Should You Enable Coasting While Printing with PETG? (Solved!)

The most intriguing section in Cura’s print settings is, without a doubt, the Experimental settings, where it’s possible to find features that can improve your prints with the click of a button when used correctly or even transform them into something else; such as creating a mold.

On the other hand, as the name states, these features are indeed experimental, meaning that they won’t always necessarily be beneficial to the printing process and can even affect your prints unfavorably when misconfigured or enabled in the wrong scenarios.

In today’s article, our topic will be the coasting feature in Cura and how well it works with PETG filament, where we will try to deduce if coasting is a beneficial feature to enable us to take our prints to the next level while printing with PETG.

So, should you enable coasting while printing with PETG filament?

As PETG is a type of filament that is highly prone to oozing, enabling the coasting feature in Cura for printing with PETG can be pretty helpful to reduce or eliminate oozing without any drawbacks as long as you configure the coasting parameters correctly.

In the upcoming sections, we will discuss whether enabling coasting while printing with PETG is a good idea or not in more detail, find out how exactly coasting affects the printing process, and take a quick look at the steps for activating and configuring coasting for PETG in Cura.

Should You Enable Coasting While Printing with PETG?

Considering that coasting is a feature designed to reduce stringing and that PETG is notorious for stringing problems, the combination of PETG and coasting indeed looks like a fantastic idea.

Due to oozing being a common issue with PETG filament, enabling coasting in Cura for your PETG preset is definitely a good idea if you’re also suffering from the frequent problem of oozing ruining your 3D printed models by creating strings and blobs on its surface.

On the other hand, as coasting comes with a set of parameters that require precise configuration to operate correctly, getting the most out of this feature will most likely require some experimentation on your part, especially considering that a misconfigured set of coasting parameters can do more harm than good.

The only time we don’t recommend enabling coasting for printing with PETG is if you’re observing under-extrusion, which, while highly unlikely for PETG in standard conditions, is still worth mentioning as it will cause the under-extrusion to become even more severe.

How Does Coasting Affect Printing with PETG Filament?

Understanding how enabling the coasting feature of Cura affects the printing process while printing with PETG filament is the most optimal way to decide whether you need to activate coasting or not.

Once you enable coasting, Cura will instruct your 3D printer to replace the last bits of the extrusion path with a travel move instead, stopping the extruder from extruding any more PETG as it completes its movement.

In an optimal scenario, as a result of this change, the extruder ends up using the leftover PETG to print the last bits of the extrusion path, which otherwise could have oozed out of the nozzle once the extruder completes its path and moves towards the next one.

On the other hand, it’s worth noting that in the case of a misconfiguration, coasting can cause the last parts of each extrusion path to suffer from under-extrusion, as the feature essentially cuts the filament supply off to prevent oozing. 

How to Activate Coasting in Cura for Printing with PETG?

Activating the coasting feature in Cura is far from a challenging task, as you can find it alongside all the other print settings Cura offers without the need for installing or configuring anything extra.

Below is a step-by-step guide you can follow to activate coasting in Cura for printing with PETG:

  1. Navigate to the Prepare tab of Cura, which you can find at the top of the window.
  2. Click the middle pane, which contains the current material and nozzle size information.
  3. Click the Material dropdown, hover over the Generic tab, and choose PETG from the list, which will load Cura’s default settings for PETG.
  4. Click the rightmost pane, which contains information about the current print profile and print settings.
  5. Click the “three lines” icon next to the search input, and choose the All option from the dropdown menu to make all settings visible.
  6. Type “coasting” into the search input.
  7. Check the Enable Coasting checkbox to enable the coasting feature.

When you activate the coasting feature in Cura, the three coasting-related parameters, coasting volume, minimum volume before coasting, and coasting speed, will be visible and ready for configuration.

How to Configure Coasting in Cura for Printing with PETG?

As the coasting feature brings a few parameters to the table that need configuring when you enable it, ensuring that you configure these parameters is paramount for coasting to work optimally.

Below is a list of Cura’s coasting-related parameters, where we describe their purposes and our recommendations for configuring them as optimally as possible:

  • Coasting Volume – Determines the volume of the plastic that will be coasted, meaning that the 3D printer will stop extruding filament when the amount of plastic required to complete the path is equal to this figure. Cura suggests calculating this value by taking the cube (for instance, for a 0.4 mm nozzle, the value would be 0.4^3 = 0.064) of your nozzle’s diameter, which we have found to be effective.
  • Minimum Volume Before Coasting – Determines the minimum volume of plastic a path should have for coasting to activate. As oozing is more likely to occur during the printing of larger extrusion paths (which increases extruder pressure), experimentation is key to finding the optimal value here. A significant point of consideration is that this value has to be larger than the coasting volume value.
  • Coasting Speed – Determines the speed of the extruder during the coasting process relative to the speed of standard extrusion. Going for a slightly lower value than 100% is recommended due to the drop of pressure in the extruder during coasting.

Once you’re done configuring all of the coasting parameters, we highly recommend saving your changes into a custom profile to combine them with Cura’s default PETG settings (or your custom PETG profile if you have one).

Wrapping Up

As PETG is infamous for causing stringing issues, it definitely makes sense on paper to enable Cura’s coasting function to reduce or even entirely prevent stringing, especially considering how effortless the process of activating and configuring coasting is.

To quickly recap, due to PETG’s ooze-prone nature that frequently causes the bothersome issues of stringing and blobbing, enabling the coasting feature in Cura is something we definitely recommend to minimize oozing as much as possible if you’re having problems with it.

While coasting is highly unlikely to cause any trouble with a correctly configured set of parameters, enabling the feature if you don’t experience any oozing is not the best idea due to the possibility of it causing under-extrusion towards the ends of the lines.

Happy printing!