The underside of angled sections sags, curls upward, or looks rough and stringy. The defects appear on surfaces angled away from vertical — the shallower the angle from horizontal, the worse the result.
Understand the Angle Convention
Overhang angle is measured from the vertical (not from the horizontal). A 45° overhang has half the layer unsupported. A 60° overhang (steeper) has most of the layer unsupported. Most printers handle 45° cleanly with good cooling; 50° is harder; 60°+ usually needs supports or post-processing.
The Real Variable Is Cooling Capacity
Two identical printers printing the same file will have dramatically different overhang limits based purely on part cooling fan performance. A printer with a 5015 dual-blower setup can handle 55–60° overhangs cleanly. A printer with a single 4010 fan may struggle past 45°.
Before adjusting any settings, turn the fan to 100% and test your printer’s actual overhang limit with an overhang test print. That number is your real baseline.
Exception: ABS and ASA. These materials can’t use high fan speeds (causes delamination). For ABS/ASA, overhangs over 40° almost always need supports.
Fix Sequence
1. Maximize cooling. 100% fan speed on overhang layers. If your slicer has “overhang fan speed boost,” enable it. If you’re already at 100% and still seeing problems, the fan hardware may need upgrading.
2. Reduce overhang print speed to 15–25mm/s. Slower speed gives each deposited line more time to cool before the next line lands on top of it. Most slicers have an “overhang speed” setting under advanced/experimental settings. Setting it to 25mm/s often adds only seconds to print time on small areas.
3. Lower nozzle temperature 5–10°C for the overhang sections. Some slicers (OrcaSlicer, PrusaSlicer with specific features) allow per-feature temperatures. Lower temperature means faster solidification on the deposited line. Don’t go below your material minimum.
4. Reorient the model if possible. Rotating the part 45° or splitting it into two pieces can eliminate steep overhangs entirely. For consumer parts where appearance matters more than monolithic construction, splitting and gluing is faster than fighting overhang physics.
5. Add supports for anything over 55°. Bridge supports (supports only under bridging sections), tree supports (less contact with the part surface), or interface layers with different support settings reduce cleanup time.
What Makes Overhangs Worse
Printing in an enclosure without extra cooling provision — the hot chamber keeps deposited filament soft longer. Layer height above 0.2mm — thicker layers have more mass and gravity wins. High print temperature and high print speed simultaneously — both independently hurt overhangs, together they compound.