Fused Deposition Modelling (FDM) is a popular 3D printing technology known for its affordability and wide range of filament materials. If you’re new to designing for FDM printing. this guide will equip you with the knowledge to design parts that optimize for its the capabilities .
Wall Thickness and Orientation:
- Minimum Strength: Maintain a minimum wall thickness of 1.2mm for vertical walls to prevent warping. Walls with horizontal support can be slightly thinner (1.0mm).
- Overhangs and Bridges: FDM printers struggle with unsupported features that jut outwards (overhangs) or bridge gaps between unsupported areas. To avoid printing issues, limit overhang angles to 45 degrees or less. Consider adding support structures in your design software or redesigning parts to minimize overhangs and bridges.
- Warping Reduction: Thicker walls (around 3-5mm) at the base of your design can help reduce warping, especially for tall prints.
Holes and Threads:
- Minimum Feature Size: Design holes and pins with a minimum diameter of 1mm for accurate printing. Smaller features may become clogged or break easily.
- Thread Design: Avoid sharp corners when designing threads. Instead, opt for rounded roots and crests (ACME threads) for improved strength. Consider tapping threads after printing for parts requiring high precision.
Clearances and Assembly:
- Frictionless Movement: Include a clearance of at least 0.5mm between mating parts to prevent them from sticking together after printing.
- Snap Fits: Design snap-fit features with a slight interference between parts (0.1 – 0.2mm) for secure connections.
Surface Features and Text:
- Visible Details: Ensure embossed features have a height of at least 0.3mm and engraved features have a minimum depth and width of 0.5mm to be visible on the final printed part.
- Text Clarity: Use bold text with a minimum size of 16 points on the top or bottom surfaces, and 10 points on vertical walls. Vertical text may require removing support structures after printing, which can add time.
Additional Considerations:
- Filament Choice: The ideal filament material depends on your application. Consider factors like strength, flexibility, heat resistance, and desired finish.
- Strength: Think about how the part will be printed when designing. FDM prints are usually oriented with the flattest surface on the build plate and layer are built up from this face. The natural weakness of an FDM print will be in the Z orientation so features requiring strength should be printed horizontally.