Home / Holes and Gaps in Solid Layers

To save plastic and printing time, most 3D printed parts are created to have a porous, partially hollow interior with a solid shell. Each top solid layer contains perimeters and infill. The perimeters trace the outline of your part creating a strong and accurate exterior. The infill is printed inside of these perimeters to form a solid layer. For the solid shell, ideaMaker allows you to specify how many solid layers you want on the top and bottom and the top of your part. For example, if you were printing a simple cube with 5 top and bottom solid layers, the software would print 5 completely solid layers at the top and bottom of the print, but everything else in the middle would be printed as a partially hollow layer (the infill percentage you set will determine how much of the interior is filled). This technique will help to use as little as possible time and material to create very strong parts. However, you may notice that the top solid layers of your print are not completely solid and having gaps and holes, depending on which settings you use.

If you have encountered this issue, please check the following things to solve the problem.

  • Not enough top solid layers

The first setting to adjust is the number of top solid layers that are used. Because of the partially hollow infill, the first solid top layer has to span across the hollow air pockets of your infill. When this happens, the extrusions for the solid layer have a tendency to droop or sag down into the empty space in between the infill. Because of this, you generally want to print several solid layers at the top of your print to ensure a nice flat, completely solid surface. The first thing you can try is to increase the number of top solid layers if you notice this problem. The additional solid layers will not add size to the exterior of your part, but take more space from the interior. You can adjust the solid layer settings by clicking “Advance” and selecting the Infill tab. Then you can edit the “Top Solid Fill Layers”

  • Fill density is too low

Lower infill density means there is more empty space in the interior and bigger gap in between. Then, the solid layers at the top of your part will have to span over bigger gaps. For an extreme case, if you are using a fill density of 0%, the entire interior of your part is hollow, and this will create a big gap that the solid layers would need to print on top of. On the other extreme case, if you are using a fill density of 100%, the entire interior of your part is solid, and this will not create any gap at all. Generally, higher infill density will provide a much better foundation for the solid layers at the top of your print. However, higher infill density will cost more material and time. If you still have this problem after increasing numbers of top solid layers, you can try to increase the infill density.

  • Under-Extrusion

If you have tried increasing the fill density and the number of top solid layers, yet you are still seeing gaps in the tops of your print, then you likely have an under-extrusion issue. This means that your nozzle is not extruding as much plastic as the software expects. For a full description of this issue and how to correct it, please read the Not Extruding Enough Plastic section.

  • Printing too fast

The infill for your part is generally printed much faster than the outlines. However, if the infill is printed too fast, it will not have enough time to bond to the outline perimeters. If you have tried increasing the infill overlap, but you are still seeing gaps between your perimeters and infill, then you should try decreasing the print speed. To do this, click “Advance” and select the Layer tab. Adjust the “Default Printing Speed”, which controls the speed of any movements where the extruder is actively extruding plastic. For example, if you were previously printing at 60 mm/s, try decreasing that value by 20% to see if the gaps between your perimeters and infill disappear. Then adjust the ‘Default Printing Speed’ again regarding to the results you get till reach best results.