HOW TO FIX OVER-EXTRUSION IN 3D PRINTING

Over-extrusion happens when the printer pushes out more filament than needed. This causes blobs on the surface, dimensional inaccuracy (parts are slightly too large), rough or bumpy walls, and filament oozing at the seam. It's the opposite of under-extrusion and is usually easier to fix.

The most common causes are: • Flow rate / extrusion multiplier too high — Set above 100% without calibration. • E-steps over-calibrated — The firmware is commanding too many steps per mm of filament. • Incorrect filament diameter in slicer — If the slicer thinks the filament is 1.65 mm but it's actually 1.75 mm, it over-extrudes to compensate. • Temperature too high — Overly fluid filament flows more than intended. • Printing too slow — At very slow speeds, excess heat builds up and the filament becomes more fluid.

Calibrate your e-steps first. Mark 100 mm on the filament, extrude 100 mm, and verify. If the extruder pushes more than 100 mm, lower the steps/mm value. Reduce flow rate in 2% increments. Print a single-wall cube (no infill, one wall) and measure the wall thickness with calipers. It should match your line width setting. Verify filament diameter: measure your filament with calipers in several spots and enter the average in your slicer settings. 1.75 mm is nominal, but actual can range from 1.72–1.78. Lower nozzle temperature by 5°C. Less heat means less flow. If you're printing very slowly (<30 mm/s), try increasing speed. The longer dwell time at low speeds causes more heat transfer to the filament.

Always calibrate e-steps before tuning flow rate. Measure filament diameter and enter it in your slicer. Print flow calibration cubes when switching filament brands. Keep your default flow rate at 100% and only adjust after calibration.