Support Structures and Organic

Theoretical Background & Mechanics of Overhangs & Support Structures

In FDM (Fused Deposition Modeling) 3D printing, plastic is extruded in a molten state and relies on the underlying layer for mechanical support. When a feature extends outward without a layer directly underneath it, this is called an overhang.

The standard engineering guideline is the $45^{\circ }$ rule: overhang angles less than $45^{\circ }$ relative to the vertical axis can usually be printed without support because each new perimeter line overlaps at least $50\%$ with the previous line. However, once the overhang angle exceeds $45^{\circ }$, the overlap decreases, and printing in "free air" becomes necessary.