Holes on Top Layers
|All troubleshooting pages are a work in progress.|
Holes can sometimes appear at the top of your print. Occasionally you might see a "pillowing" effect, where tracks drawn across the top of your model bend upwards and break, forming those holes.
The top of your print is where the solid shell is printed around the part’s infill. The first few layers of the shell need to bridge across the infill and support the final layers that you’ll actually see on the outside of the print. Each successive layer will print a little flatter and a little more uniformly as the bridging is compensated for. If your shells are too thin there won’t be enough layers of solid fill to achieve the perfect surface you’re aiming for. Similarly, if your HotEnd is under extruding (either due to slicing settings or a hardware problem) your top layers won’t come out cleanly.
The tracks in the top layers of your print need to merge together to form the solid surface that you expect from your prints. When the outer shell first starts to print, it has to bridge between the infill lines, and doesn’t have full support underneath it. The first top layers won’t look perfect because they’re not fully supported, and so the tracks won’t squish together and merge. With more top layers (as a result of a thicker shell) you’ll have more solid layers supporting the final perimeter layer. As a result the final perimeter layer will be perfectly supported and the tracks will merge just right.
If all the tracks of the top layers are too thin (because they’re being under-extruded) they won’t mesh together well. Increasing the overall extrusion rate of your print will help the individual tracks mesh together better.
The remaining fixes for extrusion-related issues are hardware focused. Make sure that your printer isn’t under-extruding because of a partial clog in your nozzle. Also check to see if your extruder motor is skipping backwards or perhaps grinding into your filament, as both can be signs of problems pushing filament.