRaft: A disposable platform of several layers printed under a part to help it stick and to even out an uneven bed. Less common now that most printers level automatically. See also: Brim.
LasersRaster engraving: Engraving by scanning back and forth line by line, firing the laser to build up an image or filled area — like an inkjet printer. Good for photos, text fills and shading. See also: Vector, DPI, LPI.
3D printingRetraction: Pulling the filament back slightly when the print head moves between areas, so molten plastic doesn’t ooze and leave strings. See also: Stringing.
LasersRotary attachment: An accessory that turns round objects — tumblers, bottles, rolling pins — under the laser so you can engrave all the way around them. Machines support specific rotary models. See also: Raster engraving.
3D printingSlicer: Software that turns a 3D model (STL, 3MF and so on) into the layer-by-layer instructions a 3D printer follows, with settings for layer height, walls, infill, supports and speed. See also: G-code, Infill, Supports.
3D printingStringing: Fine wisps of plastic left between parts of a print when the nozzle oozes while travelling. Usually fixed with retraction settings, a lower temperature or drier filament. See also: Retraction, Hygroscopic.
3D printingSupports: Temporary structures a slicer adds under overhangs and bridges so they don’t print in mid-air. They are snapped or cut off afterwards. See also: Slicer.
Design & filesSVG: Scalable Vector Graphics: an open vector file format that most design and laser software can read. Shapes stay sharp at any size, which suits cutting paths. See also: DXF, Vector.
Design & filesVector: Artwork made of paths and shapes rather than pixels. Lasers follow vector paths to cut or score lines; images made of pixels (raster images) are engraved by scanning instead. See also: Raster engraving, SVG.
3D printingWalls: Also called perimeters: the outlines a slicer prints around each layer. More walls usually add more strength than more infill. See also: Infill.
3D printingWarping: Corners of a print lifting off the build plate as the plastic cools and shrinks. ABS and ASA are prone to it; an enclosure, a brim and a clean plate help. See also: Brim, Build plate.
LasersWavelength: The ‘colour’ of the laser light, which decides which materials absorb it. Blue diode lasers emit around 450–455nm, fibre lasers 1064nm and CO2 lasers about 10,600nm. Safety eyewear must be rated for the specific wavelength. See also: Diode laser, CO2 laser, Fibre laser, Optical density.