3D printing glossary

The terms used in Dokimion reports and guides, defined in a sentence or two.

Additive manufacturing

Building a part layer by layer from a digital model. "3D printing" is the common name for it.

DfAM

Design for additive manufacturing: shaping a part around what the process can and cannot make, instead of copying a part designed for machining.

FDM

Fused deposition modelling, also called FFF. A nozzle melts plastic filament and lays it down layer by layer.

SLA

Stereolithography. Light cures liquid resin one layer at a time.

SLS

Selective laser sintering. A laser fuses nylon powder, and the surrounding powder supports the part.

LPBF

Laser powder bed fusion, also called SLM. A laser melts metal powder layer by layer.

Build plate

The surface the part is printed on.

Layer

One thin slice of the part, the unit the printer builds.

Orientation

How the part is rotated on the build plate. It changes support, height, surface quality and strength.

Overhang

A surface with nothing under it. Beyond a limit angle it needs support.

Bridge

A horizontal span supported only at its ends.

Support

A temporary structure printed under overhangs and removed afterwards.

Island

A feature that starts in mid-air: its first layer has no material under it.

Hanging point

The lowest point of a feature that points down, with nothing under it.

Down-facing surface

A surface that faces the build plate. It is usually rougher than the others.

Wall thickness

The distance between the two surfaces of a wall. Every technology has a smallest wall that can form.

Reliable wall

A wall thickness Dokimion treats as dependable for standard parameters. It is larger than the smallest wall and is a working assumption.

Drain hole

A hole in a hollow resin part that lets liquid resin out.

Powder escape hole

A hole in a closed cavity that lets loose powder out in SLS and metal printing.

Trapped powder

Powder that stays inside a closed cavity and cannot be removed.

Cross-section jump

A sudden change of the material area from one layer to the next. It changes the heat flow and can warp the part.

Compactness

The volume of the part divided by the volume of its convex hull. A low value means a branched part.

Warping

A part pulling away from its intended shape as it cools.

Anisotropy

A property that depends on direction. FDM parts are weaker across layers than along them.

Peel force

The force needed to separate a freshly cured resin layer from the film at the bottom of the vat.

Packing density

The share of the build volume filled by parts in SLS.

Slicer

Software that cuts a model into layers and prepares the print.

STL

A file format that stores a surface as triangles, without units or exact surfaces.

STEP

A CAD format that stores exact surfaces. Preferred when you have it.

3MF

A mesh format that, unlike STL, can carry units and more information.

Mesh

The surface of a part as a set of triangles.

Closed mesh

A mesh with no open edges. It encloses a volume, so the volume can be measured.

Open edge

An edge that belongs to only one triangle, a sign of a hole in the mesh.

Normal

The direction a triangle faces. In a correct mesh every normal points outward.

Kolesar Score

The rating Dokimion gives a part, from 0 to 100 and from A to E. See how it is built.

Last updated: 2026-10-26