3d Printing Terminology / Vocabulary

3d printing has a vocabulary all of its own and it’s pretty daunting for newcomers to pick up.  We’ve constructed this glossary of terms to help you out. 

This page was just launched so it will take some time for us to complete it.  If you have a question about a term that is not listed feel free to use the Contact Us form and ask.

 

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3d Printing

3d printing is a broad term used to describe any manufacturing process where a part is built up from nothing.  There are several different technologies that accomplish this with the most common being FFF/FDM and SLA.

A

ABS

Acrylonitrile Butadiene Styrene.  A common material used in FFF and FDM 3d printing.  See our 3d Printing Materials page for more details.

B

Build Plate

Certain 3d prints are created upon a flat surface.  In FFF and FDM printing the build plate is on the bottom surface of the print, but in resin-type printers, such as SLA, the build plate is at the top of the print.  The print proceeds through its defined layers with layer one being attached to the plate.

Build plates can be heated or unheated.  Heated build plates are required for any high temperature material, but optional for low temperature materials.  However materials will stick to the build plate better if it is heated in almost all circumstances.

Build plates will move in one dimension.  A build plate that moves in the X or Y directions is commonly referred to a “bedslinger” as the bed moves considerably during the the print.  A Prusa Mk3 is an example of a bedslinger.  Resin printers are examples of a printer that has a bed plate that moves only in the Z direction.

Common on low-end printers use a glass plate as they are cheap and flat, but many printers use a removable plate made of spring steel.  These are generally magnetically attached to the heat bed.  Removable build plates have the advantage of being flexible which allows for easy print removal.  Build plates have a build surface of some special material.

Build Surface

The build surface is the actual contact surface that the 3d print is built on.  The primary concern with build surfaces is adhesion.  Getting the first layer of a print to stick is critical to the success of the print overall.  Different materials are useful for getting different materials to stick.

Certain build plates, such as borosilicate glass, are often used without any special coating.  Removable build plates will often be coated with PEI which helps in the adhesion of the first layer of FFF and FDM prints.  Additionally certain tapes are often added to a build plate.  Blue painter’s tape was an early solution to first layer adhesion problems, and Kapton tape is still a favorite to enhance the adhesion of uncoated metal plates.

Additionally, some people will use adhesion modifiers such as glue stick or “ABS juice” to increase or even decrease bed adhesion.

C

CAD / CADD

CAD is an abbreviation for Computer Aided Design.  CADD adds “and drafting” to the end.

CAD is using a computer drafting software to create, modify, analyze and/or modify drawings or models.  These can be for 2d or 3d objects, and the result can be any number of a number of different file types including .STL, .OBJ, .3MF, .STP, .SLDPRT, .IPT, F3D, and many others.

D

Delamination

Delamination is when layers of a 3d print have not properly fused together and begin to split apart.  There are a number of factors that can contribute to delamination including incorrect extrusion temperature, cooling too rapidly during print, and under extrusion.  Whatever the reason, if one’s part delaminates it spells the end of the part’s useful life.

Dual Extrusion

An FDM 3d printer with dual extrusion capabilities has two extruders.  Each extruder is loaded with a separate spool of filament that can be identical or different.  Differences can include color variations, such as one black and one white, or material differences such as one ABS and the other TPU.

E

Extruder

 A 3d printer’s extruder is where the magic happens in an FFF/FDM printer.  This is s block of equipment that contains several critical parts including a stepper motor and a mechanism to grip the filament.  Generally the grip mechanism consists of one or more toothed gears but other setups exist.

There are two types of extruder: direct drive and Bowden.  A direct drive extruder sits directly above the hot end resulting is a short distance between the drive gears and where the liquid plastic is emitted.  In this setup, the extruder is part of the print head and generally moves in two of the X, Y, or Z axes, depending on the printer design.  For printing flexible filaments this is the architecture of choice.

Bowden extruders moves the extruder off the print head and somewhere onto the printer’s frame.  A guide tube then connects the extruder to the print head.  This results in lower mass that the machine needs to sling about as it is printing.  While the reduced mass of the printhead can enable faster and even higher quality printing, it comes with the issue of reduced retraction control which can lower print quality.  Additionally, Bowden rigs are poorly suited for printing any flexible filament.

F

FFF / FDM

These two terms are used interchangeably although there is nuance to their meaning.

FDM is the abbreviation for Fused Deposition Modeling.  This is a proprietary 3d printing technology developed and coined by Stratasys in 1989.

FFF is the abbreviation for Fused Filament Fabrication.  It was coined by the community of designers who developed open source 3d printing in order to avoid intellectual property claims from Stratasys.

Generally speaking, traditionally FDM machines use a heated build chamber, which results in better print quality, whereas FFF machines do not.  Many 3d printers are sold with a chamber and labeled as FFF today. (see this post for more details.)

Filament

A filament is a plastic fiber of a fixed diameter and material that is the input into an FFF or FDM 3d printer.  Filament is generally sold on spools that vary from 250 grams to 5 kilograms with 1 kg being the norm.

Filament is defined by its size, plastic type, and then any other factor that may be relevant.  An example would be 1.75 mm PLA in blue.

The two main diameters for filament are 1.75 and 2.85 mm.  2.85 is commonly referred to as 3 mm.  Higher quality filaments will adhere closer to the dimension indicated.  For instance, 1.75 +/- 0.5 mm is less precise than 1.75 +/- 0.2 mm, and will tend to produce lower quality prints due to small variations in the amount of plastic extruded.

While the original material availably to hobbyist was ABS plastic, there are now many options available for general use.  PLA is the most common choice due to its ease of use, but one can easily find PETG, ASA, Nylon, TPU, PC and many others.  It is important to select an appropriate material to one’s project as not every plastic is suited to every print.

The element is one of choice.  What color would you like to use?  Do you want sparkles?  Maybe glow in the dark?  Or perhaps even a wood-like finish?  There are hundreds of options that one can choose to make a 3d print truly unique.

G

Glass Transition Temperature

We think of plastics as being either solid or melted but there is a stage in between.  When a plastic is heated up beyond a certain temperature it begins to soften and lose its hardened shape.  That temperature is known as the glass transition temperature.  The material is still a solid but one can bend it with ease.

PLA plastic, the entry level plastic for most hobbyists, has a low glass transition temperature of between 50 and 80°C (122 to 175°F).  This means that a PLA print left in a car in summer can become soft and flexible and warp under its own weight.  In contrast ABS plastic, the material Legos are made from and a common 3d printing material, has a glass transition temperature of roughly 100°C (220°F).

H

Heat Break

A heat break is a device that separates components that need to operate at different temperatures.  In an FFF / FDM printer, a solid plastic filament is pushed into a heater block where it is melted and then extruded.  It is important that the filament does not melt too far before it is extruded as it will be difficult, if not impossible, to properly manage the amount extruded.  The heat break is made as small as possible and of a material that does not conduct heat well in order to try to keep as much heat as possible where it is needed, in the heater block.  The cool end of the heat break is often mated to a large heat sink to further alleviate heat creeping to where it is not wanted.

Heater Block

The heater block is the chassis that holds the hotend together.  These are commonly made from aluminum or copper and often have holes to accomodate the components that need to be brought together, but newer systems encapsulate the block.  Required are a heater and a some sort of device to measure the temperature such as thermocouple or thermistor in order to generate and manage the heat to melt the plastic.  The plastic will enter the block through a heat break and exit through a nozzle.  The heat break and nozzle meet surface to surface within the block establishing a single tube through which the plastic can move.

Heater Cartridge

A heater cartridge is a cylindrical heating element that is inserted into a hole of equivalent diameter.  It consists of a resistive coil that heats up when a current is passed through it.  The heat generated is then transferred to the metal sheath that surrounds the coil and from there to whatever encapsulates the cartridge.  For more information read this article on cartridge heaters.

Hotend

The hotend is where the magic happens in an FDM / FFF 3d printer.  It refers to the heated portion of the printhead, where the plastic filament is actually melted and extruded.  It consists of a heater block and nozzle, with the heater block consisting of a chassis (the heater block) that holds the nozzle, a heater, and an thermocouple.

I

Infill

Most 3d prints are neither a solid block of plastic nor a hollow shell.  Most prints have an internal structure that supports an outer shell that only fills a certain percentage of the empty space inside a shell.  That internal support structure is called infill.

The standard pattern for infill is simply a grid.  There are variations of the grid structure such as triangles or honeycombs which can have advantages in certain situations.  While this is good enough for most prints it is not equally strong in all orientations as it is a two dimensional structure, so there are three dimensional such as a network of tetrahedrons (three sided pyramids) that offer superior performance when needed.

Printing infill is a tradeoff between speed and strength.  A lot of infill takes longer to print and uses more material but generally results in a stronger part.  The typical starting point is 20%.

I

Infill

Most 3d prints are neither a solid block of plastic nor a hollow shell.  Most prints have an internal structure that supports an outer shell that only fills a certain percentage of the empty space inside a shell.  That internal support structure is called infill.

The standard pattern for infill is simply a grid.  There are variations of the grid structure such as triangles or honeycombs which can have advantages in certain situations.  While this is good enough for most prints it is not equally strong in all orientations as it is a two dimensional structure, so there are three dimensional such as a network of tetrahedrons (three sided pyramids) that offer superior performance when needed.

Printing infill is a tradeoff between speed and strength.  A lot of infill takes longer to print and uses more material but generally results in a stronger part.  The typical starting point is 20%.

L

Layer Height

3d printed models are made up of multiple thin layers of material stacked on on top of the other until the part is complete.  A standard layer height for FDM/FFF printers is 0.2 mm, whereas a standard layer height for SLA printers is 0.05 mm.  Layer height is sometimes refered to as print resolution, although this is not entirely correct.

M

Melting Point

The temperature at which a solid turns to liquid.  In 3d printing it is the minimum temperature at which one can set their extruder and get anything to come out.  However, trying to print at the absolute minimum temperature will not produce a good print.

N

Nozzle

In FDM/FFF printing, a plastic filament is melted and extruded through a nozzle.

Nozzles can be made of many different materials.  Generally one has to choose between good heat conductivity and good wear resistance.  A copper nozzle will conduct heat very well while a hardened steel nozzle will resist wear very well.  The standard material for nozzles is brass as these have a good combination of conductivity and wear resistance for common printing materials.  Nozzles are considered a consumable and will need to be replaced over the lifetime of a printer.

The second factor to consider with a nozzle is the size of the hole through which the plastic is extruded.  A smaller nozzle will enable a print with more detail while a larger nozzle will enable faster printing.  The default standard for desktop units is 0.4 mm, which provides a good combination of detail vs. printing speed.  Readily available sizes vary from 0.15 mm to 0.8 mm.

There are also choices if one wishes to use exotic nozzles.  Certain nozzles use a ruby at the orifice, which enables a good heat conductivity and good wear resistance.  There are additional materials such as tungsten carbide as well.  These can cost ten times that of more pedestrian nozzles and are only really needed for advanced materials or operations.

O

Object File (.OBJ)

A file format generated by 3d modeling programs.  It contains the geometry of the object with the coordinates of every vertex of it.  It does not, however, contain any information about scale so any user may have to make a judgement call on what units to apply to the object (inches vs. milimeters, for instance).

An OBJ file can be convereted by a “slicer” [program] into 3d printer machine readable code.  These are similar to STL files but contain more information.  They are commonly used in rendering programs but are fairly uncommon in the 3d printing world.

Overhang

A part of a 3d print where a newly printed layer of material has no layer below it, such as the arm of a person if it is sticking straight out.  Such unsupported layers are overhangs.

Generally FDM 3d printers can handle printing anything that is at or equal to 45 degrees from horizontal without any problem.  Anything less than that is considered an overhang.  In order for overhangs to print well it is usually necessary to use support as a scaffold to print upon.

The angle at which an overhand needs support varies from plastic to plastic and depends on the print temperature.  45 degrees is simply a rule of thumb as ABS can require support at a lower angle and PLA can have higher angles without needing support.

P

PLA

PLA stands for Polylactic Acid, which is a corn-based plastic commonly used in 3d printing.  It can be used in FDM/FFF printing and is widely available in both 1.75 and 3mm diameter filament.  Many people pitch PLA as a more environmentally friendly plastic due to it’s vegetable origins and abeing biodegradable.  This obscures the fact that the material is also quite useful as a plastic.  PLA is easy to print and the resulting parts are strong.  A major disadvantage of PLA is its low glass transition temperature.  At about 130 Fahrenheit the plastic loses it’s rigidity and will slump under its own weight.  While that temperature sounds high, it is easily achievable in a car left in the summer sun.  Overall PLA is an excellent material for 3d printing.

R

Resolution

The minimum detail size that can be reproduced.  It is important to note that on most 3d printers the best resolution is different in the X and Y vs. Z axes.

Most FDM 3d printers can manage a minimum of 0.1 mm layer height, but can manage 0.03 mm accuracy on the X and Y axes.  SLA printers have no issues down to 0.025 mm in layer height (and even smaller), but an X-Y resolution of 0.05 mm.  DLP printers have the interesting effect of being able to acxhieve better resolution on small prints than large prints on the same printer.

[edit] With the recent release of 8k SLA printers, it is now possible to achieve X-Y resolutions in the range of 0.022 mm (22 microns).  This incredible level of detail is actually smaller than what is visible to the naked eye.

S

Shell

The shell of a 3d printed object is it’s outer layers.

On FDM/FFF printers, for all sides excluding the top and bottom, the shell thickness will be defined by the number of perimeters and the thickness of those perimeters.  So the sides of a 3d printed object could be defined as “2 perimeters”.  The actual thickness of the shell is determined by the thickness of each perimeter, which is controlled in large part by the size of the nozzle.

The top and bottom of the shell are defined separately.  It is not uncommon to see a object with different numbers of shells in different locations.  For instance, 2 vertical shells, 6 top shells, and 4 bottom shells.  This has to do with how the machines create the object.  For instance, the top has more layers because it is important that it prints correctly and more layers may be necessary to cancel the effects of gravity when printing.

On SLA printers objects are often printed solid.  In this case the concept of a shell does not apply.  It is possible to hollow out these prints however, in which case one would define the desired shell thickness in millimeters.  However, in this case the shell thickness is often refered to as wall thickness.

T

Toolpath

To create an FDM 3d print the 3d printer’s controller moves the printhead about in a specified manner.  This motion, from the very start of a print through it’s completion is called the toolpath.

U

UV Light

UV light is ultraviolet light.  When 3d printing with resin as the base material, UV light can be used to cure the resin.  This is done in a two step process with the first step being the actual printing of the piece.  In this step the resin is cured solid but is not fully cured.  Once the piece has had any support removed, which is easier to do when the resin is not fully cured, and is otherwise inspected for quality it is placed into a device and bathed from all angles with UV light which fully cures the resin.

V

Volume

The amount of space occupied by a three dimentional object as measured in cubic units such as liters or quarts.  In 3d printing, subic centimeters or millimeters is generally used.

Volume is relevant in two aspects.  The first is the build volume of a particular printer.  This is calculated by multiplying the X, Y, ans Z build area dimensions together.  So a printer with dimensions X = 10 cm, Y = 20 cm, and Z = 30 cm the total build volumne would be 6,000 cubic centimeters.  Volume of 3d prints is generally measured in cubic millimeters .  This number is calculated automatically by the slicer software and is used to determine how much material will be used in the actual printing process.  It is possible for a 3d print with a small volume to not be printable on a printer with a larger print volume.  This would occur if any of the print’s dimensions exceed any of the printer’s build area dimensions regardless of the total volume.

X

X-Axis

The printable area of a 3d printer consists of 3 dimensions defined as X, Y, and Z.  The X-axis is generally considered to be the axis that runs side to side when standing in front of the printer.

Y

Y-Axis

The printable area of a 3d printer consists of 3 dimensions defined as X, Y, and Z.  The Y-axis is generally considered to be the axis that runs from front to back when standing in front of the printer.

Z

Z-Axis

The printable area of a 3d printer consists of 3 dimensions defined as X, Y, and Z.  The Z-axis is generally considered to be the axis that starts at the build plate and goes vertically upwards.

 

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