Glossary

Researched from published specifications and material data · Standard

Every definition is written to survive being quoted on its own.

Terms

Air assist Laser

Air assist is a stream of air directed at the cutting point. It clears smoke off the lens so the beam is not attenuated and blows debris out of the kerf, and on acrylic it is deliberately kept low because strong air frosts the polished edge.

Anodised aluminium Laser

Anodised aluminium is aluminium with a dyed oxide surface layer. A diode laser can bleach that dye to leave a permanent mark, which is marking rather than engraving, and a desktop CO2 will not mark bare aluminium without a coating.

Cast acrylic Laser

Cast acrylic is acrylic sheet made by casting rather than extrusion. It cuts with a polished edge and engraves white and frosty, which makes it the correct choice for laser work over extruded sheet.

CFM Both

Cubic feet per minute is a measure of airflow. Extraction for a laser is sized from the enclosure volume rather than the machine wattage, aiming to replace the air in the cabinet every six to ten seconds.

CO2 laser Laser

A CO2 laser is a cutter using a gas filled tube emitting at 10.6 um (far infrared). That far infrared wavelength is absorbed by clear acrylic and glass, which is the main reason to move up from a diode.

Convention Both

On this site, a convention is a widely used community rule of thumb that is useful and defensible but is not a specification, such as keeping layer height below three quarters of the nozzle diameter.

Depth of field Laser

Depth of field is the distance along the beam over which the spot stays close enough to its minimum size to work properly. It is often under a millimetre, which is why a bowed sheet loses focus mid cut.

Diode laser Laser

A diode laser is a desktop cutter using semiconductor laser diodes emitting at about 445 nm. It cuts wood, leather, card and dark acrylic, and it cannot cut clear acrylic at any power because the material is transparent at that wavelength.

Elephant foot 3D printing

Elephant foot is the outward bulge at the very bottom of a print, caused by the first layers being squashed while still soft on a hot bed. Lowering the bed temperature slightly after the first layer is the usual fix.

FDM 3D printing

Fused deposition modelling is 3D printing by melting a plastic filament and laying it down in layers. It is the most common desktop process and the one almost every benchtop printer uses.

Focal length Laser

Focal length is the distance from the lens at which the beam converges to its smallest spot. A shorter lens gives a finer spot over a shallower depth, which is why fine engraving and thick cutting want different lenses.

Honeycomb bed Laser

A honeycomb bed is a perforated panel that supports the workpiece while letting the beam and smoke pass through. It prevents back reflection scorching the underside of a cut.

Hotend 3D printing

The hotend is the assembly that melts filament and pushes it through the nozzle. A PTFE lined hotend is limited to roughly 240 C, while an all metal hotend can run hotter and handle polycarbonate and long ABS jobs.

Hygroscopic 3D printing

A hygroscopic material absorbs moisture from the surrounding air. Nylon does this faster than any other common filament, and wet filament pops, strings and prints noticeably weaker.

Infill 3D printing

Infill is the internal lattice that fills the inside of a printed part. Raising it adds material, weight, time and some strength, and dropping from 20 percent to 10 percent can cut filament use on a chunky part by around a quarter.

Kerf Laser

Kerf is the width of material removed by the laser beam, typically a fraction of a millimetre. It matters whenever cut parts must fit together, because every edge loses half a kerf width.

Layer height 3D printing

Layer height is the vertical thickness of each printed layer. It controls how smooth curved and sloping surfaces look, and the convention is to keep it between a quarter and three quarters of the nozzle diameter.

Line width 3D printing

Line width is the horizontal width of a single extruded bead, typically about 1.1 times the nozzle diameter. Together with layer height it sets the cross section of material the printer lays down.

MSLA 3D printing

Masked stereolithography is 3D printing by curing liquid photopolymer resin with an LCD masked ultraviolet light source. It produces far finer detail than FDM at the cost of a washing and curing workflow and real chemical handling.

Nozzle diameter 3D printing

Nozzle diameter is the size of the orifice the plastic is extruded through, commonly 0.2, 0.25, 0.4, 0.6, 0.8, 1 mm. It sets horizontal detail, which is why a smaller nozzle rather than a thinner layer is the fix for fine features in the XY plane.

Optical power Laser

Optical power is the actual laser output in watts, as distinct from the electrical draw or the marketing figure. A machine advertised as 80 W may deliver only 20 W of optical power, and a power percentage always refers to the optical figure.

Power density Laser

Power density is laser power per unit area at the workpiece, and it is what actually does the cutting. Halving the spot diameter quadruples the power density, which is why focus is the first thing to check when a machine stops cutting.

Purge tower 3D printing

A purge tower is a sacrificial block printed alongside a multi colour part so the nozzle can flush out the previous colour. On small multi colour prints the tower can use more filament than the part itself.

PVC Laser

Polyvinyl chloride is a plastic that must never be put in a laser. Cutting it releases chlorine gas, which forms hydrochloric acid, corrodes the machine from the inside and seriously harms the operator. Most cheap faux leather and sign vinyl is PVC.

Raster engraving Laser

Raster engraving is burning an image line by line, the way a printer lays down a page. Time scales directly with resolution, so doubling the DPI doubles the job.

Retraction 3D printing

Retraction is pulling filament back into the hotend during travel moves to relieve pressure. It is the main control for stringing, and too much of it causes clogs and gaps at the start of the next line.

Shrinkage 3D printing

Shrinkage is the contraction of a thermoplastic as it cools from melt temperature to room temperature. It runs from a few tenths of a percent in PLA to around two percent in nylon, and it is why a part that has to fit is modelled slightly oversized.

Skin sensitiser 3D printing

A skin sensitiser is a substance that can provoke a permanent allergic response after repeated contact. Uncured photopolymer resin is one, which is why nitrile gloves and ventilation are not optional in resin printing.

Standard Both

On this site, a standard is a published specification, a material property or a physical relationship that does not vary by opinion, such as a filament density or a laser wavelength.

Static pressure Both

Static pressure is the resistance a fan must overcome to move air through a duct. Flexible duct costs several times the static pressure of smooth rigid pipe, so a long flexible run quietly halves the airflow you paid for.

Transport velocity Both

Transport velocity is how fast air moves along a duct, in feet per minute. Between about 1000 and 2000 fpm keeps soot suspended without excessive noise; below that, particulate settles inside the run.

Vector cutting Laser

Vector cutting is following a path with the beam to cut through material, rather than scanning an area. Several fast passes usually beat one slow pass, because each pass clears the kerf so the beam reaches fresh material.

VOC Both

Volatile organic compounds are gases released by some materials when heated. ABS and ASA emit them along with ultrafine particles while printing, and an enclosure concentrates them rather than removing them.

Volumetric flow rate 3D printing

Volumetric flow rate is how much molten plastic a hotend can push out per second, measured in cubic millimetres per second. It equals layer height times line width times speed, and it is the real speed limit of a 3D printer.

Warping 3D printing

Warping is a printed part lifting away from the build plate as it cools and contracts. It is worst in ABS and ASA, and it is usually an environment problem caused by draughts or a cold room rather than a first layer problem.

Z offset 3D printing

Z offset is the fine adjustment of the nozzle height above the build plate. Measure a single printed layer with calipers, and the difference between the measured and requested thickness is exactly how far to move the nozzle.