Designing for FDM Printing: Best Practices for Mechanical Parts

For many small businesses and hobbyists in Singapore, Fused Deposition Modelling (FDM) is the most accessible and cost-effective way to produce functional parts like brackets, gears, housings, and enclosures. Whether you're prototyping a new product or creating a custom part for a project, designing specifically for FDM printing is essential to ensure that the final print is accurate, strong, and easy to assemble.

In this guide, we’ll share the best practices we use at our 3D design and print studio—based right here in Singapore—to help local clients create mechanical parts that are ready for real-world use.

What is FDM Printing?

FDM (Fused Deposition Modelling) is a layer-by-layer additive manufacturing method. A thermoplastic filament is melted and extruded through a heated nozzle to build a part one layer at a time. FDM is ideal for mechanical parts because of its:

• Affordability

• Speed

• Material availability (e.g., PLA, PETG, ABS)

However, FDM parts are anisotropic—meaning strength varies by direction—so the design matters!

1. Orientation for Strength and Accuracy

Orientation affects how strong your part will be. Because each layer is fused to the one below it, the strength is weakest between layers. If you expect your part to bear load or stress, orient the part so that stress is aligned perpendicular to the layers.

Example: A bracket mounted on a wall should be printed vertically so that the layers resist the bending force rather than shear apart.

2. Support Structures

FDM printers can’t print in mid-air, so overhangs greater than 45° need supports. But supports increase print time and post-processing effort.

Design Tips:

• Add fillets to reduce steep overhangs

• Split complex parts into sections

• Avoid unnecessary voids that are hard to clean

We often help customers redesign parts to minimise supports and make removal easier—especially important for mechanical interfaces.

3. Tolerances and Clearances

FDM printers typically offer tolerances of ±0.2 mm, depending on calibration and material. If you’re designing mating or interlocking parts, you’ll need clearance.

Recommended:

• 0.2–0.4 mm clearance for press fits

• 0.5 mm or more for sliding/rotating parts

Clients creating housings or joints benefit from our experience in adjusting tolerances for their specific application.

4. Wall Thickness

Thin walls may warp or fail, while overly thick walls waste material and time.

Best Practice:

• Minimum: 1.5–2 mm

• Increase thickness for stress-bearing parts

We optimise designs for balance—durability without excess material—especially for enclosures and brackets.

5. Draft Angles

Parts with vertical walls and cavities can be hard to remove cleanly from the build plate. A slight draft angle (1–2°) helps reduce adhesion issues.

This is especially useful for snap-fit designs or internal features like cable channels in enclosures.

6. Hole Design

Small holes may close up during printing, and horizontally printed holes can ovalise.

Design Tips:

• Use 1.5 mm or larger diameters

• Print holes vertically when possible

• Consider post-drilling if precision is critical

We routinely adjust hole sizing and placement to save our clients time on post-processing.

7. Material Considerations

Different filaments behave differently. PLA prints easily and has good stiffness, but is brittle. PETG is more flexible and chemically resistant, while ABS can handle higher temperatures but tends to warp.

Not sure which material suits your application? Check out our material blog series or contact us for tailored advice.

8. Post-Processing Matters

Common post-processing includes:

• Sanding

• Heat treatment

• Painting

Good design reduces the need for post-processing. For example:

• Avoid hard-to-reach supports

• Keep surfaces accessible for smoothing

Our team uses design techniques to reduce finishing work and enhance aesthetics—ideal for prototypes and end-use parts.

Why Work With a Local 3D Design & Print Partner?

We’re a small, independent 3D printing business in Singapore, and we’ve worked with countless local SMEs and hobbyists to bring their ideas to life. When you commission a project with us, you get:

• Expert 3D design using Fusion 360

• Tailored recommendations based on your part’s function

• Hands-on support from design to delivery

• Reliable communication and quick turnaround

Ready to get started? Visit our website or contact us today to discuss your project—we’ll help you design smarter and print better!