In your 3D printing experience, you might have come across a poor surface just above the supports in your 3D prints. I’ve definitely experienced it, so I set out to find out how exactly to fix this issue.
You should decrease your layer height and nozzle diameter for a better foundation in your supports. Adjust your speed and temperature settings to improve overhang performance, which helps in reducing rough surfaces above supports. Improve your cooling, as well as support roof settings and look towards better part orientation.
There are many different solutions and in-depth details on how to fix a poor or rough surface above 3D printed supports, so keep reading on to best solve this ongoing issue.
Why Do I Have a Rough Surface Above My Supports?
The usual reason why you have a rough surface above your supports is due to the overhang performance of your 3D printer, or just the way the model is structured in general.
If you have a bad model structure, it’s difficult to reduce rough surfaces above supports because there just isn’t an efficient way to smooth 3D print the object.
If the part orientation is poor, you can definitely discover rough surfaces above support structures.
Overhang performance can definitely help out in terms of this issue because when your layers don’t adhere properly, they can’t produce that smooth surface that you are looking for.
It’s hard to avoid supports for complex models so you just have to make do, however, we can still find ways to make smooth surfaces above supports in one way or another.
In all honesty, with some models you can’t completely cure these rough surfaces but there are techniques and workarounds where you can alter a number of settings, the orientation and much more to solve the issue.
Before we can do this, it’s a good idea to know the direct causes behind why this might happen.
- Layer height too high
- Fast printing speeds
- High temperature settings
- Z-distance setting not adjusted
- Bad model orientation
- Bad support settings
- Low quality filament
- Poor cooling on parts
How Do I Fix a Rough Surface above My Supports?
1. Lower the Layer Height
Lowering your layer height is one of the main fixes that will help fix rough surfaces above your supports. The reason for this is related to the overhang performance, where Your dimensional accuracy increases quite a bit the lower your layer height it, and this directly translates to better overhangs.
Since you are printing more layers, the extruded plastic has more of a foundation to build up from, which is your 3D printer creating smaller steps to create that overhang in the first place.
You want to avoid having to use supports in the first place, but if you do have to implement them, you want to make them as efficient as possible. You want to have support structures for overhangs above that 45° mark, especially at a layer height of 0.2mm
If you use a layer height of 0.1mm, your overhangs can reach further and may even stretch out to that 60° mark.
That’s why I want you to have support structures for any overhang that is above 45 degrees. At this point, you can use a layer height of 0.2mm.
So to achieve better surfaces above your supports:
- Improve your overhang performance to reduce supports
- Use a lower layer height
- Use a smaller nozzle diameter
By doing this, you will be getting different advantages, that are:
- Reducing your print time
- The number of support structures will also be reduced for the print so material is saved
- Achieve a smoother surface on the underside parts.
This is how you can achieve a smooth surface on the parts above supports.
2. Reduce Your Printing Speed
This solution also relates to that overhang performance where you want your layers to adhere to each other as best as they can. When you use fast printing speeds, the extruded material can have a little trouble setting properly.
- Reduce your printing speed in 10mm/s increments until the problem is solved
- You can specifically slow down the speed of the supports rather than all speeds.
- There is ‘Support Speed’ and ‘Support Infill Speed’ which is usually half of your printing speed
This should help out in reduces the rough surfaces above supports by creating a more accurate model according to the dimensions rather than bad printing abilities.
3. Decrease Your Printing Temperature
Depending on whether you have already dialed in your printing temperature, sometimes you might be using a temperature that’s a little too high. If the filament is being melted past the necessary heat levels, it can cause the filament to be more runny.
This can easily result in sagging and drooping while printing those overhangs, which leads to rough surfaces above your support structures.
- Optimize your printing temperature by running a few tests
- Use a temperature low enough to not give under-extrusion and still print consistently.
4. Adjust Support Z-Distance Setting
The right settings can make the world of a difference in your 3D prints. The video below goes through some Cura support settings that you can implement to improve your 3D print quality.
The ‘Support Z-Distance’ setting in Cura is defined as the distance from the top/bottom of the support structure to the print. It’s a gap that provides clearance to remove supports after you have printed your model.
It’s usually at a value which is a multiple of your layer height, where mine is currently showing a multiple of two, which is actually a little much.
- You can narrow down the setting to ‘Support Top Distance’ in Cura and set it to the same as your layer height.
- A multiple of one should produce better surfaces above supports than a multiple of two.
The problem here though, is it may be harder to remove the supports afterwards, since the material can bond like a wall.
5. Split Your Model in Half
Instead of requiring the supports in the first place, you can split your model in half and put the two halves face down on your print bed. After they have printed, you can carefully glue the pieces together to form a nice bond.
Many users choose this option and it works out pretty well, but it works well for some models and not others.
The nature of supports means that you can’t get the same surface quality as the rest of your model because the material can’t be squished down as required to give a smooth surface.
If you manage to slice your model in a certain way, you can reduce the ‘scarring’ or rough surfaces above your supports, by reducing the number of supports and improving the angles that you are printing at.
6. Adjust Support (Infill) Roof Settings
There are a list of settings in Cura which relate to the ‘Roof’ of your supports which is the related to that rough surface above your supports. If you adjust these settings correctly, you can improve the support itself, as well as the surface. Rather than change the setting of the whole support, we can work towards just adjust the settings of the top of the support,
- Do some trial and testing on support roof settings
- ‘Enable Support Roof’ generates a dense slab of material between the top of the model and the support
- Increasing ‘Support Roof Density’ can improve overhang performance and fix those rough surfaces
- If you still notice sagging in the parts above your supports, you can increase it more
- You can also change the ‘Support Roof Pattern’ to Lines (recommended), Grid (default), Triangles, Concentric or Zig Zag
- Adjust the ‘Support Join Distance’ – which is the maximum distance between support structures in the X/Y directions.
- If separate structures are closer together than the set distance, they merge into one support structure. (Default is 2.0mm)
The default Support Roof Density setting in Cura is 33.33% so you can increase this value and note the changes in performance to see if it helps out. In order to find these settings you can either search it in the search bar, or adjust your Cura view to show ‘Expert’ settings.
7. Use a Second Extruder/Material for Supports (If Available)
Most people don’t have this option, but if you have dual extruders, it can help out greatly when printing with supports. You can 3D print with two different materials, one being the main material for the model, and the other being your support material.
The support material is usually one that can break away easily or even be dissolved in a liquid solution or just plain water. The common example here is 3D printer users 3D printing with PLA and using PVA for supports which is dissolvable in water.
The materials won’t bond together and you’ll have better success printing models with less rough surfaces above the support.
These two materials won’t bond together, and you will get a better chance of printing the material with the less rough surface above supports.
8. Use High Quality Filament
Low quality filament can definitely stunt your printing quality in a way that just works against getting successful prints.
Things like low tolerance accuracy, poor manufacturing methods, moisture absorbed within the filament, dust and other factors can contribute to getting those rough surfaces above supports.
- Start using high quality filament from trusted brand names with many exceptional reviews
- Amazon is a great place to start, but separate retailers like MatterHackers or PrusaFilament have great products
- Order a number of highly rated filaments and find the one which words best for your projects.
9. Improve Your Cooling
When you improve your cooling system, you can improve your overhang performance significantly. What this does is harden your melted plastic a lot quicker, giving it the ability to create a more sturdy foundation and build on top of that.
It may not be perfect, but good cooling can definitely help out with poor surfaces above supports.
- Implement the Petsfang Duct (Thingiverse) on your 3D printer
- Get higher quality fans on your 3D printer
10. Post-Print Work
Most of the solutions here are talking about adjusting the printing process so you no longer get the rough patches on surfaces above supports, but this one is about after the print is finished.
There are methods you can implement to smooth over those rough surfaces so you can have a good-looking 3D print.
- You can sand the surface using high-grit sandpaper and really make that surface smooth, inexpensively.
- If there isn’t much material left to really sand down, you can use a 3D pen to extrude extra filament on the surface
- After the filament has been attached, you can then sand it down to make the model look nice