3D Print Support Structures: When and How to Use Them

Support structures are temporary scaffolding that your 3D printer builds alongside your model to hold up overhanging sections. Knowing when to use them, which type to choose, and how to configure them for easy removal is essential for every 3D printing enthusiast.

When Do You Need Support Structures

The general rule in FDM printing is the 45-degree rule: any overhang steeper than 45 degrees from vertical needs support. However, this depends on your printer, material, and cooling:

• PLA with good cooling: Can handle 55-60 degree overhangs without support
• PETG: Stick to the 45-degree rule; PETG does not bridge as well as PLA
• ABS: Similar to PETG. Less forgiving of steep overhangs
• Bridges: Spans up to 50 mm can bridge without support in PLA with 100% fan speed

Parts that almost always need support include: figurines with outstretched arms, T-shaped parts, models with horizontal holes, and any feature hanging in mid-air.

Types of Support Structures Explained

Linear/Normal supports are grid-like columns that grow straight up from the build plate. They are reliable but can be difficult to remove and leave marks on the surface.

Tree supports (Cura) grow like tree trunks and branches, touching only where needed. They use less material, are easier to remove, and leave less scarring. However, they take longer to generate and may not support every geometry reliably.

Organic supports (PrusaSlicer/OrcaSlicer) are similar to tree supports but use a different algorithm. Many users find them even easier to remove than Cura’s tree supports.

Soluble supports use a second material (like PVA with PLA, or HIPS with ABS) that dissolves in water or limonene. They give the cleanest results but require a dual-extruder printer.

Support Settings in Cura and PrusaSlicer

Essential support settings to configure:

• Support placement: “Touching buildplate” only places supports that start from the bed. “Everywhere” adds supports between layers of the model too. Start with “Touching buildplate” and only switch to “Everywhere” if you see unsupported overhangs
• Support density: 15-20% is standard. Lower density uses less material and removes more easily, but may sag between support lines
• Support Z distance: The gap between support top and your model’s bottom surface. 1 layer height (0.2 mm) is standard. Increase to 0.3 mm for easier removal
• Support X/Y distance: Horizontal gap between support and model walls. 0.7-1.0 mm prevents support from fusing to vertical walls
• Support interface layers: Dense layers at the top of supports that create a smoother surface. 2-3 interface layers at 80-100% density give the best surface finish on supported areas

Tree and Organic Supports

Tree supports have revolutionised support removal in 3D printing:

• They touch the model at minimal points, making removal nearly effortless
• They can reach around obstacles to support internal features
• They use 30-50% less material than normal supports
• Cura’s tree supports work best for figurines, statues, and organic shapes
• PrusaSlicer’s organic supports are particularly effective for mechanical parts with overhanging features

When to avoid tree supports: Very small, precise features (like screw holes) are better supported with normal supports that provide a flat, reliable surface.

Tips for Easy Support Removal

Even with the right settings, support removal requires some technique:

1. Use needle-nose pliers: Grip the support at its base and twist gently. Do not pull straight away from the model surface
2. Score the support interface: Run a craft knife along the line where support meets the model before removing
3. Warm the part slightly: A heat gun on low for 10-15 seconds softens PLA supports for easier removal
4. Sand the supported surface: Start with 120-grit and work up to 400-grit for a smooth finish on supported areas
5. Support interface material: In multi-material printers, use PVA or breakaway filament for the interface layer only

Designing Parts to Minimise Supports

The best support is no support. Design your parts to minimise or eliminate the need:

• Split the model: Cut the part at a flat plane, print both halves flat-side down, and glue them together
• Orient for minimal overhangs: Rotating the model 45 degrees often eliminates supports entirely
• Use chamfers instead of overhangs: A 45-degree chamfer on the bottom of a shelf prints without support
• Teardrop holes: Horizontal holes with a teardrop shape (pointed at the top) print without support. Standard in 3D print design
• Self-supporting angles: Keep all overhangs at 45 degrees or less from vertical during the design phase

Frequently Asked Questions