Sanding

Sanding and Surface Preparation

Sanding is essential for achieving smooth, professional finishes on 3D-printed components. The process varies by material and application:

• Grit Progression: Begin with 220-grit sandpaper for most materials (e.g., PLA) to remove visible layer lines without distorting details. Progress to 800–2000 grit for polished surfaces. Lower grits (e.g., 180) may be used for hard plastics but risk heat-related deformation.

• Material-Specific Tips:

  • ABS: Sands more easily than PLA; start with 240–320 grit.

  • CosPLA (Polymaker): Formulated for easier sanding, ideal for cosplay/prop applications.

• Tools and Techniques:

  • Power Sanders: Effective for flat surfaces; avoid prolonged contact to prevent heat buildup (critical for PLA).

  • Dremel Tools: Useful for intricate areas but require careful handling to avoid melting or gouging.

  • Wet Sanding: Reduces dust and heat; use with 400+ grit for fine finishes.

Bondo (Automotive Body Filler)

Bondo is a high-strength filler for sealing large seams or gaps in functional parts.

• Application: Ideal for load-bearing joints or structural repairs.

• Challenges:

  • Sanding Difficulty: Requires electric sanders or rotary tools; manual sanding is ineffective.

  • Heat Sensitivity: Risk of melting PLA during aggressive sanding.

• Best Practices: Apply sparingly to minimize post-processing; avoid 90-degree angles due to sanding limitations.

Spackle (Lightweight Filler)

Spackle is suited for non-functional, display-oriented models.

• Pros:

  • Ease of Use: Spreadable by hand into fine gaps; sands easily with 800+ grit paper.

  • Quick Drying: Ready for sanding within 30 minutes.

• Cons:

  • Low Durability: Prone to dents/scratches; unsuitable for mechanical parts.

  • Limited Strength: Avoid applications requiring stress resistance.

Model Putty

Model putty bridges the gap between Bondo and Spackle, offering moderate strength with manageable sanding requirements.

• Use Cases: Small-to-medium seams needing durability without extensive finishing.

• Sanding: Expect more effort than Spackle but less than Bondo; ideal for detailed cosmetic repairs.

Material-Specific Guidelines

• PLA: Prioritize progressive sanding; avoid high-speed tools on thin walls.

• ABS: Tolerates aggressive sanding; pair with acetone smoothing for glossy finishes.

• Functional Parts: Use Bondo or epoxy fillers for structural integrity.

• Display Models: Opt for Spackle or model putty for quick, low-stress fixes.

Note: Always test fillers/adhesives on scrap prints to assess compatibility and finish quality.