Why the bottom of your print is too wide (elephant's foot + 3 fixes)
Elephant's foot: the first layers are pressed into the bed for adhesion and spread out slightly. It ruins press-fits and can fuse print-in-place parts.
What you'll learn
- Elephant foot compensation on
- Don't over-squish layer one
- 0.5 mm chamfer on bottom edges
Chapters
- 0:00The mystery bulge
- 0:29Why it happens
- 0:51Why it matters
- 1:02Fix 1: the slicer
- 1:21Fix 2: the first layer
- 1:33Fix 3: the design
- 1:47Recap
Pause and guess
What causes the bulge at the bottom? (tap to see the answer)
- Wet filament
- Squished first layers on a hot bed
- Too much infill
Print settings
| Quality | |
|---|---|
| Layer height | 0.20 mm |
| First layer height | 0.20 mm |
| Elephant foot compensationkey setting | 0.15 mm |
| Strength | |
| Wall loops | 2 |
| Sparse infill density | 15 % |
| Support | |
| Enable support | Off |
| Others | |
| Brim | None |
Grouped by the tabs in Bambu Studio. Names differ slightly in PrusaSlicer and Cura. Settings not listed can stay at your printer profile.
Test it yourself
Mentioned in this episode
Full transcript
Your test cube measures perfectly. Thirty millimeters, spot on. Except right at the bottom, where it's suddenly too wide. Why?
It looks like a tiny detail. But it ruins press-fits, stops lids from sliding on, and can even weld print-in-place parts together.
Pause and guess. What causes that bulge? A: wet filament. B: squished first layers on a hot bed. Or C: too much infill?
It's B. And here's the twist: it starts on purpose.
Meet the elephant's foot. Named after the way the bottom of the print spreads out, like the foot of an elephant.
It starts on purpose. Your printer presses the first layer into the bed, a little flatter and wider than normal, so the print sticks and doesn't come loose halfway.
Then the heated bed keeps those bottom layers soft for longer, and the weight of everything printed above pushes down on them. So they spread outward, just a little.
A few tenths of a millimeter sounds like nothing. But remember our print-in-place hinge, with its 0.35 millimeter gap? A bulge at the bottom can close that gap, and the parts fuse.
Fix one, in the slicer: elephant foot compensation. It shrinks the outline of the first layer slightly inward, so the bulge ends up where the wall should be.
In Bambu Studio and PrusaSlicer it's literally called elephant foot compensation. In Cura, use a small negative initial layer horizontal expansion.
Fix two, check your first layer. If the nozzle sits too close to the bed, it squishes the plastic extra flat. And if the bed is hotter than your filament needs, the bottom stays soft too long. Both make the bulge worse.
Fix three, in the design: a small chamfer on the bottom edge, around half a millimeter at 45 degrees.
Now the bulge simply fills the chamfer, instead of sticking out. This works on every printer and every slicer, because it's built into the part itself.
In short: turn on elephant foot compensation, don't over-squish your first layer, and chamfer the bottom edges of parts that need to fit.
Grab this chamfered test cube for free and measure it yourself. Link in the description. I'm Spoolbert, see you in the next one.
Spoolbert explains one 3D printing problem per episode, with a free model to test the fix. Made by EMBODY³, a 3D printing studio in Belgium.