Acrylonitrile Butadiene Styrene is 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. The melting temperature is 220-230°C, but can be different if the manufacturer has mixed this with other thermoplastics. ABS is soluble in acetone and can be use to smooth the surface of the print-out.


The build plate of the 3D printer on which parts are actually made. Typical materials are aluminium or glass.


Toothed gear belt, usually fiber-reinforced to prevent stretching (ex: GT2). Used to transfer movement from the motors to other parts of a machine along with pulleys.


Biopolymer has different meanings and is classified by Enders. Biopolymer can be made out of renewable, natural sources or petrol based, Biopolymer can be the polymers out of natural monomers (ex. PLA, bioFila) or Biopolymer can standard polymers but out of a natural source (ex. Polyamid. out or natural oils).


Computer Aided Design / Computer Aided Manufacturing. The use of 3D modelling software to aid the design testing and manufacture of parts.


Computer Aided Engineering.


Computer Numerical Control.


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


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 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.


See: Hardening.


Direct Digital Manufacturing


Digital Light Processing is a display device based on optical micro-electro-mechanical technology that uses a digital micromirror device. This technology is used in DLP front projectors, but also used in additive manufacturing as a power source in some printers to cure resins into solid 3D objects.


Direct Metal Deposition


Direct Metal Laser Sintering


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”.


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.


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).


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.


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).


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).


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. The electronics in the machine then translate these commands into motor controller operations, among other things.

Some researchers are developing alternatives to G-code.


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 finishing on the builds. They commonly consist of glass, ceramics, or metals like aluminum.

Heated Build Chamber

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


High Impact Polystyrene, a thermoplastic used as a 3D printing material. Similar to ABS in material properties and can be dissolved using limonene. Therefore the has to stay 24h in a limonene bath. HIPS is also BPA-free and less inflexible than either ABS or PLA. Melting point is 235°C and the heating plate should have 105-120°C.

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.


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.


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


(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.


Polycarbonate is a thermoplastic, it’s strong and impact resistant (It’s used in the making of bullet proof glass and compact discs) temperature resistant and it can be extruded (at the right temperature). It can be bent and formed while cold without cracking or deform and it is also very optically ‘crystal’ clear to visible light (opaque to UV light), but it’s actually not very easy to keep it clear during extrusion.


Polyethylene terephthalate, commonly abbreviated PET, PETE or PETP.A polymer used as a 3D material.


Polylactic Acid. A biodegradable thermoplastic polymer used as a 3D printer material. In many cases compounded with other polymers for become usable. Melding point 150-160°C. The material properties can vary, depending form the manufacture. It has been described as having a slightly sweet scent when melted or printing.


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.


Polyvinyl Alcohol is water soluble filament used as 3D printing material for support. It is generally used as one of the filaments in dual extrusion 3D printers. PVA is water soluble whereas ABS and PLA are non water soluble. So, the object printed using both PVA and PLA/ABS can be dipped in water for the support material to dissolve. Melting range for PVA is 200-230°C depending form the polymerization level.The PVA filament must be stored with a drying agent, since it will absorb moisture out of the air very easily. Also, PVA decomposes rapidly above 200°C as it can undergo pyrolysis at high temperatures, which may block your nozzle leading to extrusion difficulties. PVA is fully degradable and is a quick dissolver. To speed up dissolving, gentle stirring can be applied. Warm water also speeds up the dissolving process.


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


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


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.


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.

Support Material

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