What elephant foot is and how to confirm it
Elephant foot is a bulge at the very bottom of a print. The first layer is meant to be squished a bit for adhesion, and the heated bed keeps the bottom layers soft for a while. When the squish is too heavy or the plastic stays too soft, it spreads outward and the layers above push down on it. The result is a lip around the base that is wider than the walls.
Confirm it by measuring the part with calipers at the base and a few millimeters higher. A difference of 0.2 mm or more at the bottom is typical elephant foot. It matters most for parts that must fit into holes or slide against each other, and for holes in the bottom face, which come out smaller.
Causes, most likely first
- Z-offset too low. The nozzle presses the first layer too flat and wide.
- Bed too hot. Lower layers stay soft and sag under the weight above.
- First-layer flow or width too high. Some profiles use 110 to 120 percent first-layer flow or wide first-layer lines.
- Heavy or tall parts pressing down on warm lower layers.
- No slicer compensation for the expected spread.
Fixes, cheapest and fastest first
1. Raise the Z-offset slightly
Raise the nozzle in small steps, about 0.02 to 0.05 mm at a time. The first layer should still show flat lines that touch each other with no gaps, but should not look smeared or translucent with ridges pushed up between lines. Recheck adhesion after each change.
2. Lower the bed temperature
Drop the bed 5 °C at a time. For PLA, 50 to 60 °C is often enough on PEI. Some slicers let you keep a hotter first layer for grip and reduce the bed for later layers.
3. Check first-layer flow and line width
Set first-layer flow to 100 percent if it is higher. A first-layer line width of about 100 to 120 percent of the nozzle diameter is reasonable; much wider than that adds spread.
4. Use slicer compensation
Many slicers have a setting called elephant foot compensation or initial layer horizontal expansion. Set it to a negative value around 0.1 to 0.2 mm to shrink the first layer outline. Measure and adjust.
5. Add a chamfer to the model
A 0.5 mm by 45 degree chamfer on the bottom edges hides the remaining bulge. This is common practice for parts that need clean edges.
6. Add cooling after the first layers
Bring the part cooling fan up by layer 2 to 4 for PLA so the lower layers firm up sooner.
Material notes
- PLA: the most common case because PLA softens at a fairly low temperature. Keep the bed modest and the fan on early.
- PETG: tends to be printed with a slightly higher Z-offset anyway because it sticks too hard when squished; that also limits elephant foot.
- ABS: needs a hot bed, so rely more on slicer compensation and chamfers than on a cooler bed.
- TPU: soft and compressible; a light first-layer squish and modest bed temperature, around 40 to 60 °C, keep it in check.
Prevention checklist
- Recheck the Z-offset after changing the nozzle or build plate.
- Use the lowest bed temperature that still holds the part reliably.
- Keep first-layer flow at 100 percent.
- Enable elephant foot compensation in your printer profile.
- Design bottom chamfers on precision parts.
- Measure a calibration cube base occasionally to catch drift.