3D Printing

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3D Printing
Creating mechanical parts from plastic filament using FDM printing
Difficulty Range Beginner to Advanced
Time to Basic 1-2 weeks
Essential Tools FDM 3D printer ($200-400), PLA filament, slicer software
Optional Tools Calipers, flush cutters, deburring tool, adhesives
Get Started 3D Printing Basics
Unlocks (Basic) Custom chassis, sensor mounts, brackets, wheels
Unlocks (Advanced) Complex assemblies, living hinges, parametric designs, embedded hardware

3D Printing is the competency of fabricating mechanical parts from digital designs using additive manufacturing. In robotics, 3D printing is the most accessible and affordable way to create custom chassis, brackets, sensor mounts, wheels, and structural components.

This competency focuses specifically on FDM (Fused Deposition Modeling) printing - the cheapest and most common technology for hobbyist robotics. It's about the hands-on technique of turning digital CAD files into physical parts that work on real robots.

3D Printing is distinct from CAD Design (creating the digital models) and Mechanics (understanding mechanical principles). This competency focuses on the fabrication process itself: preparing models for printing, selecting settings, troubleshooting failures, and finishing parts.

Why 3D Printing Matters for Robotics

3D printing revolutionized hobbyist robotics by eliminating barriers to custom mechanical design:

  • Affordability - Print custom parts for pennies instead of machining for dollars
  • Rapid iteration - Redesign and reprint in hours, not weeks
  • Complex geometry - Create shapes impossible to machine or cut
  • No tooling - No need for mills, lathes, or specialized equipment
  • On-demand manufacturing - Print what you need, when you need it

Before accessible 3D printing, hobbyists were limited to:

  • Off-the-shelf kits with fixed designs
  • Simple laser-cut acrylic plates
  • Hand-cutting/drilling materials with limited precision
  • Expensive machine shop services

Now, anyone with a $200-400 printer can create professional-quality robot parts at home.

Skill Progression

Beginner (SimpleBot Level)

Skills you need to print and assemble SimpleBot parts:

  • Operating a printer - Bed leveling, loading filament, starting prints
  • Using slicer software - Import STL, basic settings, generate G-code
  • Print preparation - Bed adhesion, first layer success
  • Basic troubleshooting - Warping, layer adhesion, stringing
  • Post-processing - Removing supports, cleaning up prints, basic finishing
  • Assembly - Inserting hardware (screws, nuts, bearings) into printed parts

Unlocks:

  • Print SimpleBot chassis from provided STL files
  • Print sensor brackets and motor mounts
  • Print wheels and structural components
  • Assemble printed parts into working robots

Tutorials: 3D Printing Basics

At this level you can:

  • Print designs created by others (download STL files)
  • Successfully produce functional parts for your robot
  • Troubleshoot common print failures
  • Assemble printed parts with hardware

Intermediate (Custom Robot Parts)

Skills for designing and printing custom robot parts:

  • Design for FDM - Layer orientation, overhangs, support requirements
  • Tolerances and fit - Designing holes, slots, and assemblies that fit together
  • Print orientation - Choosing optimal orientation for strength and printability
  • Support strategies - When to use supports, how to minimize them
  • Advanced slicing - Variable layer height, infill patterns, perimeters
  • Material selection - PLA vs PETG vs TPU for different applications
  • Embedded hardware - Designing parts with captive nuts, heat-set inserts, bearings
  • Iterative design - Measuring, adjusting, reprinting efficiently

Unlocks:

  • Design custom chassis for your robot concept
  • Create mounting brackets for non-standard sensors
  • Design wheel hubs, motor mounts, and gearing
  • Print functional assemblies (hinges, latches, sliding parts)
  • Adapt designs for different motors/sensors/components

Tutorials: 3D Printing for Robotics

At this level you can:

  • Design parts from scratch that print successfully
  • Modify existing designs to fit your needs
  • Choose optimal print settings for different applications
  • Design multi-part assemblies that fit together
  • Troubleshoot dimensional accuracy issues

Advanced (Complex Mechanical Systems)

Skills for professional-grade printed mechanisms:

  • Parametric design - Use variables to create adjustable designs
  • Living hinges - Print flexible joints in rigid materials
  • Gear design - Print functional gears, belts, pulleys
  • Multi-material printing - Combining rigid and flexible materials
  • Thread design - Print functional threads for screws and bolts
  • Strength optimization - Anisotropy, layer lines, infill strategies for load-bearing parts
  • Tolerance stacks - Managing precision in complex assemblies
  • Material properties - Engineering plastics (nylon, polycarbonate, carbon fiber composites)
  • Surface finishing - Vapor smoothing, sanding, painting, coating

Unlocks:

  • Gripper mechanisms with printed flexures
  • Custom gearboxes and drivetrains
  • Ball bearing races and sliding mechanisms
  • Snap-fit enclosures and latches
  • Load-bearing structural components

Tutorials: Advanced FDM Techniques (stub)

At this level you can:

  • Design complex mechanisms entirely in plastic
  • Replace machined metal parts with optimized prints
  • Create production-quality assemblies
  • Push the limits of FDM technology
  • Teach others 3D printing for robotics

Learning Paths

Path 1: SimpleBot Builder (Beginner)

  1. Get a working FDM printer (Creality Ender 3, Prusa Mini, or similar)
  2. Complete 3D Printing Basics - First successful print
  3. Download SimpleBot STL files from the repository
  4. Print all SimpleBot parts (chassis, motor mounts, wheels, brackets)
  5. Assemble SimpleBot using your printed parts

Result: You can print robot parts designed by others and assemble them into working robots.

Path 2: Custom Parts Designer (Intermediate)

  1. Complete Path 1 (SimpleBot Builder)
  2. Learn basic CAD Design (FreeCAD, Fusion 360, or Onshape)
  3. Study 3D Printing for Robotics - Design principles for FDM
  4. Design a custom sensor mount for SimpleBot
  5. Iterate on the design (measure, adjust, reprint)
  6. Document your design as an implementation page

Result: You can design custom parts that integrate with existing robots.

Path 3: Mechanism Designer (Advanced)

  1. Complete Path 2 (Custom Parts Designer)
  2. Design a complete custom robot chassis from scratch
  3. Incorporate complex features (living hinges, embedded nuts, snap fits)
  4. Design multi-part assemblies (gripper, articulated arm, gearbox)
  5. Test and iterate on mechanical performance
  6. Share your design with the community

Result: You can design complete robots and complex mechanisms using 3D printing.

Essential Concepts

FDM Process Basics

Fused Deposition Modeling works by:

  1. Heating plastic filament (typically 190-220°C for PLA)
  2. Extruding melted plastic through a nozzle (typically 0.4mm)
  3. Depositing plastic in layers (typically 0.1-0.3mm thick)
  4. Building up layers to create 3D objects

Key parameters:

  • Layer height - Thinner = smoother, slower; thicker = faster, rougher
  • Nozzle temperature - Too hot = stringing; too cold = poor adhesion
  • Bed temperature - Prevents warping (60°C for PLA, 80°C for PETG)
  • Print speed - Faster = more failures; slower = higher quality

Material Selection for Robotics

  • PLA (Polylactic Acid) - Best for beginners
    • Easy to print, low warping, no fumes
    • Rigid but brittle
    • Good for chassis, brackets, non-load-bearing parts
    • Weakness: Low temperature resistance (softens >60°C)
  • PETG (Polyethylene Terephthalate Glycol) - Durable upgrade
    • Slightly harder to print than PLA
    • Flexible and impact-resistant
    • Good for wheels, motor mounts, stressed parts
    • Weakness: Prone to stringing
  • TPU (Thermoplastic Polyurethane) - Flexible rubber-like
    • Difficult to print (requires direct drive or slow speeds)
    • Excellent for tires, grips, shock absorption
    • Weakness: Cannot be load-bearing

For SimpleBot: PLA is sufficient for all parts. Upgrade to PETG for motor mounts and wheels if you want better durability.

Layer Orientation and Strength

FDM parts are anisotropic - strength depends on orientation:

  • Strongest: Load parallel to layers
  • Weakest: Load perpendicular to layers (layers can separate)

Example: A motor mount bracket should be oriented so forces push along layers, not pulling layers apart.

This is critical for robotics - a poorly oriented print can fail under load even with 100% infill.

Overhangs and Supports

FDM cannot print in mid-air. Overhangs are angles that extend beyond the previous layer:

  • <45° overhang - Usually prints fine without support
  • 45-70° overhang - May need support depending on geometry
  • >70° overhang - Definitely needs support

Bridging - Horizontal spans between two points (printer can do short bridges <20mm)

Supports are temporary structures that hold up overhangs during printing. They must be removed after printing, leaving marks on the surface.

Design strategy: Orient parts to minimize supports (faster, cleaner, stronger).

Tolerances and Fit

Printed parts have dimensional variation:

  • Typical accuracy: ±0.2mm (but varies by printer, material, settings)
  • Holes print smaller - Add 0.2-0.3mm to hole diameters
  • Shafts print larger - Subtract 0.2-0.3mm from shaft diameters

Clearance fits for robotics:

  • Press fit - 0.0mm clearance (part pressed in, stays tight)
  • Slip fit - 0.2mm clearance (parts slide together with friction)
  • Free fit - 0.5mm clearance (parts move freely, some wobble)

Example: For an M3 screw (3.0mm nominal):

  • Threaded hole - print 2.5mm, tap with M3 tap
  • Clearance hole - print 3.3-3.5mm (screw passes through freely)

Print Preparation and Settings

Slicing Software

Slicers convert STL files to G-code (printer instructions):

  • PrusaSlicer (free, open-source, excellent defaults)
  • Cura (free, user-friendly, widely used)
  • Simplify3D (paid, advanced features)

All slicers allow you to adjust:

  • Layer height, infill density, perimeters
  • Support generation and placement
  • Print speed, temperature, retraction
  • Bed adhesion (brim, raft, skirt)

Critical First Layer

The first layer determines success or failure:

  • Bed leveling - Nozzle must be exactly the right distance from bed
    • Too close = nozzle drags, clogs
    • Too far = poor adhesion, warping
  • Bed adhesion - Clean bed, appropriate temperature
  • First layer speed - Slower than normal (50% of print speed)
  • First layer height - Slightly thicker than other layers (0.2mm is common)

Tip: Watch the entire first layer. If it's not perfect, stop and restart.

Support Settings

When supports are needed:

  • Support type - Grid, lines, or tree supports
  • Support density - 10-20% typical (more = harder to remove)
  • Support Z-distance - Gap between support and part (0.2mm typical)
  • Support interface - Dense layer between support and part (easier removal, better surface)

Tip: Use support blockers/enforcers to add supports only where needed.

Infill Strategies

Infill is the internal structure (not visible on outside):

  • Infill density - 10-20% for most robotics parts (saves time and material)
  • Infill pattern - Grid, gyroid, honeycomb (gyroid is strong and fast)
  • Perimeters - 3-4 walls typical (outside strength comes from perimeters, not infill)

For structural parts: 30-50% infill + 4 perimeters is stronger than 100% infill + 2 perimeters.

Common Pitfalls

  • Skipping bed leveling - Single most common cause of failure. Level the bed every time.
  • Ignoring first layer problems - A bad first layer never gets better. Stop and restart.
  • Wrong temperature - Too cold = poor adhesion between layers (weak parts). Too hot = stringing, oozing.
  • Insufficient perimeters - Thin walls with high infill are weaker than thick walls with low infill.
  • Poor orientation - Printing with load perpendicular to layers = weak parts that snap.
  • Overusing supports - Supports waste time and material. Reorient parts to avoid them when possible.
  • Ignoring tolerances - Holes too small, shafts too big. Always test fit and adjust.
  • Wet filament - PLA absorbs moisture from air, causes bubbling and poor prints. Store in dry boxes.

Post-Processing Techniques

Support Removal

  • Use flush cutters to clip away supports
  • Pliers for larger support structures
  • Deburring tool or knife for cleaning up nubs
  • Sandpaper for smoothing support scars

Hardware Insertion

  • Heat-set inserts - Brass threaded inserts melted into plastic (strong, reusable threads)
  • Captive nuts - Design hexagonal pockets for nuts to drop into
  • Press-fit bearings - Print undersized holes, press bearings in for tight fit
  • Tapping threads - Drill/print undersized hole, cut threads with tap

Finishing

  • Sanding - Progressive grits (80 → 220 → 400) for smooth surface
  • Acetone vapor - ABS only (PLA doesn't respond)
  • Primer + paint - Automotive primer fills layer lines
  • Clear coat - Protects paint, adds gloss

Tools and Equipment

Essential Tools (Start Here)

  • FDM 3D Printer ($200-400) - Creality Ender 3, Prusa Mini, Artillery Sidewinder
  • PLA filament ($15-25/kg) - White, black, or colorful
  • Slicer software (free) - PrusaSlicer or Cura
  • Flush cutters ($5-10) - Remove supports and clean up prints
  • Spatula/scraper ($5-10) - Remove prints from bed

Intermediate Tools

  • Calipers ($15-30) - Measure parts and check tolerances
  • Deburring tool ($5-10) - Clean up edges and holes
  • Needle files ($10-20) - Fine-tune printed holes and slots
  • Isopropyl alcohol ($5-10) - Clean print bed for adhesion
  • Extra nozzles ($10-20) - 0.4mm spares, plus 0.6mm for faster prints

Advanced Tools

  • Heat-set insert tips ($20-40) - For soldering iron
  • Filament dryer ($30-60) - Keep filament moisture-free
  • Different materials ($20-30/kg) - PETG, TPU for specialized parts
  • Spare parts kit ($20-40) - Nozzles, hot end parts, belts, fans

Printer Recommendations for Robotics

Budget Entry ($200-300)

  • Creality Ender 3 V2 - Most popular beginner printer, huge community
  • Artillery Genius - Quieter, faster out-of-box experience

Mid-Range ($400-600)

  • Prusa Mini+ - Excellent reliability, open-source, great support
  • Creality CR-10 Smart - Larger build volume (300×300mm)

Premium ($800-1200)

  • Prusa i3 MK4 - Best-in-class, auto bed leveling, filament sensor
  • Bambu Lab P1S - Extremely fast, enclosed, multi-material capable

For SimpleBot: Any printer with 180×180×180mm build volume works. Ender 3 is excellent value.

Tutorials and Resources

BRS Tutorials

Robot Pages

External Resources

Related Competencies

  • CAD Design - Create the digital models to print (prerequisite for custom designs)
  • Mechanics - Understand forces, motion, and structural principles
  • Electronics - Design parts that house and protect electronics
  • Soldering - Insert heat-set inserts with soldering iron
  • Assembly - Put printed parts together with hardware

How 3D Printing Enables Capabilities

3D printing doesn't directly create Capabilities (which require sensors or actuators), but it enables capabilities by providing the mechanical structure:

Every capability needs mechanical support - 3D printing makes that support custom-fittable to your exact hardware.

See Also

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