Prepare Print Model

步骤

1. Export Model from Source Software

Export the 3D model in a suitable format for printing:

For FDM/SLA:

# If starting from CAD (Fusion 360, SolidWorks)
# Export as: STL (binary) or 3MF
# Resolution: High (triangle count sufficient for detail)
# Units: mm (verify scale)

# Example export settings:
# STL: Binary format, refinement 0.1mm
# 3MF: Include color/material data if using multi-material printer

预期结果： Model file exported with appropriate resolution (0.1mm chord tolerance for mechanical parts, 0.05mm for organic shapes).

失败处理： Check that model is fully defined (no construction geometry), no missing faces, all components visible.

2. Verify Mesh Integrity

Check that the mesh is manifold and printable:

# Install mesh repair tools if needed
# sudo apt install meshlab admesh

# Check STL file for errors
admesh --check model.stl

# Look for:
# - Non-manifold edges: 0 (every edge connects exactly 2 faces)
# - Holes: 0
# - Backwards/inverted normals: 0
# - Degenerate facets: 0

Common issues:

• Non-manifold edges: Multiple faces share an edge, or edge has only one face
• Holes: Gaps in mesh surface
• Inverted normals: Inside/outside of model reversed
• Intersecting faces: Self-intersecting geometry

预期结果： Report shows 0 errors, or errors are repairable.

失败处理： Repair mesh automatically or manually:

# Automatic repair with admesh
admesh --write-binary-stl=model_fixed.stl \
       --exact \
       --nearby \
       --remove-unconnected \
       --fill-holes \
       --normal-directions \
       model.stl

# Or use meshlab GUI for manual inspection/repair
meshlab model.stl
# Filters → Cleaning and Repairing → Remove Duplicate Vertices
# Filters → Cleaning and Repairing → Remove Duplicate Faces
# Filters → Normals → Re-Orient all faces coherently

If automatic repair fails, return to source software and fix modeling errors (coincident vertices, open edges, overlapping bodies).

3. Check Wall Thickness

Verify minimum wall thickness for chosen process:

Minimum wall thickness by process:

# Check wall thickness visually in slicer:
# - Import model
# - Enable "Thin walls" detection
# - Slice with 0 infill to see wall structure

# For precise measurement, use CAD software:
# - Measure distance between parallel surfaces
# - Check in critical load-bearing areas

预期结果： All walls meet minimum thickness for chosen process. Thin walls flagged for review.

失败处理： Return to CAD and thicken walls, or:

• Switch to smaller nozzle (FDM)
• Use "detect thin walls" slicer setting
• Accept reduced strength for prototypes

4. Determine Print Orientation

Select orientation to optimize strength, surface finish, and support usage:

Orientation decision matrix:

For strength:

• Orient so layer lines run perpendicular to primary load direction
• Example: Bracket under tension → print vertically so layers stack along load axis

For surface finish:

• Orient largest/most visible surface flat on bed (minimal stair-stepping)
• Critical dimensions aligned with X/Y plane (higher precision than Z)

For minimal supports:

• Minimize overhangs >45° (FDM) or >30° (SLA)
• Place flat surfaces on bed when possible

Load direction analysis:

If part experiences:
- Tensile load along axis → print with layers perpendicular to axis
- Compressive load → layers can be parallel (less critical)
- Bending moment → layers perpendicular to neutral axis
- Shear → avoid layer interfaces parallel to shear direction

预期结果： Orientation chosen with explicit rationale for strength, finish, or support tradeoffs.

失败处理： If no orientation satisfies all requirements, prioritize in order: functional strength → dimensional accuracy → surface finish → support minimization.

5. Generate Support Structures

Configure automatic or manual supports for overhangs:

Support angle thresholds:

• FDM: 45° from vertical (some bridging up to 60° possible)
• SLA: 30° from vertical (less bridging capability)
• SLS: No supports needed (powder bed support)

Support types:

Tree supports (FDM, recommended):

• Fewer contact points with model
• Easier removal
• Better for organic shapes
• Configure: Branch angle 40-50°, branch density medium

Linear supports (FDM, traditional):

• More stable for large overhangs
• More contact points (harder removal)
• Configure: Pattern grid, density 15-20%, interface layers 2-3

Heavy supports (SLA):

• Thicker contact points for heavy parts
• Risk of marks on surface
• Configure: Contact diameter 0.5-0.8mm, density based on part weight

Interface layers:

• Add 2-3 interface layers between support and model
• Reduces surface marks
• Slightly easier removal

# In slicer (PrusaSlicer example):
# Print Settings → Support material
# - Generate support material: Yes
# - Overhang threshold: 45° (FDM) / 30° (SLA)
# - Pattern: Rectilinear / Tree (auto)
# - Interface layers: 3
# - Interface pattern spacing: 0.2mm

预期结果： Supports generated for all overhangs exceeding threshold angle, preview shows no floating geometry.

失败处理： If automatic supports inadequate:

• Add manual support enforcers in critical areas
• Increase support density near thin overhangs
• Split model and print in sections if supports infeasible

6. Configure Slicer Profile

Set process-appropriate parameters:

FDM layer heights:

• Draft: 0.28-0.32mm (fast, visible layers)
• Standard: 0.16-0.20mm (balanced quality/speed)
• Fine: 0.08-0.12mm (smooth, slow)
• Rule: Layer height = 25-75% of nozzle diameter

SLA layer heights:

• Standard: 0.05mm (balanced)
• Fine: 0.025mm (miniatures, high detail)
• Fast: 0.1mm (prototypes)

Key parameters by process:

FDM:

layer_height: 0.2mm
line_width: 0.4mm (= nozzle diameter)