How to Fix Elephant Foot on Bambu Lab Printers

Elephant foot is the bulge around the very bottom of a print, where the first layers flare outward past the intended outline. It ruins dimensional accuracy — parts don't fit, holes near the base are too tight — and it has two causes: squish and heat.

Why the bottom bulges

Two things push the first layers outward. First, the nozzle deliberately squishes layer one into the plate for adhesion, which widens it. Second, a warm bed keeps the bottom few millimetres of plastic soft, and the weight of everything printed above slowly squeezes that soft base outward. PLA is especially prone because it softens at only about 45 °C — barely under a typical 55 °C bed.

Quick fixes

Advanced tuning

• The permanent fix lives in CAD: add a small chamfer (about 0.2 mm) to every bottom edge of the model. The chamfer absorbs the flare, and the part comes out dimensionally true no matter what the first layer does.
• Watch the bed temperature ceiling for PLA. PLA’s softening point is ~45 °C; Bambu’s default PEI bed temperature is 55 °C, which is fine, but beds run at 65–70 °C keep the base rubbery for the whole print — elephant foot plus sagging bottom corners. PLA does not need a hot bed to stick.
• PETG stays soft near the plate too (it softens around 60 °C, and its beds run 70–80 °C). A 5 °C first-layer reduction is usually enough; don’t chase it further at the cost of adhesion.
• Only the very first layer flared, and sharply? That is pure squish — compensation handles it. A bulge that fades over the bottom 2–5 mm is heat — temperature handles it. Looking closely at the shape tells you which lever to pull.
• Don’t overshoot the compensation. Values much past 0.3 mm start carving visible steps into the bottom edge and shave away real first-layer contact area, which costs adhesion on small parts. If 0.3 mm isn’t enough, the remaining bulge is thermal — go after bed temperature instead of more compensation.

Measure it, don’t eyeball it

Elephant foot is easy to quantify, which makes it easy to tune away precisely. Print a small calibration cube, then measure its width with calipers twice: once at the very bottom edge and once a centimetre up. The difference is your flare. If the bottom measures 0.25 mm wider, raising compensation by roughly half that (it applies per side) should land you at dimensionally true — one test print confirms it. Repeat only if the material or plate temperature changes substantially, because the flare is a function of squish and heat, not of the model.

This matters most on parts that mate with other parts: boxes and lids, brackets with bolt holes near the base, snap-fit enclosures. A 0.2 mm flare per side is enough to make a lid bind. For purely decorative prints, you can also just ignore it or knock the edge down with a deburring tool — but a one-time compensation bump plus a CAD chamfer removes it from every future print, which beats sanding every time.