How To Improve Rough Overhangs on a 3D Print

3D printing is rapidly becoming one of the most popular methods of model creation. Overhangs are an important component of printing and can have a major effect on the end-product of the model print.

Here’s how you can improve rough overhangs on a 3D print:

1. Decrease the printing temperature.
2. Reduce the print speed.
3. Print in segments. 
4. Alter the orientation of the model.
5. Use support structures. 
6. Decrease the layer height.
7. Increase the intensity of fan-cooling.
8. Avoid printing overhangs beyond 45 degrees.

Improving your overhangs will allow you to render a more structurally sound and visually appealing model. Keep reading for more information on how to improve overhangs and some technical details on how to make the proper adjustments to your 3D printer. 

What Is an Overhang in 3D Printing?

An overhang in 3D printing is the product of the traditional layer-by-layer printing method. An overhang occurs when the 3D printer prints beyond the previous layer, essentially printing away from the support of the rest of the model and out into empty space. 

Without the structural foundation of the model underneath, overhangs tend to encounter more stability and support problems, making them a challenge for newer printing enthusiasts. They’re an essential element of 3D printing. However, a rough overhang can rapidly reduce the quality of the end product. 

What Makes an Overhang “Rough”?

An overhang can be printed “rough” if the settings aren’t quite right, typically occurring when the printer isn’t sufficiently cooling the plastic during the print. However, there are a few other factors that can cause this problem as well. 

A poorly designed model can cause rough overhangs during the print. But if you cannot find anything wrong in the printer settings, double-check the model design to make sure it’s structured for smooth printing.  

Fortunately, there are ways you can improve rough overhangs on a 3D print.

1. Decrease the Printing Temperature

The most common cause for rough overhangs in 3D printing is a temperature issue. When an overhang is printed out beyond the support of the previous layer, it can either droop or curl if the temperature isn’t set correctly. 

The temperature of the plastic when it’s extruded from the nozzle dictates how long the plastic takes to cool and solidify. If the plastic is too hot, therefore taking too long to cool in place, the overhang may naturally droop or curl, which results in a rough surface in the final product. 

Drooping Overhangs

Drooping occurs in 3D printing when the force of gravity pulls the plastic overhang down before it has time to cool in position. This typically happens when the print temperature is set too high. When the overhang is drooping, you may also notice beads of molten plastic dripping down from plastic extrusion. 

Curling Overhangs

A curling overhang can also occur when the plastic is extruded too hot. If the overhang is too hot, the plastic may begin to warp upwards or “curl.” This can cause serious damage to the rest of the print, especially if the overhang curls up beyond the nozzle height. 

How To Reduce the Print Temperature on a 3D Printer

Users should be able to toggle the temperature settings of their printer using the “Edit Process Settings” menu.

Reduce the printing heat by a few degrees and try to print again. If you’re still noticing drooping or curling overhangs, turn the temperature down a few more degrees.

You should only need to adjust the temperature setting by 5-10 degrees. Begin by setting the temperature at 200 degrees celsius, adjusting as needed in small increments. 

2. Reduce the Print Speed

Reducing your print’s speed can help establish a sturdier base, which allows for a smoother overhang. However, the danger of reducing your print speed is that the nozzle tends to overheat, increasing the risk of the overhangs drooping or curling and an increased general risk of deformation during the print. 

Be sure to adjust the printer cooling in relation to the decreasing print speed to avoid overheating. You can also mitigate this risk by increasing the fan cooling intensity, enabling the supportive structures and layers to be adequately stable when the overhang layer is printed. 

How To Adjust Print Speed in Settings

To adjust the speed at which your extrusion nozzle prints your model, you’ll need to make some changes in the secondary settings.

Here are some of the setting adjustments that’ll help you slow down your print speed, which can help you achieve smoother overhangs. 

• Outer shell/outer wall print speed: This dictates the speed at which the model’s perimeter is printed. Surface smoothness and structural integrity, which allows for better overhangs, can be improved by decreasing the outer wall print speed. 
• Inner shell/inner wall print speed: This dictates the speed at which the model’s interior perimeters are printed. In general, the inner shell print speed is roughly equivalent to the overall printing speed. Making reductions in this setting can improve the surface smoothness but also risk damaging the structural integrity by overheating the plastic filament. 
• Infill print speed: This dictates the speed at which the infill is printed. The infill is the element of the model which must be printed in between the inner and outer shells/perimeters. Similar to the shell print speed settings, you can slightly reduce the infill print speed to improve print smoothness, but you must take into account the strength. 
• Top/bottom speed: This dictates the speed at which the bottom and top layers: of the model are printed. You can reduce the speed to improve the surface smoothness of the final product. 

3. Print in Segments

Another method of improving the smoothness of your overhangs in 3D printing is to print the model in segments. Rough overhangs occur when the model requires filament to be printed at a steep angle beyond the edge of the previous layer. 

Printing the model in multiple segments allows for each element of the model to be printed without dramatically steep overhangs. This is most beneficial when the model shape requires steep overhangs.

Simplifying the complexity of each segment the printer has to manufacture will allow each of those segments to be printed at a higher quality. 

Slicing the model by running the file through a slicer before sending the segments to the printer can be beneficial to improving your overhangs. Slicing when the overheads are flat allows for two mirror models to be printed. These pieces can then be adhered together, creating an overall smoother finished product. 

Some print jobs, especially if the model is large or requires a number of steep extrusions, will naturally be broken down into multiple smaller print jobs. 

4. Alter the Orientation of the Model

If the model being printed is asymmetrical, requiring a steep overhang on one side of the model and not the other, then repositioning the model in relation to the print bed and cooling fan can be helpful. Fans are typically located on the heatsink of the 3D printer’s hot end. 

The fans’ intended function is to cool the parts within the printer. However, the steady flow of cold air can also serve to cool and solidify the plastic filament. Keeping this in mind, reorienting the model so that the fan is directly cooling the overhang while the filament is being extruded can help ensure the stability of the structure. 

5. Use Support Structures 

A support structure is an additional element of the model that is printed to support an overhang. Some 3D printers try to avoid using support structures to maintain the visual aesthetic’s integrity. 

However, suppose the original model design doesn’t provide structural support for a bridge or overhang. In that case, an additional support structure may be required to keep the plastic from being pulled down by gravity. Not all overhangs require structural support, though.

Overhangs printed at an angle of 45 degrees or less are often strong enough to hold up without additional support. 

For example, if the model’s overhangs extend horizontally out from the main body of the model, like the arms of a “T,” then the bridges or overhangs will likely require support structures. If the overhangs extend away from the body of the model at a positive diagonal, like a “Y,” then you may not need support structures. 

6. Decrease the Layer Height

Decreasing the layer height essentially reduces the angle at which the extrusion is printed. By reducing the thickness of each layer and making the highest “surface point” of each layer closer together, you can print the overhang without as steep of an angle between each layer.

The downside of decreasing layer height is that the overall print time will be longer. However, a slower process is rewarded with a smoother finish and better quality overhangs, making the finished product look more professional. 

7. Increase the Intensity of Fan-Cooling

The fans in a 3D printer are installed to cool the printer’s internal parts, preventing overheating.

The cold air expelled from the parts fan can serve a double function. It cools the fan’s interior and the plastic filaments being printed. 

Increasing the intensity of the parts fan in the system settings can help the plastic filament cool and solidify faster. A faster cooling time allows the molten plastic overhangs less time to curl or droop.

Here are a few ways to toggle the intensity of your 3D printer’s fan cooling in the system settings. 

• Keep fan always on: Enabling this function in the system settings will prevent the fan from turning off. This is useful when printing with PLA thermoplastic filament but not with ABS. 
• Auto cooling: Cooling logic can be toggled in the settings, which allows the printer to apply more or less fan cooling intensity based on the model and G-code. 
• Fan speed: The minimum and maximum fan speeds can be adjusted in the system settings. Increasing fan speed can allow more cold air to be blown out onto the cooling plastic during the print. 
• Bridges fan speed: By enabling this setting, users can set the printer to increase fan speed and intensity when printing a bridge over empty space. This setting allows for the additional cooling intensity to be used when needed without running the risk of over-cooling the print bed during the rest of the job. 

Adding Fans Can Help Improve Rough Overhangs

Most systems permit users to add on additional fans using the spare connector. Users can dictate the additional fan to cool and stop as needed using the print model’s G-code. The extra cooling power of an additional fan will help the plastic cool as it’s printed, improving the structural quality of the overhang layer. 

When positioning an additional fan, it’s important not to over-cool the printing bed or the hot end’s heater block. Over-cooling these parts will cause the printer to consume more energy unnecessarily. Situate the fan so that the air cools the plastic filament as it’s extruded from the heated nozzle. 

8. Avoid Printing Overhangs Beyond 45°

As a general rule, overhangs with an angle of 45 degrees or less are more structurally sound. Overhangs and bridges printed at a horizontal or negative diagonal will likely droop if not assisted by structure supports. 

Planning your model design with this in mind will help to yield a smoother, more professional-looking final product. Cooling methods and some setting adjustments can assist with rough overhangs, but the best way to ensure a smooth overhang is to ensure the angle is at 45 degrees or less during the design process. 

Final Thoughts 

Printing a smooth overhang can make all the difference in the final product. Overhangs in 3D printing occur when the perimeter of a layer has to be printed beyond the perimeter of the previous layer.

If the plastic is printed too far out over the edge of the previous layer, gravity pulls it down, ruining the structure of the print. 

You can resolve this problem by slowing the print speed, increasing the cooling intensity, and avoiding printing overhangs at an angle beyond 45 degrees away from the main body without support structures.