Glossary

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This is a list of common terms and abbreviations used in the RepRap community.


ABS

Acrylonitrile Butadiene Styrene, a thermoplastic used as a 3D printer material. Often ABS is used as a short form, actually referring to filament made of ABS: 'Do you use ABS in your Mendel?' Be careful that sometimes filament sold as ABS is in fact mixed with other thermoplastic, thus altering its characteristics.

Bed

The build plate of the 3D printer on which parts are actually made.

Belt

Toothed gear belt, usually fiber-reinforced to prevent stretching. Used to transfer movement from the motors to other parts of a machine along with pulleys.

BOM

Bill of materials. A list of parts. There are BOMs for the whole Mendel and for individual components.

Also said to be "Book of Materials" in some contexts.

Carriage

The moving middle assembly on the x-axis of a RepRap which holds the extruder. Often referred to as: x-carriage.

Catalyst

A catalyst is a substance that speeds up a chemical reaction without being consumed itself in the reaction. A substance that alters (usually increases) the rate at which a reaction occurs.

Copolymers

Copolymers are additives that are included in the polymer blends with the intention to add certain properties to the main polymer.

All polymers have principal properties that are desired, but bring others that are not. A good example is Styrene, which is clear, has great accuracy when molded into a shape but is very brittle and ages poorly in sunlight. In certain commercial varnishes Butadyene can be added to give it some flexibility and UV protectors to make it more durable. The difference between copolymers and fillers is that the first ones participate in the chemical chain reaction and are bonded to the main monomer.

Curing

See: Hardening.

Endstop

RepRap's Cartesian axes all need a datum (also known as home position or end-stop) to reference their movements. At the start of each build each axis needs to back up until the datum point is reached. The switches also help protect the machine from moving past its intended range and damaging itself.

EVA

Ethylene Vinyl Acetate. Several early RepRap research experiments used off-the-shelf EVA glue sticks in hot-glue guns. Those glue sticks are mostly EVA which melts around 85°C.

Extrude

The act of placing the build material on the build platform, normally by heating thermoplastic to a liquid state and pushing it through a small nozzle commonly referred to as a "hot end".


Extruder

A group of parts which handles feeding and extruding of the build material. Consists of two assemblies: a cold end to pull and feed the thermoplastic from the spool, and a hot end that melts and extrudes the thermoplastic.

Filler

Fillers are solid materials that are added to polymers (or cements) and that do not interact chemically with it. They remain inert but do add special desired mechanical features to the compound. These can range from density alteration (make the compound heavier or lighter) additional strength (fibers...), resistance to abrasion and improved thermal properties (sands...) or simply thinning the compound to reduce material cost (talc).

FDM

Fused Deposition Modeling. The term fused deposition modeling and its abbreviation to FDM are trademarked by Stratasys Inc. The equivalent term fused filament fabrication (FFF), was coined by the members of the RepRap project to provide a phrase that would be legally unconstrained in its use.

FFF

Fused Filament Fabrication. Where a filament of one material (plastic, wax, metal, etc.) is deposited on top of or alongside the same (or similar) material making a joint (by heat or adhesion).

Filament

Two uses:

  • Plastic material made into (often 3 mm or 1.75mm) string to be used as raw material in 3D printers.
  • Extruded plastic (often < 1 mm).

Frog

Also known as the squashed frog, this is a part that the printing plate connects to. The frog connects directly to the linear bearings on the Y axis. The name comes from the original Sells Mendel part that looked like a "squashed frog".

G-code

The information sent over the wire from a PC to most computer numerical control (CNC) machines -- including most RepRaps -- is in G-code. While in principle a human could directly type G-code commands to a RepRap, most people prefer to use one of the many CAM Toolchains that reads a STL file and sends lines of G-code over the wire to the machine.

Some researchers are developing alternatives to G-code.

Hardening

The process by which the model hardens to its final form.

Heated Bed

A build surface warmed in order to keep the base of an extruded part from cooling (and shrinking) too quickly. Such shrinking leads to warping internal stresses in RP parts. The most common result is corners of parts lifting off the build surface. Heated beds usually yield higher quality finished builds. They commonly consist of glass, ceramics, or metal.

Heated Build Chamber

A heated build chamber is typically sealed and heated to prevent warping during the printing process.

HIPS

High Impact Polystyrene, a thermoplastic used as a 3D printing material. Similar to ABS in material properties and can be dissolved using limonene. HIPS is also BPA-free and less inflexible than either ABS or PLA.

Hot End

The heated nozzle portion of the extruder mechanism, which gets hot enough to melt plastic (or potentially other materials). Hot end parts use materials that withstand temperatures up to ~240 °C (and higher for newer all-metal designs). The diameter of available nozzle orifices ranges from about 0.15mm to 1.0mm, with sizes in the range 0.3mm-0.5mm currently being the most common.

Kapton Tape

Heat-resistant polyimide adhesive tape. Used to secure the heating element to the extruder barrel. It can also be used on the surface of a heated bed. It is compatible with a temperature range of about 269 C.

Monomer

A molecule that, under the correct conditions, can link together with others to form larger molecules called polymers. A monomer must be capable of forming two or more bonds to other monomers.

NEMA

Usually meant to refer to a specific size of stepper motor.

Nichrome

An alloy of nickel and chromium. Nichrome wire is used as a heating element in many extruder barrels and some heated bed designs. Simpler and less messy enamel resistors are often used for the same purpose.

Nylon

Nylon or polyamide is an engineering grade thermal plastic used in extruder based and laser sintering systems. There are different versions providing a range mechanical properties in either filament or powder form. These include nylon-6,6; nylon-6; nylon-6,9; nylon-6,10; nylon-6,12; nylon-11; nylon-12 and nylon-4,6.

OBJ

Short for Object File, is an alternative to the STL file format.

Oligomer

Oligomers are big molecules composed of monomer bricks, joined together in more or less branched fashion, so as to provide polymerization seeds for the final polymer. A free analogy would be that monomers are to oligomers what a water molecule is to a snowflake. In commercial resins, oligomers are mixed with their monomer components so as to achieve a polymer of desired properties, due to their ability to spatially organize the polymerization process.

Parametric

(Adjective) Adjustable in all dimensions. A parametric model is one that can be resized and or distorted to suit the user's needs. In CAD software, If a widget has a 1 cm hole in it, you can select that hole and make it a 5 mm hole with a few clicks, as opposed to a triangular mesh (see #STL), which is more difficult to adjust.

The native format of several [Useful Software Packages|useful software packages] can store parametric models.

PEEK

Polyether Ether Ketone. A high temperature thermoplastic used as a thermal barrier in the extruder.

PLA

Polylactic Acid. A biodegradable thermoplastic polymer used as a 3D printer material.

Often PLA is used as a short form, actually referring to filament made of PLA: I use PLA in my Mendel.

Photopolymer

Photopolymers are used in light reaction systems either with ultraviolet or visible energy. The liquid material is cross-linked or hardened when exposed to light. Photopolymers are used in both Digital Light Processing(DLP) and Stereolithography(SLA) systems.

PVA

Polyvinyl Alcohol, A water soluble filament used as 3D printing material. Often PVA is used as support material.

PTFE

Polytetrafluoroethylene (Teflon). A slippery thermoplastic often used as a barrel in the extruder to minimize friction with the filament.

Raft

A technique used to prevent warping. Parts are built on top of a 'raft' of disposable material instead of directly on the build surface. The raft is larger than the part and so has more adhesion. Rarely used with heated build surfaces.

RAMPS

RepRap Arduino Mega Pololu Shield - one of the more popular flavors of the "Official" electronics.

RepRap

A RepRap machine is a rapid prototyping machine that can manufacture a significant fraction of its own parts. The RepRap project is a quest to make a desktop-sized RepRap machine.

To reprap
v. To make something in a RepRap machine.
Reprappable
adj. Capable of being made in a RepRap machine.

See also: About

RepStrap

A 3D printing machine which can be used to make a RepRap, but is not a RepRap itself, as it wasn't made by something like itself. These are becoming less common as Mendel printed plastic parts become more available, but are still very popular. They're often sold in kit form or custom-made from scrounged parts.

See also: What Tooling Do You Have

RP

Rapid prototyping. Creating an object in a matter of hours on a "3D printer" as opposed to sending out a job to a modeling shop which may take days or weeks. Also known as additive manufacturing.

Setting

See: Hardening.

SLA

Stereo Lithography Apparatus. SLA is a registered trademark of 3D Systems Corporation. SL or stereolithography is commonly used in place of SLA.

SLS

Selective Laser Sintering. SLS is a registered trademark of 3D Systems Corporation. LS or laser sintering is commonly used in place of SLS.

Stepper motor

Motors which operate only in discrete increments of rotation. This is the type of motor most commonly used in Mendel, the earlier Darwin, and Repstraps.

STL

Short for Stereo Lithographic, which is a recommended file format used to describe 3D objects. A design program (e.g. AoI) can produce an STL file which can then be fed to a 3D printer or 3D rendering graphics package.

Possible alternatives to STL are discussed at a community specification for an improvement to STL files.

Support Material

Printed material that acts as support to allow overhangs, arches, etc. to be printed. Can either be a secondary material (PVA, HIPS) (requires dual extrusion) that can be removed, or the primary material that is broken away at the end of the print.

Squashed frog

See: Frog.

Thick Sheet

A firm flat sheet of material 4-6 mm thick used as a printing surface. A variety of materials have been used, but the most important property is that it must be flat.

Viscosity

Viscosity is a property of fluids determining it's resistance to flow. The higher the viscosity, the more difficult a material will be to extrude or dispense (more energy/pressure will be needed). Also, the higher the viscosity, the less the deposited thread of material will sag or change shape until hardening.

For a detailed definition see Viscosity on Wikipedia.

Vitamin

A non-replicated part.

In RepRap jargon, a "vitamin" is anything that you need to build a RepRap which cannot yet be printed on a RepRap. For example, bolts.

Wade's Extruder

One of many designs for the "cold end" of an extruder. It is based on Adrian's Geared Extruder, and includes many concepts from Nophead's Extruder Tweaks.