Visible Line on Outer Perimeter when Transitioning from Solid Infill to Perimeter-Only Walls
Hello guys,
I have been struggling with a persistent print quality issue for about a week now, and I would like to ask for your advice.
When printing models that transition from a solid infill section (dense or top layers) to a perimeter-only wall (around 3 mm thick), a visible horizontal line or band consistently appears on the outer perimeter exactly at that transition height.
The issue is not a classic seam; it only occurs at the layer where the slicer switches from “solid infill support” to “perimeters only.”
Below the transition, the outer wall rests on solid infill and looks smooth.
Above the transition, the outer wall has no more solid infill behind it, and a clear line becomes visible on the outside.
Adjusting settings such as seam position, infill/perimeter overlap, extra perimeters, top solid layers, and even modifiers has not eliminated the problem. In some cases it became worse (the overlap pushing the perimeter outward).
We suspect this may be related to pressure changes in the hotend or slicer handling of the infill-to-perimeter handover.
I am preparing a small print farm for a product line where surface quality is critical, so finding a reliable solution is essential.
Could you please advise if there are known best practices, slicer settings, or firmware-related tuning (e.g. pressure advance/linear advance) that specifically address this infill-to-perimeter transition line issue? Any guidance would be highly appreciated.
Thank you very much in advance.
Best regards
This is a very old issue - search for 'Buldge' (yes, the OP misspelled it) for the history. The underlying cause is often related to the absolute difference between the thermal contraction of long extrusion runs against shorter ones.
where surface quality is critical,
In these cases it's always best to post process, sand fill and paint or print oversize and machine to fit; set up jigs if the dimensions are critical.
Cheerio,