Learning how to improve overhangs in your 3D prints is a skill that your print quality will really appreciate. I’ve had some pretty poor overhangs in the past, so I decided to set out and figure out the best methods to improve them. It actually isn’t as hard as I thought.
To improve overhangs you should improve your cooling with a fan upgrade and fan duct to direct cool air to melted filament. Reducing model angles to be 45° or less is a great way to reduce bad overhangs. You can also decrease layer height, printing speed and printing temperature so filament isn’t as melted, allowing it to cool quicker.
This is a good starting point to improve overhangs. The rest of this article goes into some pretty key details to help you understand the problem and how each method assists in improving your overhang (with videos), so keep reading to find out more.
What Are Overhangs in 3D Printing?
Overhangs in 3D printing are where the filament your nozzle extrudes ‘hangs over’ the previous layer too far, to a point where it is in mid-air and cannot be adequately supported. This results in that extruded layer ‘overhanging’ and producing poor print quality, since it cannot form a good foundation underneath.
A good overhang is one where you can actually 3D print at an angle above the 45° mark which is diagonal angle. To put this into perspective, you can picture the letter T trying to be 3D printed.
You would do fine up to the middle part of the letter because it is nicely supported, but when you get to the top line, this 90° angle is far too sharp to have any support underneath.
That is what we call overhang.
There are overhang tests which you can try which have angles going anywhere from 10° up to 80° to see just how well your 3D printer handles overhangs, and they can perform pretty well as long as you take the right steps.
The most popular overhang test on Thingiverse is the Mini All in One 3D Printer Test by majda107, which tests several important features on a 3D printer. It is printed with no supports and 100% infill to really test your printer’s abilities.
Its difficult to print overhangs at sharp angles because there isn’t enough of a supporting surface below your next extruded layer for it to stay in place. It will practically be printing in mid-air.
In 3D printing, the general rule to combat overhangs is to print angles that at 45° or less, where angles above this will start to be negatively affected by overhang.
The physics behind this angle is that, when you picture a 45° angle, it is right in the middle of a 90° angle, meaning that 50% of the layer is support, and 50% of the layer is unsupported.
Going past that 50% point really outweighs the support needed for a solid enough foundation, and the further out the angle, the worse. You want your layers to have more surface area to have adhesion for successful, strong 3D prints.
Some models are complex, making it pretty hard to avoid overhangs in the first place.
Luckily, there are many methods to improve just how much overhang our 3D printers can deliver, so stay tuned to find out these tips and tricks.
How To Improve Overhangs in Your 3D Prints
As previously mentioned, making sure your models don’t have angles higher than 45° is a great solution to overhangs, but there are a lot more ways to improve overhangs that you can be implementing in your 3D printing.
It isn’t always possible to eliminate those angles, so let’s get into the good stuff.
1. Increase Fan Cooling of Parts
The first thing I would do to improve my overhangs is increase the efficiency of my layer cooling. This comes down to either replacing the fan for a higher quality one, or using a fan duct which properly directs the cool air to your 3D prints.
Many times, your 3D prints will be cooled on one side, while the other side is struggling with overhangs because it doesn’t have adequate cooling. If this is your situation, you can correct the problem pretty easily.
The reason fans and cooling works so well is because, as soon as the material is extruded through the nozzle, it gets cooled to a temperature well below the melting temperature, leaving it to quickly harden.
The hardening of your filament as it get extruded means it can build a good foundation regardless of little support underneath. It’s similar to bridges, which is extruded lines of material between two raised points.
If you can get good bridges, you can get great overhangs, so most of these overhang improvement tips also translates to bridging.
- Get a high quality fan – the Noctua fan is a great upgrade that thousands of users love
- 3D print yourself a Petsfang Duct (Thingiverse) or another type of duct (Ender 3) which is proven to work very well
2. Decrease Layer Height
The next thing you can do is decreasing the layer height, which works because it reduces the angle at which your extruded layers are working at.
When you picture your extruded layers like a staircase, the larger the staircase, the more material is off the edge of the previous layer, which in other words is overhang.
On the other side of this scenario, a smaller staircase (layer height) means that each layer has a closer foundation and supporting surface to build upon for the next layer.
Although it will increase printing time, sometimes its necessary to get those awesome overhangs, and sweet print quality. The results are usually better than the sacrifice in time!
The video below by the 3D Printing Professor illustrates this really well.
The default layer height in Cura for a 0.4mm nozzle is a comfortable 0.2mm which is 50%. The general rule for layer height relative to nozzle diameter is anywhere from 25% to 75%.
This means you can use a range of a 0.01mm layer height up to 0.03mm.
- I would try using a layer height of 0.16mm or 0.12mm for your 3D printer
- Make sure you are implementing ‘Magic Numbers‘ for your layer height so you aren’t micro-stepping.
3. Change the Orientation of Your Model
The orientation of your model is another trick you can use to your advantage to reduce overhangs. What this means is, you can rotate and adjust your 3D print model to decrease the angles at which the model is printing.
This may not always work, but in some cases it can work perfectly.
You might not be able to decrease angle below 45°, but you can get pretty close.
For resin 3D printing, its advised that you orient your 3D prints to be 45° to the build plate for better adhesion.
- Rotate your models to reduce overhang
- Use software to automatically orient your 3D print models.
Makers Muse has a great video describing the details behind print orientation in terms of strength & resolution, giving you a better understanding of how important print orientation is.
He describes how there is always a trade-off when it comes to orientation, and in some cases you can get the best of both worlds. It takes a little bit of thought and knowledge of how layers make up parts to get things right.
4. Reduce Your Printing Speed
This tip is somewhat related to the cooling aspect of things, as well as better layer adhesion. When you reduce your printing speed, it means your extruded layers have more time to benefit from cooling, so it can create a good foundation.
When you combine a reduced printing speed, with improved cooling, a decrease layer height, and some great part orientation, you can significantly decrease the presence of overhangs in your 3D prints.
5. Reduce Your Printing Temperature
The optimal temperature for your 3D printer is one which extrudes nicely at the lowest possible temperature. You don’t want to use a nozzle temperature higher than you actually need, unless you have other goals in mind.
The reason behind this is that your filament will be more liquid and hotter than it needs to be, so cooling won’t be as effective with a more melted filament, thereby contributing to decreased overhangs.
A higher print temperature can help out with increasing part strength or reducing under-extrusion issues, but if you fine-tune your 3D printer, you can usually fix many issues without using temperature as a solution.
I would do some trial and error by using a temperature tower, calibrated to test several temperatures within the range of your filament.
For example, a 10 part temperature tower and a filament temperature range of 195 – 225°C can have a starting temperature of 195°C then increase in 3°C increments up to 225°C.
You can really dial in a perfect temperature using this method, then seeing the lowest temperature where your print quality looks great.
- Find your optimal printing temperature
- Make sure your not using a higher temperature than you need as it can lead to high flow of material
6. Decrease Layer Width
This method works somewhat because it decreases the weight of each extruded layer of material. The less weight your layer is, the less mass or force behind it hanging over the previous layer.
When you think about the physics of overhangs, it relates back to the decreased layer height and being able to better support its own weight at the overhang angle.
Another benefit with decreasing your layer width is having less material to cool down, resulting in a faster cooling of the extruded material.
Decreasing your layer width may unfortunately increase your overall printing time because you are going to be extruding less material.
7. Split Your Model Into Multiple Parts
This is a method that is a little more intrusive than the others, but it can work wonders with troublesome prints.
The technique here is to split your models into sections that reduce those 45°. Check out the video by Josef Prusa below for a simple tutorial within the Meshmixer software.
3D printer users also do this when they have a large project and a relatively small 3D printer which can’t fit the whole piece. Some prints are split into several parts to make one object, such as a Stormtrooper helmet which takes over 20 pieces.
8. Use Support Structures
Using support structures is kind of the easy way out for improving overhangs, because it is creating that supporting foundation rather than letting the overhang work its magic.
In many cases you will find it hard to completely avoid support material, no matter your orientation, layer height, level of cooling and so on.
Sometimes you’ll just have to go ahead and add in your support structures via your slicer. There are some slicers out there which allow you to closely customize your supports
The video below by CHEP shows you how to add custom supports using a special plugin, so feel free to check that out to reduce your supports.
9. Integrate a Chamfer Into Your Model
Integrating a chamfer into your model is a pretty good method to reduce overhangs because you are reducing the actual angles of your model. It’s described as a transitional edge between two faces of an object.
In other words, rather than have a sharp 90° turn between two sides of an object, you can add a curvature which cuts away at a right-angled edge or corner to create a symmetrical sloping edge.
It’s usually used in carpentry, but it definitely has great uses in 3D printing, especially when it comes to overhangs.
Since overhangs follow the 45° rule, a chamfer is perfect for improving overhangs when it can be used. In some cases a chamfer won’t be practical, but in others, they work out nicely.
Chamfers do significantly change the look of models, so keep this in mind.
10. Tune Up Your 3D Printer
The last thing to do which doesn’t specifically relate to overhangs, but to overall 3D printer quality and performance is to simply tune up your 3D printer.
Most people neglect their 3D printer over time, and don’t realize that regular maintenance is a good idea for your print quality. 3D printers are very durable, but they do consist of parts which need some extra care such as belts, rollers, the print nozzle and rods.
- Check over your parts & make sure you replace parts that are noticeable worn out
- Tighten up screws around your 3D printer as well as your belts
- Regularly apply some light machine or sewing oil to your rods to help them move smoother
- Clean out your extruder and fans since they can easily build up dust and residue
- Ensure your build surface is clean and durable
- Run a cold pull every so often – heat up the nozzle to 200°C, insert filament, reduce heat to 100°C then give filament a firm pull.
There are many methods to improve your overhang which work pretty well. Hopefully this article has steered you in the right direction to finally get some overhangs that you can be proud of.