How to Design Parts That Don't Need Supports

Support material is the necessary evil of 3D printing. It holds up overhangs and bridges while your part prints, then you break it off and spend time cleaning up the marks it leaves behind. Every experienced maker has the same thought: what if I just designed the part so it didn't need supports in the first place?

Good news—you absolutely can. With some thoughtful design decisions, you can eliminate supports entirely on many parts, or at least minimize them dramatically. Here's how.

Why Supports Are Worth Avoiding

Before diving into techniques, let's be clear about what supports actually cost you:

• Material waste: Supports can use 20-50% extra filament depending on the geometry
• Print time: Every support structure adds printing time—sometimes doubling it on complex parts
• Surface quality: Supported surfaces are never as clean as free-standing ones
• Post-processing: Breaking off supports and cleaning up residue takes time and skill
• Risk of damage: Removing supports from delicate features can break the part itself

On our BambuLab P1S printers, support removal is manageable, but even "easy" supports are harder than no supports at all. Every print without supports is a cleaner, faster, more reliable print.

The 45-Degree Rule: Your Fundamental Guide

The single most important concept for support-free design is the 45-degree rule. Here's why it works:

FDM printers build parts layer by layer. Each layer is offset slightly from the one below it. When a feature angles outward at 45 degrees or less from vertical, roughly 50% of each new layer overlaps with the layer below. That's enough contact for good adhesion and structural stability.

Go beyond 45 degrees, and each layer has progressively less to grab onto. At 60 degrees, you might get away with it. At 75 or 80 degrees, you're printing into thin air—and that means drooping, sagging, or outright failure.

Practical application:

• Visualize your part being printed from bottom to top
• Any surface that angles more than 45 degrees from vertical will likely need support
• Design those surfaces as 45-degree chamfers instead, and they'll self-support

Chamfers vs. Fillets: The Designer's Choice

This is one of the simplest and most powerful changes you can make to your designs.

Fillets (rounded transitions) look great on machined parts but can create support nightmares in 3D printing. A curved surface often passes through angles greater than 45 degrees as it transitions, creating overhangs that need support.

Chamfers (angled transitions) at 45 degrees are completely self-supporting. They might look slightly more industrial, but they print cleaner every time.

When to use each:

| Situation | Best Choice | |-----------|-------------| | Bottom edges of a part | 45° chamfer (no supports needed) | | Top edges of a part | Fillet is fine (overhangs face up) | | Internal corners | Fillet for strength, chamfer if the corner is on an overhang | | Aesthetic surfaces | Chamfer if it will be printed facing down |

Real example: Consider a simple mounting bracket with a curved fillet where it meets the wall. If that fillet faces downward during printing, it needs support. Replace it with a 45-degree chamfer, and it prints cleanly with nothing to remove afterward.

Teardrop Holes: The Horizontal Hole Solution

Circular holes perpendicular to the build direction (horizontal holes) are a classic support problem. The top of the circle becomes a flat overhang that can sag or collapse without support.

The solution? Teardrop-shaped holes.

A teardrop hole has a normal circular bottom but angles up to a point at the top. The angled sides (at 45 degrees) are self-supporting, eliminating the flat overhang entirely.

When to use teardrop holes:

• Holes larger than 8-10mm in diameter
• Any horizontal hole where surface finish matters
• Holes that need to accept fasteners or pins (sagging changes dimensions)

When you can skip them:

• Small holes under 8mm often bridge just fine
• Vertical holes (parallel to the print direction) don't have this problem
• Holes where you'll drill or ream to final size anyway

Flat teardrop variation: A pure teardrop wastes space above the hole. A "flat teardrop" goes up at 45 degrees from the hole's edge, then bridges across horizontally at the top. This keeps the self-supporting benefit while taking up less vertical space.

Alternative: Diamond holes. Some designers prefer diamond-shaped holes instead. All four sides are at 45 degrees, making the entire hole self-supporting from any direction. This works well for cable routing or applications where the exact shape doesn't matter.

Strategic Model Orientation

Sometimes the best design change is simply rotating your model before printing.

The bookshelf example: A bookshelf standing upright has multiple horizontal surfaces (the shelves) that all need support. Lay that same bookshelf on its back, and every shelf becomes a vertical wall—no supports anywhere.

Think about it during design:

• Which orientation puts the most complex geometry facing upward?
• Can critical surfaces touch the build plate for the smoothest finish?
• Does rotating 45 degrees on the Z-axis change which features need support?

At Mandarin3D, we evaluate print orientation for every order. But if you're designing with orientation in mind from the start, you can create parts that print beautifully in the most obvious position.

Bridging: Spanning the Gap

Bridging is when the printer draws filament across open space between two support points—like spanning a doorway with a horizontal surface.

Modern printers handle bridges surprisingly well. Our BambuLab machines can bridge 15-20mm with only minor sagging on the underside. Shorter bridges (under 10mm) often come out nearly perfect.

Design strategies for better bridges:

• Keep unsupported spans under 10mm when possible
• Add intermediate supports designed into the model (thin columns that become part of the structure)
• Use the shortest bridge direction—a 30mm bridge can become a 15mm bridge with the right orientation
• For long spans, consider adding a slight arch rather than a flat bridge

Critical point: Bridges need endpoints. A bridge from one side of an arch to the other works fine. A horizontal surface extending into space with support on only one side isn't a bridge—it's an unsupported overhang.

Splitting Models: The Two-Part Solution

When geometry simply won't cooperate, the smartest move is often splitting the model into multiple pieces that each print without supports.

Ideal split locations:

• Along flat surfaces (gives you a good glue joint)
• At natural break points in the design (seams, color changes, functional divisions)
• Where supported surfaces would be hidden after assembly anyway

Designing for assembly:

• Add registration features (pins, tabs, interlocking shapes) so parts align perfectly
• Leave flat mating surfaces for strong adhesive bonds
• Consider adding screw holes if the joint needs to be strong or removable

Split strategies:

• Vertical splits work well for tall parts with overhangs on multiple sides
• Horizontal splits help when the bottom half would need supports but the top wouldn't
• Angled splits can separate a single difficult feature from an otherwise easy print

A cup with a handle is a perfect example. Print the cup itself in one piece (easy, no supports), print the handle flat in another piece (also no supports), then glue them together. Total support material used: zero.

Built-In Support Structures

Sometimes you need supports, but you'd rather design them yourself than let the slicer generate them.

Why design your own:

• Easier removal with intentional break points
• Better placement for your specific geometry
• Can become functional parts of the design
• More material-efficient than auto-generated supports

Examples:

• A thin column under an overhang that breaks off cleanly at a designed weak point
• A lattice structure that becomes a decorative element while supporting the ceiling of an internal cavity
• Removable inserts that support overhangs, then slide out after printing

This approach works best for experienced designers, but even beginners can add a simple supporting rib or column that's easier to remove than tree supports filling an entire cavity.

Material Considerations

Different materials bridge and overhang differently:

PLA cools quickly and holds its shape well, making it excellent for aggressive overhangs and bridges. If you're pushing limits, PLA is often the most forgiving choice.

PETG is slightly more prone to sagging on overhangs but releases from supports more cleanly when you do use them. It's a good middle ground.

TPU (flexible filament) doesn't bridge well at all due to its flexibility. If you're printing TPU, design conservatively with minimal overhangs.

At Mandarin3D, we primarily print in PLA and PETG, both of which handle self-supporting geometry well. Our BambuLab P1S and H2S printers have excellent cooling systems that help maximize overhang performance.

A Support-Free Design Checklist

Before finalizing your model, run through this mental checklist:

1. Check all overhangs: Anything over 45 degrees? Can you add a chamfer?
2. Examine horizontal holes: Would teardrop or diamond shapes help?
3. Consider orientation: Is there a better way to position this on the build plate?
4. Look for bridges: Are spans short enough to print cleanly?
5. Evaluate problem areas: Would splitting the model simplify things?
6. Test the result: In your slicer, preview with supports disabled—what fails?

When Supports Are Actually the Right Choice

Let's be realistic: some designs genuinely need supports. A highly detailed figurine with outstretched arms, a precise mechanical housing with internal features, or any part where a specific surface must face downward—these might print better with supports than without.

The goal isn't to eliminate supports in every possible case. It's to eliminate unnecessary supports through thoughtful design. Use supports when they genuinely improve the result, not because you didn't think about alternatives.

Get Your Support-Free Design Printed

Designing for support-free printing becomes intuitive with practice. After a few projects, you'll naturally visualize the build direction and adjust geometry to avoid problems before they happen.

Have a design you'd like to print without supports? Upload your model to Mandarin3D, and we'll review it with support-free printing in mind. If we spot geometry that would benefit from a minor modification—a chamfer here, a different orientation there—we'll let you know before printing.

Not sure if your design needs supports or not? Send it our way. We look at every file individually and can suggest changes that might save you time and money while delivering a cleaner result.

Questions about designing for support-free printing? Reach out at orders@mandarin3d.com—we're happy to talk through your specific design challenges.