3d print problems gaps

What’s the 3D Printing Problem?

When you look at the top or bottom of the print, you can see a slight gap between the infill and the outer perimeter walls.

What’s Causing this 3D Printing Problem?

Gaps between the perimeter and top layers used to be a common problem, but as printer accuracy has improved and the support for different materials extends, it’s now less of an issue than it was.

However the new wave of advanced materials are far less forgiving than the likes of PLA and ABS, and we’re starting to see a slight resurgence of the problem.
Gaps are caused by the filament used for the infill and outer walls not quite meeting bonding and is a relatively easy fix.

The most obvious cause of the problem is that the infill overlap is not set, or it’s set to “0”. This means that the slicing software is actually telling the printer not to allow the two parts of the print to meet.

Another issue could be the order in which you have set the infill and outer perimeters to be printed. If you’re printing the perimeter first for a high quality print then there is generally little or no overlap which can again cause the problem.

3D Printer Troubleshooting: Gaps between Infill and Outer Wall

  1. Check the infill overlap. This is by far the most common issue and is really easy to resolve. In your slicing software locate the ‘Infill Overlap’ option and increase the value.
    • In Cura by default this is set to 15% so raise it to 30%.
    • In Simplify3D you’ll find the option in ‘Edit Process Settings > Infill > Outline Overlap’ again increase the value. This setting is directly linked to the extrusion width, so the % value will be a % of whatever you’re extrusion width is. When adjusting this setting always keep it below 50% or you’ll start to see the effects of the overlap in the outer perimeters of your print.
  2. Printing infill before the perimeter. If you’re printing with a relatively thin outer wall the structure of the infill can show through. If this happens then you can switch the order by which the printer lays down the infill and perimeter layers. For example, in Cura check to see if you have ‘Infill prints after perimeters’ ticked.
  3. Increase Hot end temperature. Some of the latest advanced materials such as XT-CF20 are a little less forgiving when it comes to spread due to the carbon fibres that make up part of their structure. When printing with these materials you may find that a slight 5-10º increase in hotend temperature makes all the difference.
  4. Slow it down. Okay, so you may be in a rush to get the print out, but printing at higher speeds can cause all sorts of issues if the printer isn’t perfectly calibrated. If you need to print quick you can still avoid gaps by decreasing the speed of the top layer.

3D Printing Problem Checklist: Gaps between Infill and Outer Wall

  • Check the infill overlap.
  • Printing infill before the perimeter.
  • Increase Hot end temperature.
  • Slow it down.

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3D Printing Problems #18: Non-Manifold Edges

3d print problems non manifold

3d print problems non manifold

What’s the 3D Printing Problem?

Parts of your print are missing or the final print is weak and falls apart despite the exterior quality of the print looking fine. Sections of the print look completely different from the print preview or the final print has geometry errors that make no sense.

What’s Causing this 3D Printing Problem?

Non-manifold edge are the common cause of misshapen or odd prints. Non-manifold edges are the edges of models that can only exist in the 3D space and not the physical world.

For example if you have two cubes in the real world and try to overlap them directly, it’s physically impossible as the solid outer walls prevent the two objects from intersecting.

In the 3D world you can simply intersect the two, they still exist as individual objects, but the software we use also enables them to intersect in the virtual world.

In order to get the two to print correctly the objects need to be merged so that any inner walls are removed and an object with a single undivided inner cavity is left.

Another common cause is if you have an object such as a cube and delete one of the surfaces. You essentially have an object with a hole, it might look like a shape with five sides, but it only exists in the virtual 3D space, this is geometry with no physical form.

Although you can see the outer walls in the software, the walls that meet the hole only have dimensions in two axis. The third dimension which we see as the thickness of the wall is only illustrative and has no real physical dimension. When it comes to slicing the model the  software does it’s best and in many cases will repair the hole, however in more complex models the effects can be interesting to say the least.

3D Printer Troubleshooting: Non-Manifold Edges

  1. Use latest slicer software. Most of the latest slicer engines all support the automatic fixing of non-manifold edges but it’s still good practice to ensure that your models are correctly formed and print ready.
  2. Fix in Horrible in Cura. In Cura open Expert Settings and make sure that under ‘Fix Horrible’ you have Combine everything (Type-A) ticked.
  3. Fix ‘Non-manifold’ in Silmplify3D. In edit ‘Process settings’ click the ‘Advanced’ tab and select ‘Heal’ next to ‘Non-manifold segments.
  4. Use the layer view. In your slicer software use the layer view to check through the model so you can see where the issues appear. A quick slide through the layers will often highlight an easy to fix problem.
  5. Use software to fix issues. One of the easiest ways to fix models with non-manifold edges is to use software; Blender and Meshmixer both have features built in that will quickly enable you to highlight problems with your models and fix them prior to slicing.
  6. Merge objects. Really it’s better to fix your 3D models prior to importing them into your slicing software. To do this, make sure that when you have two objects that do intersect or overlap you choose the appropriate Boolean function to either intersect, merge or subtract.

3D Printing Problem Checklist: Non-Manifold Edges

  • Keep your slicer software up to date.
  • “Fix Horrible” (in Cura).
  • Fix ‘Non-manifold’ (in Silmplify3D).
  • Use the layer view to check for mistakes.
  • Use software like Blender or Meshmixer to fix issues.
  • Merge objects.

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