Having gaps in the top layers of your 3D prints aren’t ideal in any circumstance, but there are solutions which you can try to solve this problem.
The best way to fix gaps in your top layers is to increase the number of top layers in your slicer settings, increase infill percentage, use a denser infill pattern, or look towards fixing under extrusion issues. Sometimes using a default slicer profile works perfectly to fix gaps in top layers.
This article will attempt to guide you through fixing this problem, so keep reading for a detailed solution.
Why Do I Have Holes & Gaps in the Top Layers of my Prints?
Gaps in prints can be a result of several errors related to the printer or the print bed. To identify the origin of the main issue you should consider overviewing some of the main parts of the 3D printer.
Below we have mentioned a few reasons which might be a reason for gaps in your 3D prints as well.
Reasons for gaps in 3D prints may include:
Adjusting number of top layers
Increase infill density
Under-extrusion, over-extrusion and extruder skipping
Fast or slow printing speed
Filament quality and diameter
Mechanical issues with a 3D printer
Clogged or worn out nozzle
Unsteady surface
Unexpected or immediate temperature changes
How to Fix Gaps in the Top Layers of my 3D Prints?
The video explains one side of having gaps in top layers, which is also known as pillowing.
To improve your printer’s performance and the output’s quality, there are several ways you can practice to do so.
Sometimes just using a default profile for your 3D printer works a treat, so definitely try that beforehand. You can also find custom profiles that other people have created online.
Now let’s get into the other solutions that have worked for other 3D printer users.
1. Adjusting Number of Top Layers
This is one effective method of getting rid of gaps in print layers. The solid layer’s extrusions tend to drop and drool in the air pocket because of your partially hollow infill.
The fix is simply changing a setting in your slicer software:
Try adding more top solid layers in your slicer
A good rule is to go by is to have at least 0.5mm of top layers in your 3D prints.
If you have a layer height of 0.1mm, then you should try to have at least 5 top layers to satisfy this guideline
Another example would be if you have a layer height of 0.3mm, then use 2 top layers which would be 0.6mm and satisfy the 0.5mm rule.
This is probably the easiest fix in the problem of holes or gaps in your 3D prints since it’s a simple setting change, and it’s very effective in tackling this problem.
If you can see infill through your top layer, then this should help significantly.
2. Increase Infill Density
Another common reason behind having holes and gaps in your 3D prints is using an infill percentage which is too low.
The reason this happens is that your infill kind of acts as supports for the higher parts of your 3D prints.
A low infill percentage would mean less support, or foundation for your material to adhere to, so it can lead to melted plastic drooping which causes those holes or gaps.
The simple fix here would be to increase your infill percentage for a better foundation on your 3D prints
If you use an infill density of around 20%, I’d try out 35-40% and see how things work out.
A setting in Cura called “Gradual Infill Steps” allows you to enable a low infill density at the bottom of your print, while increasing it for the top of the print. Each step you use means that the infill will be halved, so 40% infill with 2 steps goes from at the top 40% to 20% to 10% at the bottom.
3. Under-Extrusion and Extruder Skipping
If you are still experiencing holes or 3D printing gaps between layers or in your top layers, then you probably have under-extrusion issues, which can be caused by a few different issues.
Extrusion issues may include under-extrusion or your extruder clicking which effects the printing badly, and signals some weakness in your extrusion system.
When the amount of filament that your 3D printer thinks is going to be extruded is actually less, this under-extrusion can easily result in missing layers, small layers, gaps within your 3D print, as well as little dots or holes between your layers.
The most common fixes for under-extrusion are:
Increase printing temperature
Clean nozzle to clear any jams
Check that your nozzle isn’t worn out from several hours of 3D printing
Use better quality filament with good tolerances
Make sure your filament diameter in slicer matches actual diameter
Check flow rate and increase your extrusion multiplier (2.5% increments)
Check if the extruder motor is working properly and is provided with enough power or not.
Adjust and optimize layer heights for your stepper motor, also called ‘Magic Numbers‘
Other fixes that could help out in this instance are to make sure your filament feed and extrusion path is smooth and clear. Sometimes having a low quality hotend or nozzle just doesn’t do the best job at melting the filament adequately.
When you upgrade and replace your nozzle, the changes that you can see in 3D print quality can be quite significant, which many people have attested to.
I would also implement Capricorn PTFE tubing for a smoother filament feed into your nozzle.
4. Adjust Printing Speed to be Faster or Slower
Gaps can also occur if your print speed is too high. Due to this, your printer might find it hard to extrude filament in less time.
If your 3D printer is extruding and accelerating at the same time, it can extrude thinner layers, then as it decelerates, extruder normal layers.
To fix this issue, do try the following:
Adjust speed by increasing or decreasing the speed by 10mm/s, which can be done specifically just for top layers.
Check print speed setting for different factors like walls or infill etc.
Check for acceleration settings along with the jerk settings to avoid vibration, then decrease these also
50mm/s is considered a normal speed for your 3D printer
It allows for more cooling which lets your filament harden to form a better foundation for the next layer. You can also print a fan duct to direct cool air straight to your 3D prints.
Incorrect filament diameter can cause printing complications bringing gaps in layers. Ensure your slicer has the ideal filament diameter.
Another reliable method of ensuring this is by measuring the diameter yourself with the help of calipers that you have the correct diameter specified in the software. The most commonly found diameters are 1.75mm and 2.85mm.
The stainless-steel Kynup Digital Calipers is one of the highest rated calipers on Amazon, and for good reason. They are very accurate, up to an accuracy of 0.01mm and very user-friendly.
To keep your filament perfect for a long time, read the guide properly.
Get a filament from the best manufacturers to avoid headaches of the future.
6. Correct Mechanical Issues with the 3D printer
When it comes to machines, small or big issues may arise. However, the thing is to be aware of how to fix them. Your 3D printer may experience mechanical issues that can bring gaps in the printing. To fix it, try out the following things:
Machine oiling is necessary for smoother movements and general maintenance
Check if all parts are working properly or not
Make sure screws are not loose
Z-axis threaded rod should be placed accurately
The print bed should be stable
Check printer machine connections
The nozzle should be tightened correctly
Avoid using floating feet
7. Fix or Replace Clogged/Worn Out Nozzle
The clogged and contaminated nozzle can also significantly bring gaps in 3D Printing. So, check your nozzle and if need be, clean it for better print results.
If the nozzle of your printer is worn out, then purchase nozzle from a trusted manufacturer
Keep cleaning nozzle with proper instructions as mentioned in the guide.
8. Put Your 3D Printer on Steady Surface
An unstable or vibrating surface cannot bring the perfect print out. This surely can bring gaps in printing if the machine vibrates or is likely to get unstable because of its vibrating surface.
Fix this issue by placing the printing machine at a smooth and stable place.
9. Unexpected or Immediate Temperature Changes
Temperature fluctuations can be a great reason for your print to get gaps while printing. This is the most important issue which should be fixed immediately because it decides the flow of plastic as well.
Use a brass nozzle as it works best when it comes to thermal conductivity
Check if the PID controller is tuned or not
Keep checking that temperature should not fluctuate immediately
Check out this video by CHEP for some more helpful tips to fix gaps in your prints.
Conclusion
Gaps between the top layers of 3D print can be a result of various printer’s shortcomings we have mentioned above. There can be more reasons for these gaps, but we have mentioned the major one.
If you figure out the likely root cause, it’ll be easier to solve the error. The main thing is to read the guide thoroughly when you are going to use any printing machine if you want to bring perfection to your work.
Michael Dwamena is the founder of 3D Printerly, a platform dedicated to simplifying 3D printing for hobbyists and professionals alike. Owns over 20 3D printers (filament and resin) and has plenty experience 3D printing. Michael has authored over 900 articles, helping millions navigate the exciting world of 3D printing.
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