The top surface is rough or has small holes
The top surface is printed over infill, which means over gaps. It is all about giving it enough support and enough solid layers to seal completely.
What the failure looks like
The final layer looks like a mesh, with small holes or separated lines, instead of a smooth, uniform surface.
Causes, most likely first
- 01
Too few top solid layers
With 2 layers, it rarely seals properly.
- 02
Infill density too low
At 10%, the top layers have to bridge large distances.
- 03
Under-extrusion
Not enough material to seal the surface.
- 04
Insufficient fan cooling
Top lines fuse poorly if they do not solidify quickly.
Step-by-step fix
1. Increase to 4-5 top solid layers
Rule of thumb: at least 0,8 mm total thickness.
2. Increase infill to 20-25%
Use a gyroid or cubic pattern, which support the top layers better.
3. Enable ironing
Passes the hot nozzle over the last layer to smooth it out. Flow 8-12%, speed 20-30 mm/s. It adds print time, but the finish is almost smooth.
4. Check the flow rate
If you have general under-extrusion, it shows here first.
5. Set the fan to 100% on top layers
Always for PLA; half speed for PETG.
So it doesn't happen again
- Use the same profile for parts that will be visible from above and check in the slicer preview that the top layer is completely filled.
Related questions
Does ironing work on PETG?
Less effectively than on PLA: PETG tends to accumulate and leave blobs. Try a low flow rate (6-8%) or skip ironing altogether.
Keep reading
What if it isn't worth your time?
Sometimes the part is more urgent than the learning curve. We're a workshop in Viladecavalls: send us the file and we'll print it with the right material and settings.
Still not working?
Tell Marco which printer and material you use and he'll tell you what to change.
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