Supports and bridges are the tools that let you print shapes that would otherwise sag, collapse, or deform during printing. Understanding when you need them and how to configure them saves wasted material and print failures.
How Overhangs Fail
When plastic extrudes beyond the solid layer below it, gravity pulls the molten plastic downward. If the overhang is small (under 10°), the cooling plastic can bridge the gap. If it’s large (over 45°), it sags and deforms.
Angle matters:
- 0-30° from horizontal: usually prints fine without support
- 30-45°: may sag slightly but usually succeeds
- 45-60°: requires support or produces poor quality
- 60°+: definitely needs support
Support Types
Linear Supports (Grid)
Straight vertical lines from the bed to underhanging features. Fastest to generate, use minimal material, but harder to remove.
When to use: Small overhangs, models on small beds, tight budgets
Pros: Fast print, minimal material
Cons: Harder to snap off, may leave divots in the surface
Tree Supports
Branch-like structures that follow the overhang contour, using less material and touching the model only where necessary.
When to use: Large overhangs, intricate geometry, detail-focused models
Pros: Fewer contact points, cleaner surfaces, significantly less waste
Cons: Slower to generate in slicer, sometimes fails with tiny branches
Custom Supports
You manually place support structures in your CAD model before slicing. Professional approach, gives you control.
When to use: Complex industrial parts, repeated prints, zero-waste requirement
Pros: Perfect optimization, minimal material waste
Cons: Requires CAD skills, time-intensive
Configuring Supports in Cura
Access: Slicer → Support → Enable Supports
Key settings:
Support Type: Tree (recommended) or Linear (faster)
Z-Distance: How far the support keeps from the model surface (0.2mm typical)
- Too small (0.1mm): Hard to remove, marks the surface
- Too large (0.5mm): Overhang still sags slightly
- Sweet spot: 0.2-0.3mm
Support Density: Percentage of lines within the support structure (15-20% typical)
- 10%: Minimal material, may collapse under its own weight
- 20%: Standard, reliable, good balance
- 30%: Over-engineered, wastes material
Interface Layers: Extra-dense layers at the support/model contact (3-5 layers typical)
- Helps support stick to model
- Makes removal cleaner
- Adds only 5-10 minutes to print time
Pro tip: Enable “Support Roof” (extra dense top of support). One mm of dense support roof eliminates 90% of surface marking from support contact.
Bridges Without Supports
A bridge is plastic extruded across a gap. The key is cooling. If the plastic cools before sagging, it holds shape.
Bridge settings in Cura:
- Bridge Settings → Enable Bridge: Cura will detect bridging and adjust speed/cooling
- Bridge Speed: Usually 50-70mm/s (slower than normal)
- Bridge Fan Speed: 100% (maximum cooling)
Real-world bridging:
- Spans under 10mm: Usually work fine without support
- Spans 10-20mm: May sag slightly but often acceptable
- Spans over 20mm: Needs support for reliable results
Test: Print a horizontal bridge over a 10mm hole, then a 20mm hole. This teaches you your printer’s bridging capability.
When NOT to Use Supports
Supports add 20-50% material and 30-100% print time. Skip them if:
- The overhang angle is under 30°
- The gap being bridged is under 15mm
- You can rotate the model to eliminate overhangs
- The underneath surface doesn’t matter (will be glued to something)
Smart move: Before enabling supports, rotate your model in the slicer. Many models print better at different angles, eliminating the need for supports entirely.
Support Removal
Tree supports: Usually snap cleanly with pliers. Twist and bend, they’ll release. Sand any remaining marks.
Linear supports: More stubborn. Use a flush cutter to shave material flush with the model, then sand smooth.
Damage prevention:
- Use a 0.3mm Z-distance instead of 0.2mm if the surface needs to be pristine
- Print a support roof (dense layers at contact)
- Keep alcohol or acetone nearby to smooth remaining material
Material Cost vs. Quality
A small model (10g filament) might use 5-10g of support. That’s $0.10-0.25 in wasted material.
A large model (50g) might use 20-30g of support. That’s $0.50-1.00 wasted.
For one-off prints, this is acceptable. For production or cost-sensitive work, invest time in model rotation or custom support design to minimize waste.
Common Mistakes
Over-supporting: Using linear supports for everything. Tree supports save 30-50% material with similar reliability.
Insufficient density: Setting support density below 15%. Supports collapse and ruin prints.
Wrong orientation: Printing models where a 90° rotation eliminates overhangs entirely. Always check before adding supports.
Forgetting support plates: Tree supports grow from the bed. If no plate is under them, they’ll collapse mid-print. Ensure your slicer places supports on the bed, not floating.
Master supports and bridges, and you can print nearly any geometry. Most failure-free prints use smart support strategy rather than perfect settings. Spend the slicer time up front; it pays off in print success.