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Welcome to the Harold Edward Cable Makerspace's guide for 3D Printing! 3D printing is a great resource for turning out quick prototypes, creating cool gifts, and bringing ideas to life. Whether you're a seasoned maker or just starting, our Makerspace offers you the tools and support you need to bring your projects to life.

It is highly recommended to take the 3D printing training that is offered at our space (Calendy Link) before using the 3D printers themselves. The trainings are only about 30 minutes long and familiarize students with the basics of PrusaSlicer, starting a print and general guidelines.

Before we get started, there are a few quick ground rules for using our 3D printers.

Quick Ground Rules

1. Our 3D printers cannot be used for resale, commercial-scale production or be used as an “assembly line” for profit
2. Please be aware of our policy on weapons “In accordance with Dartmouth College policy, The Cable Makerspace prohibits any production of weapons, ammunition, weapon accessories (including but not limited to containers and enhancements) and simulations or of any of the items listed above. This policy applies regardless of functionality or intended use. Those found in violation will lose access to Cable Makerspace indefinitely.”
3. Please design your models mindfully to minimize plastic waste (see a TA if your print is over 12 hours)
1. Consider options to create quick, sustainable prototype prints before creating the final prototype (see “How to Create Sustainable Prints” section below)
4. Please follow all of our general guidelines for using 3D printers
1. Use a “printer card” when starting a print!
2. Use the correct printer for your project. (Please note that we have limited amounts of printers for coursework; Thayer students, please see the MSHOP to expedite coursework-related prints.)
3. Please be mindful of the number of printers available, especially during peak use times. (See a TA if your project requires multiple printers)
4. Make sure your print is tuned to all the right settings on PrusaSlicer before exporting to the SD card
5. Watch the first layer — this is not an optional step and can seriously damage the extruder if “blobbing” occurs (email harold.edward.cable.makerspace@dartmouth.edu for any printer issues)

When to (and not to) 3D Print

To use 3D printing effectively, there are certain scenarios to recognize when 3D printing is the best option and when another manufacturing method may be better.

Some Quick Examples of What Not to 3D Print

• Boxes
• Way cheaper and less time-consuming to just laser-cut
• Typically faster to just use subtractive manufacturing methods (laser cutting, CNC, etc)
• Plates/Disks
• Cheaper and faster to just laser cut or CNC
• Resulting 3D printed products are typically less durable than alternatives
• Rods
• Time-consuming to print vertically and may be cheaper/faster to buy
• Rods lose their shape when printed horizontally

There are always exceptions to these rules! If your project fits in one of these categories, please come to a TA if you feel like you have a compelling argument and we can help you get set up with the optimal printing settings.

Difference Between 3D Printing & Other Fabrication Methods

Injection Molding

Injection molding is a manufacturing process used in large mass-industrial practices to create exact replicas of products that have complicated geometries. Molded products are created by injecting heated plastics into a mold which are then cooled and solidified. 3D printing can offer similar complex features but are not as precise as injection molding.

Thermoforming

Thermoforming transforms a plastic sheet into objects by applying heat, vacuum, and pressure. This method can create thin-walled objects that are hollow and can be advantageous compared to 3D printing.

Subtractive Methods (Mill/ Laser Cutter)

Both processes involve the controlled removal of material through either drilling or through a laser to create a desired part. In some instances, it is faster to cut out objects than to 3D print.

Note: A laser cutter can only create objects in the X & Y dimensions but a CNC mill can create features in all X, Y, & Z dimensions.

All of these machines are available through the Dartmouth Thayer Machine Shop — in certain scenarios, these options may be better than 3D printing!

3D Printers At Our Makerspace

Original Prusa i3 MK3S Printer

• Build volume - 25 cm x 21 cm x 21 cm (9.84” x 8.3” x 8.3”)
• Layer height - 0.05 - 0.35 mm

The Prusa MK3S are often standard 3D printers within educational and industrial settings. These printers only support one filament at a time while printing but can support up to a large variety of filaments such as PLA, PETG, ABS, and more.

Original Prusa XL - 2T Input Shaper

Build volume - 36 cm x 36 cm x 36 cm (14.17” x 14.17” x 14.17”)

The Prusa XL supports a large build plate and dual extruders, allowing users to print with two different types of filament. For examples, users can combine two different colors of PLA or PLA with PVA supports.

Note: To use the Prusa XL, please fill out the following Google Form. Please expect up to 1-5 business days to enter in the queue to print your project.

From CAD to a 3D Model

1. CAD

There are many CAD programs (SolidWorks, Fusion360, TinkerCAD, etc) available for users to start modeling their parts — this is a good stage to think about the tolerances, overhangs, and features that will be printed

Resources w/ CAD

For many users, TinkerCAD is an easy-to-use and friendly alternative for beginners. Blendr is a free program that offers more advanced features. Both have extensive tutorials available online.

2. .STL File

After a CAD model is finalized, it is important to save or export the file as a .STL file which is a stereolithography file. In other words, the CAD program translates the complex geometries into triangulated surfaces.

MShop also has several 3D scanners that can directly convert a readily available model into digital models.

Websites w/ FREE STL Files

It is possible to skip directly to this step without creating a model within CAD if it is already available on the Internet! A simple search of the part/object name that you're seeking followed by “STL file” is usually enough to bring up completed files. Here are some of the most popular sites to search for free STL files — please note that some sites offer STL files for sale.

Research-Geared STL Sites

(note that some models may be for sale)

— Medical Scans STL

— Other

For those interested in Biomedical 3D printing — see this tutorial on converting CT scans (using Democraiz3D), choosing which models to print, and cleaning up prints….

3. Slicer Program

There are many slicer programs available but PrusaSlicer is generally the slicer software that is used within our MakerSpace. At this point, the software “slices” the model into individual layers and creates a 2D outline for each layer that stacks up to form the 3D model gradually.

For a quick overview of PrusaSlicer, please see this resource on how to get set up.

Some important parameters to consider at this point are part orientation, layer height, infill, and supports. These are all covered in the links below:

Quick Start Guide (Please see this first!!!)

Prusa First Print

Modeling with 3D Printing in Mind

PrusaSlicer Playlist (Youtube Playlist of PrusaSlicer Tutorials)

Some quick slicer settings to pay attention to:

• Layer Height
• This refers to the height of each layer of the print. A small layer height typically means finer detail (and weaker parts) but a longer print time. The reverse is true for a large layer height. Typically values of 0.15 - 0.20 mm (Quality or Speed) are standard settings.
• Infill
• Oftentimes, printing with completely solid pieces is a waste of time and resources. Prints are often hollow with a certain infill percentage (based on strength requirements) and infill pattern. See these links for increasing part strength (Increase Part Strength, Infill Patterns). A good rule of thumb is to use gyroid for standard prints (fast print times and relatively high strength).
• See this for a complete guide to infills (Complete Guide — Super Helpful!!!)
• Perimeters/Shell Thickness
• This represents the number of lines on the outer walls — the walls will be completely solid and can significantly impact the strength of the 3D print. However, thicker walls will mean an increased print time.
• Supports
• Supports are integral to 3D printing and are used to support overhanging features on a 3D print. Sometimes, supports can be avoided altogether with the orientation of a print. It is also recommended to change the support type to organic instead of the default grid (easier to remove in most cases).
• Some helpful guides: support settings (basics), support material (Prusa),
• Adhesion Assistant
• Sometimes prints may have bad “bed adhesion” (or how well the print sticks to the build plate) due to various reasons. There are three different types of “adhesion assistants” that can try to improve the adhesion between the first layer and the plate. For a more in-depth review, see this guide
• Skirt — a distant and detached perimeter that outlines a print
• Brim — concentric rings that expand outwards of a print (good for prints with small “footprints” or a small contact area)
• Raft — an entire part on its own on upon which the model is printed on (can help with warping)

Modifiers

Modifiers can apply specific printing settings (such as infill, perimeters, supports, etc) to only specific regions of a print. For example, you may have a specific part of a print where you'd like to increase the strength by increasing infill to 100% but you'd like to keep the rest of the print at 15% infill to keep printing times low. Modifiers can also be used as boolean objects to create holes/gaps within the 3D print by setting the infill to zero.

• For a list of resources see: modifiers tutorial, modifiers (Prusa)

As always, if you're not sure of what you are doing, please come and talk to a TA! We'd love to help you get started.

Filament Types

There are various filament types with different properties based on the requirements of your project! The MakerSpace has different available filaments (PLA, ABS, PETG, FLEX) based on the current supply. Different filaments have different strengths and heat tolerances and all of these can be printed within the Makerspace!

Please come talk to a TA if printing with a filament other than PLA or if you wish to bring your own filament. Different filaments have varying nozzle temperatures and could potentially damage the build plate.

4 & 5. Machine Code and Print Time

Once the model is sliced, PrusaSlicer creates a file with the extension .gcode. This file essentially directs the extruder (moves in X, Y, and Z) and the build plate where to move and where to deposit filament onto the build plate. At this point, there is nothing more for the user to do!

6. Post-Processing

After the print has finished, many parts require post-processing steps such as removing support material, adding thread inserts/nuts, curing, etc.

Removing Supports

Waiting until the print has completely cooled down before removing supports results in a much cleaner result. Typically, support structures will have a lower density which makes it easier to break off.

Some tools that are very helpful for removing supports are:

• Needle-nose Pliers
• X-Acto Knives
• Flush Wire Cutter
• Files and Sandpaper

Typically flush wire cutters and pliers can be used to “snap off” support material which can result in easier removal. Sometimes, there will also be surface imperfections on the model which can be smoothed over with filing and sandpaper. Further, it may be easier to remove “organic supports” vs. grid supports.

Heat Inserts/Nuts

It is often better to incorporate threaded inserts or nuts into the print rather than 3D printing threads. If printing with threads is unavoidable, larger thread sizes yield better results with 3D printing (see this guide).

The concept of a heat insert is relatively simple: a small metal component (typically brass) is typically heated up using a soldering iron and pressed into a hole in the 3D printed part. Once the plastic cools and solidifies around the insert, this creates a strong and reliable threaded connection for screws. There are limited supply/amounts of different types of heat inserts available in the MakerSpace.

Some things to pay mind to are the melting point of the plastic, tolerance of the hole/insert, and counterbore hole specs.

Here are some good resources to follow: heat insert guide, heat insert video

Nuts can also be used in replacement of heat inserts for threaded connections. To incorporate nuts into 3D models, a simple cavity on the side of the print can be created or a shape can be extruded inwards of the print.

Snap Fits

Snap-fit joints can be incorporated early on into the design process to connect 3D components using interlocking features. The two most popular types of snap-fit connectors are cantilever and annular joints.

To create snap fits, please see these resources:

• designing snap fits (Hubs)
• snap-fit joints guide (All3DP)

As always, there are plenty of free snap-fit creations online and tutorials on YouTube.

Finishes

If you're looking to prime and paint your 3D print, there are many great guides and resources available! The basis concept is relatively straightforward — 3D prints need to have supports removed, sanded to remove slight imperfections, primed and then painted over. If you're interested in this avenue, see these resources below (note: Thayer M018 has a specific paint room with proper ventilation for these projects):

Prime and Paint Guide (formlabs)

Different 3D Print Finishes (fabheads)

Finish and Paint Guide (markforged)