Why Is My Ender 3 (Pro/V2) Not Reading STL Files? (Solved)

There is no denying that starting your 3D printing journey for the first time with no prior technical expertise definitely comes with a slight learning curve that requires you to become familiar with some of the standard procedures that allow you to conduct the 3D printing process.

Fortunately, 3D printing as a whole, whether it is following the procedure for a standard print or performing troubleshooting, comes with some well-defined guidelines that make the whole journey quite accessible, and correctly following these guidelines almost always leads to a successful print.

In this article, we will be talking about the incompatibility between the Ender 3 (or any 3D printer for that matter) and STL files, which are the 3D models that we use for the purposes of 3D printing, and explain why a 3D printer, such as the Ender 3, does not read the STL files despite them containing the data for the 3D model.

So, what is the reason behind your Ender 3 not reading STL files?

While files with the STL file format contain the necessary information for a 3D model in their contents, they don’t include the required print-specific data, such as the print speed or the print temperature, and as a result, it’s natural for your Ender 3 not to be able to use this file to print.

Moving forward, we will provide a more detailed explanation of why your Ender 3 is not reading STL files, find out how to convert the STL files to a format called G-Code that is readable by the Ender 3, and take a glance at the scenario of the Ender 3 not detecting the SD card at all regardless of the file type.

Why Is My Ender 3 (Pro/V2) Not Reading STL Files? 

If it’s your first time printing with your Ender 3, the fact that the 3D printer is not reading the STL files, especially considering that the STL files contain the 3D model data that determines the object the 3D printer will be producing, can come as a surprise.

First of all, let’s start by saying that it’s entirely normal for your Ender 3 not to read STL files, as the STL files are not designed for the purpose of conducting the printing process.

In a nutshell, the data in the STL file contains all the necessary information for a 3D model to be displayed and modified digitally, whether you open it in slicer software or CAD software, as long as the software you’re using supports the file type.

On the other hand, the STL file does not contain the data that your Ender 3 requires to conduct the printing process, such as the orders and the positions of the paths your Ender 3 will follow, the printing temperature, and the print speed, and practically anything else.

As a result, even if your Ender 3 had the means to read and interpret an STL file, it wouldn’t have the necessary information to start the printing process, as this information is not attached to the model but controlled by the user instead in a case-by-case basis due to its dependence on factors that are entirely unrelated to the model itself.

How to Convert STL Files to the G-Code Format That the Ender 3 (Pro/V2) Can Read?

Fortunately, converting the STL files that your Ender 3 cannot process to a format known as G-code, that all 3D printers, including the Ender 3, can read, is a fairly straightforward process that is done automatically by computer software.

To convert an STL file to the G-Code format that your Ender 3 can read, you will need to import the file in a slicer, such as Cura, perform the necessary configuration of the parameters that aren’t a part of the model itself (print temperature, print speed, etc.), and finally slice the 3D model.

The slicing process will create a G-code file, which is a list of individual G-code commands that your Ender 3 will execute in order, with each line containing the necessary directive for a single step of the printing process, and this time, including the information that is not related to the 3D model itself.

This way, your Ender 3 will have all the necessary information required for the printing process in a simple format that requires the execution of a single instruction at a time, allowing the 3D printer to operate with a simple microcontroller and not require a more advanced processing unit.

Ender 3 (Pro/V2) Not Detecting the SD Card – What to Do?

In some cases, it’s possible for the Ender 3 not to recognize the SD card at all, even if you have the correct file type saved to it for the printing process, which is an entirely different problem requiring a specific solution.

Your Ender 3 may fail to detect the SD card you insert into it due to various reasons, with an incorrect filesystem, an incorrect partition table, a too high storage size, and a defective SD card being the most common culprits that cause the problem.

Our primary recommendations to ensure that your Ender 3 can correctly read the SD card would be to use an SD card that is 8GB in size at most, switch the SD card’s partition table to MBR, and format it with the FAT32 filesystem, which is a solution process that is known to fix the issue in almost every case.

If the SD card still does not work after correctly performing the steps above, it’s highly likely for the SD card reader of your Ender 3 to be the problem.

Wrapping Up

Even though the STL files are indeed 3D model files that have the necessary data to display a 3D model on the screen of your computer, the Ender 3 or any other 3D printer will not be able to read these files, which is intended.

To quickly recap, the firmware of your Ender 3 does not support reading an STL file, as even though the file has data about the 3D model, it doesn’t carry any information about how the 3D printer will conduct the print, essentially meaning that the STL file has insufficient data.

The file format your Ender 3 requires for the printing is called gcode, which you obtain by putting the STL file through a slicer, such as Cura. The gcode file format essentially contains lines of G-code commands that your Ender 3 will execute in order, resulting in your 3D model being printed.

Happy printing!