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3D Printing at the Library of Engineering and Science

Inspiration

Thank you to the Lyndhurst Girls' STEM Club for suggesting the addition of a glossary! 

If you have additions or edits for this guide, please let us know at walc3dpr@purdue.edu

Glossary

ABS:

Acrylonitrile Butadiene Styrene, a type of plastic filament.  ABS was a popular material to print with because of its heat resistance (100°C/ 212°F) and the ease of finishing completed prints with acetone.  ABS has generally fallen out of favor as it can be a temperamental filament to print with, can warp in UV light, and produces more VOCs than PLA.  The library does not print with ABS.

Acetone:

a.k.a. nail polish remover.  Acetone can be used to smooth the print lines of ABS prints.  Acetone does not react to PLA and we do not use it at the library.

ASA:

Acrylic Styrene Acrylonitrile, a type of plastic filament.  ASA is very similar to ABS in terms of strength and heat tolerance, but does not react to UV light, making it the preferred filament for outdoor use.  ASA also contains styrene, so VOCs are a concern.

Brim:

A single layer 8mm ring of filament which can assist in securing a print to the build plate.  8mm is the default in Cura, but this diameter can be changed.  Used for objects with smaller bases than tops, or objects with small supports that might come off the build plate without additional adhesion.  "If you liked it then you should have put a brim on it" is line from the popular 3D print song, Single Layers.

Build Plate/Print Bed:

The surface on which a FDM 3D print begins.  The dimensions of the build plate will be one factor in determining the size of a possible print.  Build plates are typically made of glass or PEI, though there are other materials available.

CAD:

Computer-Aided Design.  CAD software is used to create 3D designs for 3D printing and a variety of other applications (architecture, room design, carpentry, engineering, artwork, etc.).

Extruder:

The gears/mechanism that pushes filament out of the hot end on a FDM 3D printer.  Can be used in the sentence "the filament is stuck in the !#$@ extruder and now we have to take the entire print head apart".

FDM:

Fused Deposition Modeling.  The catchall term for any 3D printing that layers material extruded through a nozzle to build a print.

Filament:

The material used to print on FDM printers.  Filament is generally some sort of plastic and can be purchased on a spool.  PLA, ABS and nylon are the most popular commercial materials.  Specialty filament might include metal, wood or even coffee.

Flow:

The rate at which filament is extruded from the hot end.  This can be adjusted to resolve print issue like filament gaps (increase flow), or over extrusion (reduce flow).

G-Code:

The code generated by a slicing software with instructions for a 3D printer.  This code tells the printer what settings to use (heat, speed, layer height, etc.) and how to move the nozzle along the X, Y and Z-axes to create a 3D object.

Horizontal Expansion:

A helpful setting that can be adjusted in your slicing software. If parts of an object show up when viewing a in solid mode, but disappear in layer mode, they may be too detailed to print with your printer.  Horizontal expansion expands a print fractionally along the X and Y-axes.  Generally is not wise to increase horizontal expansion above .2mm, as the details of a print will be lost.  Between .05 -0.1mm is the preferred adjustment.

Hot End:

The part of an FDM printer that gets hot.  This includes the nozzle, heat sink and any additional metal pieces near the nozzle.

Infill:

The material inside a print.  Infill can be reduced or increased depending on the object's use.  100% infill will produce a solid object.  10% infill is almost hollow.  Below 10% there can be issues with structural integrity.

Layer Height:

The diameter of filament extruded each layer of an FDM print.  A lower layer height (e.g. 0.14mm) will generally produce a more detailed print, whereas a higher layer height (e.g. 0.3mm) will print more quickly and works well for larger objects.  Our printers can go down to about .02mm, but it not generally advisable.

PEI:

Polyetherimide, considered one of the better materials for FMD print beds.  A PEI sheet offers good adhesion for PLA, ABS and nylon prints.

PETG:

Polyethylene Terephthalate Glycol, a somewhat clear and durable co-polyester filament, with fewer VOCs than ABS.  Prints at a high temperature and can be subject to warping.

PLA:

Polylactic Acid, a type of plastic often used for FDM 3D printing.  PLA is derived from corn, and is technically biodegradable, but it can take centuries to decompose if specific environmental needs are not met.  This is currently the preferred filament of the Libraries because of its ease, consistency, and low VOCs emissions.  PLA is not as heat resistant as ABS or as strong as PETG.

Outer Wall Wipe Distance:

As FDM printers move between layers on a print, they retract filament slightly.  Adjusting the outer wall wipe distance changes the distance between layers the nozzle moves before it resumes extrusion.  This setting can be changed if you are experiencing a noticeable seam on the Z-axis of your print.  Increasing the number will make the gap larger, decreasing should make it smaller.  Generally the desirable range is between 0.2 - 0.4.

Raft:

Layers of filament printed before the object print begins.  Small pieces often adhere better to a raft than a print bed.

Resin:

SLA printing uses liquid resin and a UV laser beam to print 3D objects.  This method of printing can produce very smooth prints with minimal supports.  Printing with resin tends to more expensive and messy than FDM printing.

Retraction:

The distance the extruder pulls back the filament from the nozzle of an FDM printer.  Can be adjusted in .5mm increments to reduce stringing.

Skirt:

A ~2mm ring of filament printed around an object before the object begins to print.  Unlike a brim, a skirt does not touch the object and is not useful for plate adhesion.  Skirts are useful to check z-offset distances and filament flow before the actual print begins.

SLA:

Stereolithography, a type of 3D printing that uses a UV laser to solidify liquid resin.

STL:

Stereolithography, a file type for 3D objects.  Most slicing software will accept STL files.

Slicer:

The software that converts an STL file into a printable .gcode.  Most slicers will also have options to adjust print settings.

Supports:

The filament printed beneath an object to provide structure when there is not another layer of integral filament to attach to.  Supports should always be considered in FDM print object design, and can be difficult to remove.

TPU:

Thermoplastic Polyurethane, a flexible filament for FDM printers.  TPU is not very strong, but has a rubbery texture and is useful for flexible prints.

Vase Mode:

A slicer software setting that can be activated to instruct an FDM printer to print a single outer layer filament in the shape of the desired object.  Vase mode prints must have one open end (like a vase).

VOC:

Volatile Organic Carbon, VOCs are produced when filament is heated and extruded.  Some potential VOCs include ammonia, benzene, and phenol.  At high enough concentrations, inhaling these fumes can cause serve illness in humans.  Proper ventilation and consideration of materials used in 3D printing will assist is limiting your exposure to VOCs.

Warping:

An incredibly annoying FDM 3D printing issue, wherein the edges of a print lift slightly off the build plate.  This causes the succeeding layers of filament to become compressed, ruining the entire print.  Adding a brim and adjusting the z-offset can alleviate this issue.

Z-Offset:

An adjustable distance between the nozzle and the build plate.  In movies, people often start a 3D print and then walk away.  That is because movies lie.  Actual FDM printing means starting a print, waiting 5-10min for the printer to level and heat up, and then getting eye level with the print bed to make sure that the filament is extruding at exactly the right distance from the plate, and then incrementally adjusting the Z-offset if it is not.  They never show this in movies, because people would walk out of the theater.