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Gaps in Print Surfaces

· 4 min read
Pranav G.
Pranav G.

Gaps in Print surfaces​

What Is It?​

Often 3D prints can have small visible gaps on their top surfaces, outer walls, and between the infill structure and the inner walls. These cavities ruin the appearance of your 3D-printed model and might also affect its structural integrity. Often, the cause behind gaps in your 3D prints is related to slicer settings, and you can quickly resolve these gaps by fine-tuning specific settings.

What to Check?​

  • Print Speed
  • Infill settings
  • Top and Bottom layer settings
  • Extrusion issues, if any

How to Fix it?​

When printing at high speeds, you're likely to experience extrusion issues, as the nozzle is moving too fast relative to the extrusion rate. This will create gaps in the print layers as less material flows out of the nozzle. Additionally, the extruded material doesn't have enough time to bond with the adjacent walls and previous layers, leading to more gaps.

The best solution is to slightly reduce the printing speed by 5-10 mm/s till there are no gaps in your print. A slower speed gives the filament sufficient time to bond with adjacent perimeters, thus filling in the gaps in your model. This solution applies to infill speeds, wall speeds, and top and bottom layer speeds.

Increase Infill Density​

Infill acts as the foundation for the top layers of your model. A lower infill percentage leads to more gaps in the prints and doesn't create a dense enough base for the upper layers. It causes the upper layers to sag, resulting in wide, visible air gaps between the infill and the top layers.

If you're noticing gaps in your top layers, try increasing the infill density to 30-40%. This range should support the top layers and noticeably reduce any gaps in your 3D prints.

Increase the number of Bottom and Top Layers​

The bottom and Top layers are the visible walls of your 3D prints and conceal the hollowness of the model. If you use a single or two top layers in your print, they might not close off the top section, leading to visible gaps and infill of the 3D print. Similarly, if your bottom layer count is less, there might be visible cavities in the underbelly of your model.

A higher top and bottom layer count ensures that the 3D print is neatly closed off and the internal cavity of the model is not visible. An ideal value of 4-6 bottom and top layers should fill any gaps; however, you can increase this number if you use a low layer height.

The idea here is to seal the 3D prints from the top and bottom properly and ensure that you aren't able to see the very first top layer or the very last bottom layer. The outermost visible layers must be even and conceal any cavities of the previous layers.

Check for Under extrusion issues​

Gaps in print surfaces are a standard indicator of Under extrusion. If none of the above solutions work for you, there are high chances you're experiencing under extrusion in your 3D prints.

Under extrusion is a broad topic in itself, and there can be several causes behind it. You can refer to our detailed guide on under extrusion and eliminate the gaps in your prints.

Additionally, you can use tools like Obico and Octoprint to monitor your 3D prints via a connected camera remotely and quickly diagnose extrusion-related issues. These software aid in the early detection of 3D printing failures and will help you save your printing time and filament material.