A typical 3D printing artifact is the stair-stepping effect, where the layers making up a 3D printed object become distinctly visible. The result is the appearance of a staircase on the side of your final print, where there should be a smooth surface. These sharp edges can reduce your print’s aesthetic quality and significantly lower your work’s quality.
3D printed objects show the stair-stepping effect mainly because layering is integral to 3D printing. The effect is more visible with thicker layers and in prints with curved or angled surfaces. Also, using a technique like SLA 3d printing lowers visibility compared to technologies like FDM 3d printing.
Read on for an explanation of how layering results in the stair-stepping effect. I’ll also discuss how to minimize the occurrence of stair-steps during printing and reduce visibility after printing is complete.
How 3D Printing Automatically Results in the Stair-Stepping Effect
Ideally, a 3D printed object should have smooth sides that seem continuous. Practically, this is impossible. Even so, 3D printing specialists always work to get as close to the ideal situation as possible.
Layering is integral to 3D printing techniques, from Fused Deposition Modeling (FDM) to sintering techniques like Selective Laser Sintering (SLS) and resin-curing techniques like Stereolithography (SLA).
Regardless of technique, for an object to be 3D printed, a computer program first slices the related design into layers, which is where your stair steps start.
3D Printers Work in Layers
When you print an object, the 3D printer receives layer-specific instructions and prints the object layer by layer.
These layers are then “stacked,” and the final object will be a stack of layers.
The trick to reducing layer lines is to make the merging of the layers appear as seamless as possible.
If you succeed, the result is a smooth, aesthetically-pleasing object. These imperceptible transitions are critical in 3D printing applications where aesthetic appeal directly correlates with quality.
If you fail, you get the stair-stepping effect. The more visible the steps are, the less attractive your print will be. In some cases, these rigid layer lines will also reduce the quality of your object.
The extent of the stair-stepping effect depends on various factors, which you can tweak, as I’ll discuss below.
How To Minimize the Degree of Stair-Stepping in 3D Printing
The following factors affect the extent of stair-stepping when printing 3D objects:
- Layer thickness
- Object geometry
- Technology used
I’ll discuss each factor in detail below.
As long as you are 3D printing an object, you must work in layers. You can’t go around that. However, you can determine the height of the layers, which is their thickness.
Printing with thick layers is generally favorable. It takes less time since the nozzle extrudes more filament while working on each layer. The time savings are usually significant.
However, thick layers come with a downside. The wider the layer, the more visible it is, and the more visible the stair-stepping effect.
If your priority is to reduce the staircase effect, you’ll want to work with a small layer height. The layers will be less visible, and the 3D print will be smooth. Sometimes, it can be so seamless that you must use a magnifying glass to see the layers.
The obvious disadvantage is that you’ll take significantly longer to finish the print.
When aesthetic quality is crucial, longer turn-around times may be an acceptable tradeoff.
As a bonus, with a smaller layer height, you can effectively 3D print objects with intricate designs.
The stair-stepping effect’s degree also depends on the nature of your 3D model.
If the object you want to print has angled or curved parts, the staircase effect will be amplified. If the thing has straight edges, it will most probably appear smooth.
The relationship between the angle of the print and the degree of the staircase effect is continuous.
Let’s use the vertical axis as our reference point. The lower the angle from the vertical axis, the less the stair-stepping effect. The higher the angle from the vertical axis, the higher the extent of stair-stepping.
As the angle increases, it becomes easier to single out individual layers.
To reduce the staircase effect, you can tweak this factor right at the design stage by reducing the angles and curvature of the object.
However, most times, changing the geometry of an object to reduce the staircase effect will result in a different model. For example, if you want to print a sphere, changing the geometry may result in flat surfaces with sharp edges.
In such cases, the only way to control side-stepping is to tweak the other factors like layer thickness.
While the underlying principle of 3D printing is the same, various means exist to achieve the same result.
You can use different technologies. Your choice of technology depends on several factors, including the available equipment and the qualities you want your final object to possess.
Though all 3D printing technologies rely on layering, different technologies result in varying degrees of the stair-stepping effect.
Fused deposition modeling is the most notorious technology for the stair-stepping effect. On the other end of the spectrum, Stereolithography seems to result in less visibility of the staircase effect.
Reducing the Appearance of Stair-Stepping After 3D Printing
Effectively combating stair-stepping during printing can be costly. For example, reducing the layer height can result in considerably longer turn-around times for prints.
An alternative is to alter the appearance of 3D prints after they are ready, which can be more economical. However, it’s not suitable for all 3D printed objects as it can reduce structural integrity, which can be a significant problem with delicate parts.
However, there are still ways to improve a bumpy print. You can use the following methods to change the surface quality of an object after it has been 3D printed:
- Surface coating
Surface coating involves covering the object with a chemical. You can apply it to the model using a brush or spray.
Surface coating fills the gaps on the object’s surface, resulting in a smoother finish. After applying the chemical, you allow it to cure. This coating will harden to give your model a seamless outer surface.
For an even smoother surface, you can apply more than one coat. Wait for the first coat to cure, then spread a second coat.
One downside of this method, which could be significant depending on your use case, is that the dimensions of your 3D printed object change. With a second coat, the difference is even more prominent.
That said, surface coating effectively minimizes the staircase effect’s appearance and improves the smoothness of a 3D print.
Polishing uses mechanical means to smooth out irregularities on a 3D printed object. You can use it to reduce the appearance of the staircase effect.
You can polish your 3D prints with the following methods:
3D printed objects are essentially a stack of layers. The easier it is to notice the layers, the more visible the stair-stepping effect is.
Working with a smaller layer height can reduce the staircase effect during printing. However, this decrease in layer height can result in a significant increase in the time it takes to finish the print.
After printing, you can reduce the staircase effect by polishing your print or coating it with a chemical.