Overhangs & supports

The classic guidance is “45° is fine, anything steeper needs support.” That's a useful floor, but modern slicers and well-cooled materials can comfortably hold 50-60° without supports. Anything steeper than that, measured from vertical, starts to droop, sag, or peel at the layer boundary.

Angles measured from the build plate. 70°+ overhangs almost always need support.

Cooler-running materials (PLA) hold steeper overhangs because each layer solidifies before the next one piles on. Enclosed materials (ABS, ASA, PA-CF) run hotter for layer adhesion and sag earlier.

A bridge is a flat span between two supported points — the ceiling of a slot, the underside of a window cut-out, the top of a captive-nut pocket. FDM can bridge surprisingly far in PLA because each strand is stretched taut by the moving nozzle and cooled instantly by the part fan.

The numbers in the table above are working maxima at 0.2 mm layer height. If your part has bridges longer than that, the slicer will either add supports underneath or accept a slight droop on the first bridge layer. Two design fixes work well:

• Chamfer the bridge ends with a 45° transition into the supporting walls. The bridge then starts narrower and gradually widens, which holds tension better than a square abutment.
• Split very long bridges with a thin sacrificial rib running across them. The rib clips off in seconds after the print.

• Chamfer instead of fillet on downward-facing edges. A 45° chamfer prints clean; a fillet's underside hangs unsupported.
• Split the part at a natural seam and glue or screw it together — often eliminates supports entirely and gives a better surface finish where it matters.
• Re-orient on the bed. Lying a bracket on its side often turns a 90° overhang into a manageable 30°. Tell us in checkout notes if you have a preferred orientation.
• Use teardrop or hexagonal holes for horizontal openings. Round horizontal holes need supports above the equator; teardrops don't.