General Best Practices for 3D Printing Design

Different 3D printing processes have their own unique design requirements, strengths, and limitations, depending on how the part is built with each specific process. Our guide covers specific parameters for MBJ, MJF, SLS, FDM, SLA, Polyjet, Carbon DLS, DMLS, with deeper dives into each process and part feature in later sections. However, there are some general best practices that apply across all 3D printing methods, which we would like to cover in this section. By adhering to these best practices, you can significantly enhance the quality, efficiency, and durability of your printed parts.

Keep Minimum Wall Thickness in Mind

Minimum wall thickness is the smallest dimension a structure can have while still maintaining its intended strength and functionality. Below are the wall thickness requirements for different types of features to ensure structural integrity:

• Self-supporting structures (e.g., X-, T-, O-, or C-like shapes): 1.00 mm (.039”).
• Unsupported or load-bearing features (e.g., pins, tabs, or similar shapes): 1.50 mm (.059”).

Design With Even Wall Thickness

3D printed parts share many design considerations with injection molding, particularly the importance of uniform wall thickness. Maintaining uniform wall thickness helps reduce thermal deviations that occur between areas of varying thickness, which can lead to uneven cooling, warping, or dimensional inaccuracies. To add strength without increasing overall thickness, consider adding ribs, coring, or lattice structures.

Adding ribs to increase parts strength instead of changing wall thickness

Adding coring to increase parts’ strength instead of increasing thickness.

An exception to this is fused deposition modeling (FDM), where infill patterns can be adjusted to create sparse, lattice-like cross sections, offering similar structural benefits.

Provide Clearance Between Moving Features

The gap between print-in-place assembly features is crucial to prevent components from fusing together during printing and to ensure smooth movement or separation between components.

To maintain functionality, a minimum clearance of 0.70 mm (.028”) should be designed.

Remove Confined Hollows

Most commercial 3D printing processes will have trapped material or support structure in confined hollows. Line-of-sight access to clean or drain these areas is necessary. These access areas are often called “escape holes,” because they allow for material to escape during post processing.

Any cavity with a depth beyond 50.80 mm (2”) with only one access point, such as a boss, may require multiple escape holes for cleaning. We recommend making escape holes at least 5 mm (.196”) in diameter.

Fillet Everything

Fillets, or rounded internal and external corners, are preferred in every 3D printing process to mitigate transitions between features and reduce acute stress points. Generous filleting can increase the end-use performance of a printed part.

Be Mindful of Cantilevers

3D printing offers significant freedom in design, but features like cantilevers and “lollipop heads” tend to be more fragile compared to the rest of the part. Careful consideration is required when designing these elements, particularly if they are crucial to the part’s functionality.

In some cases, it is advisable to make these features replaceable or use off-the-shelf pins, especially for large parts where they risk being crushed or damaged by the part’s weight.