What Is the Z Hop / Lift Z Feature in Cura / PrusaSlicer?

If you regularly use Cura or PrusaSlicer, you most likely have stumbled upon the “Z Hop When Retracted” checkbox (Cura) or the “Lift Z” input box (PrusaSlicer) for activating Z-Hop, which is quite a controversial feature due to how it can impact a print.

In this article, we will explain the purpose of the Z-Hop / Lift Z feature you can find in Cura and PrusaSlicer, discuss the advantages and disadvantages it can bring to your prints, take you through the process of finding the optimal Z-Hop Height / Lift Z value, and take a quick look at how you can enable and configure this feature in Cura and PrusaSlicer.

What Is the Z Hop / Lift Z Feature in Cura / PrusaSlicer?

Z-Hop, also known as Vertical Lift, Z-Hop When Retracted (Cura), and Lift Z (PrusaSlicer), is a feature that causes the 3D printer to move the printhead up (or the build plate down) by a specified margin and at a specified speed (only customizable in Cura), after each retraction, right before a travel move takes place.

cura z hop when retracted checkbox


Whenever the printhead makes an upward movement as a result of the Z-Hop feature being triggered, it stays at the Z-axis position it has moved to until it completes the travel move and only moves down to its original Z-axis position once it reaches the point where extrusion needs to start again.

z hop explanation


As a result of this movement, space is created between the nozzle and the part that’s being printed, making it practically impossible for the nozzle to unwarrantedly come into contact with the part during a travel move, provided that the Z-Hop feature is correctly configured.

Advantages and Disadvantages of Using Z Hop / Lift Z

As Z-Hop is a feature with both advantages and disadvantages, finding out whether enabling it would be worthwhile in your case is the first step you should take to ensure that it doesn’t have any adverse effects on your prints.

When we take a look at the advantages of the Z-Hop feature, the first thing that comes to mind is that it prevents the nozzle from possibly touching the print during travel moves, which protects the surface of your prints from the scarring that occurs if the nozzle makes contact with the print’s surface at any point; an issue that can considerably reduce the visual quality of your print.

scarring on top surface of print
Source: theMouse @ Stack Exchange (CC BY-SA 4.0)

Additionally, in cases where blobs are present on the surface of your print, both the possibility of the nozzle coming into contact with your print (due to the added height the blobs bring) and the damage such an event can cause will drastically increase, as the nozzle coming into contact with a larger chunk of the print can potentially result in the nozzle knocking the print off completely (especially if you’re printing a tall and thin model that’ll easily fall down, such as a tower), which is another thing Z-Hop will protect your print from.

nozzle knocking print off
Source: Micah Henning @ Stack Exchange (CC BY-SA 4.0)

Finally, one last advantage of the Z-Hop feature is that it makes it more likely for any material that oozes during a travel move to end up in the infill instead of on the surface due to the nozzle fully avoiding the printed areas, which can considerably reduce the appearance of blobs on the surface of your prints.

blobs on 3d printed model example
Source: Bort @ Stack Exchange (CC BY-SA 4.0)

On the other hand, the primary disadvantage of using the Z-Hop feature is that it makes the printing process take longer periods of time, and even though the very slight up & down Z-axis movements shouldn’t make a considerable difference in most cases, especially if you print small to medium-sized models or models that don’t require a lot of retraction, in general, it’s still something to keep in mind when optimizing print times.

Additionally, the added movement to the Z-axis can cause the Z-axis components, such as the lead screw, to wear down faster than usual, and while we don’t think this is grounds to avoid this feature altogether, especially considering that the added wear will only present itself over a prolonged amount of time, it’s still a minor disadvantage that’s worth mentioning.

While not direct disadvantages of the Z-Hop feature, printing with Z-Hop enabled is also known to exacerbate retraction and Z-axis-related issues, as the Z-axis movements it adds will create more room for things to go wrong, leading users to believe that Z-Hop is the culprit when it actually isn’t.

For instance, a common complaint regarding the Z-Hop feature is that it increases stringing, and while this will definitely be true in cases where the retraction settings aren’t configured correctly in the slicer, it’s not actually a fault of the Z-Hop feature itself, but rather Z-Hop being active making a bad situation worse.

z hop stringing example
Source: iPhoenix @ Stack Exchange (CC BY-SA 4.0)

Regardless, the correct course of action, in this case, would be to fix retraction settings, in which case stringing shouldn’t occur, regardless of whether you’re using Z-Hop.

Similarly, another issue that many users face once they enable the Z-Hop feature is the appearance of Z-axis artifacts when, in fact, activating Z-Hop wouldn’t create such an issue on its own but amplify the adverse effects already caused by issues related to the Z-axis, such as a problem regarding the alignment of the Z-axis lead screw, or Z-axis backlash due to poor Z-axis mechanics.

z axis artifacting example
Source: kosteklvp @ Stack Exchange (CC BY-SA 4.0)

Once again, the correct thing to do, in this case, would be to fix the source of the problem and correctly align the Z-axis lead screw or install an anti-backlash nut; rather than view the Z-Hop feature as the source of the issue.

With these advantages and disadvantages in consideration, we can say that it would be suitable to enable the Z-Hop feature if you’re having issues regarding the nozzle touching the surface of your prints or if you’re having problems with blobs that you haven’t been able to solve otherwise, such as correcting your retraction settings and printing temperature, and to keep it disabled otherwise as it will only bring negatives without any benefit in such a case.

Finding the Optimal Z Hop Height (and Speed) / Lift Z Values

The next thing you will need to do when enabling the Z-Hop feature is to configure the Z-Hop height (and speed on Cura) value, which determines how much the 3D printer will raise the printhead when it performs a Z-Hop (and how quickly it moves up and down).

When configuring the Z-Hop height value, the primary goal is to find the spot where the clearance is just enough to prevent the nozzle from making contact with the print, as needlessly raising this value will cause your 3D printer to make extra unnecessary movements and further increase print times.

In Cura, the default value for Z-Hop height is 0.2 mm, which is one that we can consider a pretty standard starting point that should usually work without issues in many cases, and as a result, one that we recommend keeping until you come across problems that may require you to increase it.

cura z hop height


If the starting value isn’t working for you, with the clearance still not being enough for the nozzle to go through without collision, our recommendation would be to raise it 0.1 mm at a time based on your observations of the test print and to keep testing until you find the value that produces the desired results.

That being said, as the conditions can vary across prints based on the model you’re printing (such as models with features prone to curl upward requiring more clearance), you might have to raise the Z-Hop height value even further than what you used without issues earlier, which is also something to keep in mind.

On the other hand, when it comes to Z-Hop speed, the goal should be to find the highest value that doesn’t cause issues (such as the Z-axis stepper motor skipping steps and mispositioning the nozzle after a Z-Hop, which could lead to print failure), as performing the Z-Hop as quickly as possible will move the nozzle off the surface sooner, and reduce the chance of a blob ending up on the surface.

cura z hop speed


That being said, as the Z-Hop speed that a printer can handle depends entirely on its hardware, such as whether a dual Z-axis system is present or not, our recommendation would be only to optimize it accordingly if you’re aware of your 3D printer’s limits, or else to leave it at 5 mm/s, as a too-high Z-Hop speed value will create more issues (Z-axis skipping steps) than a low Z-Hop speed value.

Enabling & Configuring the Z Hop Feature in Cura

As the Z-Hop feature is called “Z-Hop When Retracted” in Cura, this is the setting you will need to look for as a Cura user.

To find this feature in the most convenient way possible in Cura, you need to type “Z-Hop” into the search input of the Print Settings section, which will make the Z-Hop When Retracted checkbox visible on your screen.

cura z hop when retracted checkbox


Once you check this checkbox, the Z-Hop feature will be active, and additional settings that allow you to configure the Z-hop feature will also become visible; Z-Hop Speed, Z-Hop Only Over Printed Parts, and Z-Hop Height.

cura z hop when retracted enabled


While Z-Hop Speed and Z-Hop Height are pretty self-explanatory, as we have already covered in the previous section, the Z-Hop Only Over Printed feature is particularly interesting since it practically flips the triggering condition of a Z-Hop around.

With Z-Hop Only Over Printed enabled, your 3D printer will prioritize avoiding other objects horizontally, as opposed to performing a Z-Hop to avoid them vertically, and only perform a Z-Hop when there’s absolutely no way to go around a printed part, whereas standard Z-Hop behavior would be to just avoid any printed part vertically instead, without considering a horizontal avoiding path.

Additionally, while not directly related to the Z-Hop feature itself, another thing worth mentioning is the relationship between Z-Hop and Combing, as the Z-Hop feature being active also changes the behavior of Combing, which is something to keep in mind.

To explain things in a simple way, we can say that Combing and Z-Hop will never occur at the same time, as Z-Hop will replace Combing whenever the conditions of the nozzle crossing a wall, and the Z-Hop feature being enabled are satisfied.

Similarly, as Combing keeps the nozzle within printed parts and causes it to avoid crossing walls as much as possible, there will be fewer chances for a Z-Hop to take place, which can even lead users to believe that the Z-Hop feature isn’t working in some cases.

z hop combing retraction flowchart for curaengine
Source: Ghostkeeper @ GitHub

Finally, if you would like to deactivate the Z-Hop feature, you will need to uncheck the Z-Hop When Retracted checkbox, which will also cause the related settings to be removed from the menu again.

Enabling & Configuring the Lift Z Feature in PrusaSlicer

In PrusaSlicer, you will find the Z-Hop feature listed as Lift Z, which automatically activates once you enter a positive value inside the input box.

To get there as quickly as possible, all you will need to do is to switch to the Printer Settings tab on the top of the PrusaSlicer window and choose the Extruder 1 menu from the left pane, which will make the Lift Z input visible under the Retraction section.

prusaslicer lift z in menus


Once you enter the height value of your choice in the Lift Z input, the feature will become active, and the printhead will go up by this amount before each travel move takes place after a retraction.

prusaslicer lift z configuration


On the other hand, to deactivate the Lift Z feature, you can enter 0 into the input box instead.

Conclusion

While Z-Hop definitely isn’t a feature that will be beneficial in every single scenario, activating it will definitely come in handy in cases where the nozzle unwarrantedly comes into contact with the print during travel moves and causes damage as a result, whether it’s scarring the surface, leaving blobs on it, or knocking the print off completely.

That being said, on top of correctly deciding when to activate Z-Hop, ensuring that you have correctly configured the Z-Hop height (and speed) is also essential to get the maximum benefit possible out of this feature, as a misconfiguration can quickly turn it into something that has a negative effect on your prints rather than improving its quality.