What Is Horizontal Expansion in Cura? (How to Use It?)

Despite being a technology that advances every day, 3D printing isn’t entirely perfect just yet. As a result, there are plenty of cases where the printed model isn’t exactly identical to the digital model you see in the slicer software, with issues such as warping and shrinkage troubling enthusiasts.

Fortunately, slicer software is evolving every day and bringing new features to compensate for such situations, allowing you to avoid or minimize the issues through the fine-tuning of these features.

Today, our topic will be one such feature that comes in handy to compensate for the dimensional differences between the digital and the printed model, called horizontal expansion.

So, what is the horizontal expansion feature in Cura?

Horizontal expansion is a feature in Cura that allows you to add an offset to the X and Y dimensions of the model you’re printing, allowing you to practically compensate for the differences between the digital and the printed model.

While it sounds straightforward at first, there are some nuances that you need to be aware of before using horizontal expansion to get the results you expect from it.

In the next section, we will take a deeper dive into how horizontal expansion works and look at examples where the feature comes in extremely handy.

What Is Horizontal Expansion in Cura?

When used correctly, horizontal expansion is perhaps one of the most practical features in Cura to fine-tune your prints quickly and achieve the desired results.

In a nutshell, the value you input for the horizontal expansion parameter in Cura expands the object by that value in both X and Y axes, essentially changing the object’s dimensions.

For instance, imagine that we printed a standard cube with a digital model that shows dimensions of 10x10x10 mm, but the actual dimensions came out to be 9.8×9.8×10 mm.

In this case, we can print the cube again with a horizontal expansion value of 0.2mm to compensate for the difference between the printed object and the digital model, which will allow us to print a 10x10x10 cube.

While this is very straightforward, the confusing part about horizontal expansion comes into play when the model has holes, such as a hollow square that’s completely empty on the inside.

Let’s imagine a situation where we are printing a hollow square with dimensions 10x10x2 mm, where the dimensions of the empty space are 8×8 mm.

The physical model comes out with a space dimension of 7.8×7.8 instead, making the hole too small for our purposes, meaning that we would need to apply some horizontal expansion.

While the intuitive thing to do would be using a value of 0.2 mm horizontal expansion to make the model, and as a result, the hole larger, this isn’t exactly the case.

In this scenario, applying a positive horizontal expansion value will actually make the hole smaller due to the object expanding both inwards and outwards, resulting in an object with the dimensions of 10.2×10.2×2 mm, with the dimensions of the whole becoming 7.6×7.6 mm.

To make the hole bigger, we should use a negative horizontal expansion value of -0.2 mm, which will bring the dimensions of the hole to 8×8 mm, and the dimensions of the whole object to 9.8×9.8×2 mm.

Alongside the main parameter, the horizontal expansion feature offers two extra parameters that allow you to use the feature situationally:

  • Initial Layer Horizontal Expansion – This parameter allows you to use the horizontal expansion only for the initial layer of the print, which can come in useful to prevent issues such as elephant’s foot where the initial layer isn’t strong enough to support the model.
  • Hole Horizontal Expansion – This parameter allows you to choose a horizontal expansion value that the slicer will only apply to the holes in the print, where positive values mean larger and negative values mean smaller. An important thing to consider while using this parameter is to remember that your model won’t be expanding as a whole, meaning that holes getting too large can deform other parts of the object.

While there is some complexity involved with getting horizontal expansion right when there are holes included, there is no denying that it’s a practical tool once you get used to it.

How Do You Use Cura Horizontal Expansion?

Using the horizontal expansion feature in Cura is a simple task, which we have outlined the steps for below:

  1. Click the Prepare tab on the top of the Cura window.
  2. Click the rightmost pane to bring the Print Settings dialog up.
  3. Click the Custom button to switch to custom settings if you haven’t already before.
  4. Click the icon next to the search input, and choose All to make all settings visible, including horizontal expansion.
  5. Type “horizontal expansion” into the search input.
  6. Type the desired value into the Horizontal Expansion input (in millimeters).

If you wish to use the Initial Layer Horizontal Expansion and Hole Horizontal Expansion parameters, you can also find the inputs for them right below the Horizontal Expansion input.

Horizontal Expansion Not Working in Cura – What to Do?

While horizontal expansion not working in Cura isn’t that common of an issue, there is a scenario where using the feature can cause your object to disappear, prompting the slicer to show a print time of 0 minutes.

In the case of your slicer showing 0 minutes of print time after using the horizontal expansion parameter, the most likely culprit is that you have used a negative value that exceeds the thickness of your model.

For instance, if your model is a 10x10x10 mm cube, and you use a horizontal expansion value of -10 mm, the feature will completely offset the model’s dimensions, leaving 0x0 behind.

Does the Horizontal Expansion Setting Exist in PrusaSlicer?

While the horizontal expansion parameter is usually associated with Cura, a common question is whether it’s possible to use it in PrusaSlicer or not.

The good news is that it’s indeed possible to use the horizontal expansion feature in PrusaSlicer, which is named XY Size Compensation in this case.

You can find the XY Size Compensation setting by clicking the Print Settings tab and choosing the Advanced menu from the left pane, where you will see it under the Slicing section.

PrusaSlicer also features an extra parameter called Elephant Foot Compensation, which works similarly to Cura’s Initial Layer Horizontal Expansion. To find this parameter, follow the same steps for finding the XY Size Compensation setting, as they are both located in the same section.

Wrapping Up

Horizontal expansion is a feature that should be in every Cura-using 3D printing enthusiast’s toolkit as it can make life pretty easy in situations where fine-tuning the dimensions of the model in a quick way solves the issue you’re facing.

To quickly recap, the horizontal expansion feature expands the object in both the X and the Y axes by the amount you have specified, essentially enlarging it and increasing the amount of plastic that goes into it.

As the dimensions of the digital model and the 3D printed object aren’t always consistent, the horizontal expansion feature provides a quick way to compensate for the inconsistencies and print an object with the desired dimensions.

Happy printing!