April 10, 2024 3D Printing By Daniel Williams

3D Printing Your Models

Introduction to 3D Printing

3D printing has revolutionized the way we bring digital designs into the physical world. Whether you're a hobbyist, professional designer, or just curious about the technology, understanding how to prepare your 3D models for printing is essential for achieving successful results.

In this comprehensive guide, we'll cover everything you need to know about taking your 3D models from the screen to physical objects, including file preparation, design considerations, and optimization techniques for different 3D printing technologies.

Understanding 3D Printing Technologies

Before diving into model preparation, it's important to understand the different 3D printing technologies available, as each has its own requirements and limitations:

Fused Deposition Modeling (FDM)

The most common and accessible 3D printing technology:

Works by extruding melted thermoplastic filament layer by layer
Affordable and widely available
Limited resolution compared to other technologies
Requires support structures for overhangs
Common materials: PLA, ABS, PETG, TPU

Stereolithography (SLA) and Digital Light Processing (DLP)

Resin-based technologies that offer higher detail:

Uses light (laser or projector) to cure liquid resin layer by layer
Higher resolution and smoother surface finish than FDM
More expensive than FDM
Requires post-processing (washing and curing)
Limited build volume compared to FDM

Selective Laser Sintering (SLS)

Powder-based technology used for functional parts:

Uses laser to sinter powder particles together
No need for support structures
Strong, functional parts
More expensive and primarily used in professional settings
Common materials: Nylon, TPU, various composites

File Formats for 3D Printing

The standard file formats used in 3D printing include:

STL (STereoLithography)

The most common format for 3D printing:

Represents the surface geometry of the model using triangular facets
Simple and widely supported
Does not store color, material, or texture information
File size increases with model complexity

OBJ

A more versatile format:

Can include color and texture information
Widely supported across modeling and printing software
Larger file size than STL

3MF (3D Manufacturing Format)

A newer format designed specifically for 3D printing:

Stores model geometry, material, color, and texture
More compact than STL
Includes print settings and other metadata
Growing support but not as universal as STL

Preparing Your Model for 3D Printing

Checking for Printability

Before sending your model to a printer, ensure it meets these basic requirements:

Watertight Mesh

Your model must be a closed, watertight mesh with no holes or gaps:

Use software tools like Netfabb, Meshmixer, or your modeling software's built-in check tools
Fix non-manifold edges, intersecting faces, and reversed normals
Ensure all parts of the model are connected or separated intentionally

Wall Thickness

Models must have adequate wall thickness to print successfully:

For FDM printing: Minimum 0.8mm (2-3 times nozzle diameter)
For SLA/DLP: Minimum 0.5mm
For SLS: Minimum 0.7mm
Vary thickness based on structural requirements and material properties

Overhangs and Support Structures

Consider how your model will be printed layer by layer:

FDM printers typically struggle with overhangs beyond 45 degrees
Design with printability in mind to minimize supports
For unavoidable overhangs, ensure your slicing software generates adequate supports
Consider the orientation of your model to minimize support structures

Optimizing Model Geometry

Polygon Count Optimization

While high-polygon models provide detail, they can cause issues:

Very high polygon counts can slow down slicing software
The printer's resolution is the limiting factor, not polygon count
Use decimation tools to reduce polygons while maintaining important details
Focus detail where it matters most in the model

Model Orientation

How you orient your model affects print quality and strength:

Orient to minimize overhangs and support structures
Consider the layer orientation for structural integrity (parts are typically weaker along the Z-axis)
Flat surfaces on the build plate typically print better
Critical features should avoid being supported if possible

Slicing Your Model

Slicing is the process of converting your 3D model into instructions (G-code) that the 3D printer can understand:

Common Slicing Software

Cura: Free, open-source, works with most FDM printers
PrusaSlicer: Optimized for Prusa printers but works with others
Simplify3D: Paid software with advanced features
Chitubox: Popular for resin printers

Critical Slicing Parameters

Layer Height

Determines the resolution and print time:

Smaller layer heights (0.1mm) provide better detail but longer print times
Larger layer heights (0.2-0.3mm) print faster but with visible layers
Should be selected based on the printer's capabilities and your detail requirements

Infill Percentage and Pattern

Affects strength, weight, and material usage:

Lower infill (10-20%) for decorative models
Higher infill (50%+) for functional parts
Different patterns (grid, honeycomb, gyroid) offer different strength-to-weight ratios

Print Speed

Balances quality and print time:

Slower speeds generally produce better quality
Consider different speeds for different features (perimeters, infill, supports)
Adjust based on your printer's capabilities and material

Material-Specific Considerations

FDM Materials

PLA (Polylactic Acid)

Easiest to print, biodegradable
Good for decorative models
Lower temperature resistance (softens around 60°C)
Print temperature: 190-220°C
Bed temperature: 50-60°C or room temperature

ABS (Acrylonitrile Butadiene Styrene)

More durable and heat-resistant than PLA
Prone to warping, requires heated bed
Releases fumes during printing, requires ventilation
Print temperature: 230-250°C
Bed temperature: 100-110°C

PETG (Polyethylene Terephthalate Glycol)

Balance between PLA ease of printing and ABS durability
Good water resistance
Less prone to warping than ABS
Print temperature: 230-250°C
Bed temperature: 70-80°C

Resin Materials (SLA/DLP)

Standard resins: Good detail but brittle
Tough resins: More durable but more expensive
Flexible resins: For rubber-like parts
Specialty resins: Castable, dental, biocompatible

Post-Processing Your Prints

FDM Post-Processing

Support removal: Carefully remove supports with pliers or flush cutters
Sanding: Start with coarse grit (80-120) and work up to fine (220+)
Gap filling: Use putty or resin to fill layer lines
Painting: Use primer first, then acrylic or model paints

Resin Post-Processing

Washing: Clean uncured resin with isopropyl alcohol
Curing: Expose to UV light to fully cure
Support removal: Remove after washing but before final curing
Sanding: If needed, use fine sandpaper (400+ grit)

Troubleshooting Common 3D Printing Issues

FDM Issues

Stringing: Adjust retraction settings
Layer separation: Increase temperature or check for drafts
Warping: Use a heated bed, apply adhesive, or add a brim
Under-extrusion: Check for clogs or increase flow rate

Resin Issues

Failed supports: Increase support thickness or density
Incomplete parts: Increase exposure time
Cloudy finish: Ensure proper washing and curing

Conclusion

Successfully 3D printing your models requires understanding the technology, proper model preparation, and appropriate settings for your specific printer and material. While there's a learning curve, the ability to bring your digital creations into the physical world is incredibly rewarding.

Remember that 3D printing is often an iterative process. Don't be discouraged if your first attempts aren't perfect—each print provides valuable feedback that you can use to improve future results. With practice and patience, you'll soon be creating impressive 3D printed models from your digital designs.

In our next article, we'll explore advanced texturing techniques to enhance the visual quality of your 3D models before printing or rendering.