Generally, when 3D printing, you want the outside surface to be as smooth as possible. The only exception to this should be patterns that you have explicitly designed. If you can see unusual patterns on the outside of your prints, you may see the infill showing through the outer shell of the print. A tell-tale sign of this issue is repeating patterns on the outer shell that align with your infill pattern.
Possible Causes for Unusual Patterns on the Outside of Prints
One cause of this issue can be the infill overlap setting being set too high. Infill overl4ap controls how much the infill material overlaps with the outer shell. A value of 15-30% is typical. However, if this value is 50% or higher, then it can start showing through, so make sure that your slicer software’s infill setting is below 50%.
Even with a normal infill overlap setting, you may still face issues if your outer shell is too thin. Try thickening the shell by simply doubling the shell thickness.
Tip: The shell thickness should be a multiple of the nozzle size. If it isn’t, the printer can’t accurately reproduce the instructions it’s given. The results of this can vary between devices as some may round down and others round up. If this setting is wrong, it can also cause a range of other issues throughout your entire print.
While you’d normally print the infill before the outer shell, if you’re facing the infill’s issue showing through, you should change this around. Your slicing software should allow you to configure the shell to print before the infill.
If the issue is noticeably stronger on one or two sides than on the others, then the issue could be down to the printer’s calibration. Go through the manufacturer’s recommended calibration process.
If you’ve completed a print and then noticed the issue, you may be able to address it with some careful sanding. This will typically mean that you need to perform further post-processing such as smoothing or painting but may save the print. This can be especially useful if the affected area is small on an otherwise large print thanks to the time and filament cost of having to print a new version.
Hopefully, these tips should help you resolve any issues you might have with the infill showing through the outer shell. If you’ve got any other tips to share to help resolve this issue, feel free to leave them down below.