We can all agree that troubleshooting is a vital part of the 3D printing process, especially considering that with so many different factors that go into a successful 3D print, the chance of an error occurring also increases naturally.
Perhaps the most challenging part of troubleshooting the 3D printing process is the appearance of new errors that we haven’t experienced; since solving an issue is all about having prior experience that guides us towards the solution.
Today, we will be talking about the auto-home function of Ender 3 and why this function can sometimes bring the printhead to an area outside of the bed instead of the origin point of the build plate, creating a problem that might cause the printer to print into the air.
So, why does the Ender 3 (Pro/V2) auto home off the build plate?
As the X and Y endstops of the Ender 3 are not exactly at the origin of the build plate, the auto-home function ends up positioning the extruder slightly away from this point; in relation to the position of the endstops.
Moving forward, we will analyze why the Ender 3 auto homes the printhead off the bed and what you can do to correct this behavior to bring the printhead on top of the build plate after the auto-homing process.
Why Does the Ender 3 (Pro/V2) Auto Home Off the Bed?
The issue of the Ender 3 auto-home function bringing the extruder to a point off the build plate is an interesting one, as it’s technically not an issue in the traditional sense.
In a nutshell, the reason behind your Ender 3’s printhead ending up in a position that is slightly distant from the origin of the build plate after the auto-home process is due to the endstops not being located where the build plate’s origin is.
While it may sound like a problem at first, you will be surprised to hear that adding a distance between the endstops and the origin of the build plate is an intended move from the printer’s manufacturers for a very logical reason.
By placing the endstops away from the origin of the build plate, the printer ensures that the printhead can never collide with the build plate after the auto-home process, even in scenarios where the build plate is not level.
As damage to both the printhead and the build plate can occur in the scenario where the two collide, this is definitely a great safety measure from the manufacturer’s side.
How to Correct Ender 3 (Pro/V2) Auto Homing Off the Bed?
As we exactly know what causes the Ender 3 to auto-home the printhead off the build plate, correcting this behavior is one of the less challenging troubleshooting tasks in the realm of 3D printing.
To correct the issue of Ender 3 auto homing off the bed where the printer positions the printhead away from the origin of the build plate, you need to adjust the X and Y offsets, which will allow you to compensate for the difference in distance between endstops and the origin of the build plate.
As there are a few different ways to configure the offsets of your Ender 3, feel free to pick the one that you think is the most effortless.
Setting Offsets with the Ender 3 Interface
The most straightforward way to resolve the issue of Ender 3 auto homing off the bed is to correct the offsets through the interface of the printer, which we have listed the steps for below:
- Navigate to the Prepare menu.
- Run the Auto Home command.
- Navigate to the move axis menu.
- Choose the Move Y option.
- Bring the printhead on top of the origin of the build plate on the Y-axis.
- Repeat step 5 for the X-axis.
- Run the Set Home Offsets command in the Prepare menu.
If you set the offsets successfully, you should hear a double beep indicating that you have saved the configuration.
As the printer will only keep the configuration you have done in the volatile memory, ensure that you save the changes to the EEPROM with the Store Settings (M500) command to make this configuration permanent.
Setting Offsets with G-Code
If you can communicate G-code commands directly to your Ender 3 (with software such as Pronterface), you can configure the offsets and fix the auto homing issue with G-code.
To configure the offsets with G-code, you can use the M206 (Set Home Offsets) command with the X and Y parameters that correspond to the offsets of the X and Y axes.
Here is a small example of the usage of the M206 command:
M206 X10 Y20
In this example, you would be shifting the print area 10 millimeters to the left with the X10 parameter and 20 millimeters to the forward with the Y20 parameter.
Settings Offsets by Modifying Firmware
While a less practical solution, you can also hard-code the offset values directly to the firmware and flash this updated version to your Ender 3.
Here is how you can hard-code the offsets in the case of Marlin Firmware:
- Open the “Configuration.h” file with your favorite text editor.
- Find the lines “#define X_MIN_POS” and “#define Y_MIN_POS” which correspond to the X and Y offsets.
- Replace the 0 next to the lines with the values that compensate for the distance.
- Re-flash your printer with the modified firmware.
Ender 3 Auto Home Too High or Too Low – What to Do?
Similar to the Ender 3 auto homing off the bed, which often takes place in the Y-axis, there are times where the auto home function brings the extruder to somewhere that is too high or too low in the Z-axis.
To fix the issue of the printhead of your Ender 3 ending up at a place that is either too low or too high after running the auto-home command, you will need to ensure that the bed is level and reconfigure the Z-offset value accordingly.
Since the issue can also be due to mechanical fault, where mispositioned Z endstops cause the printhead to end up at the wrong position, it’s also a good idea to check the endstops if reconfiguring the Z offset didn’t solve the issue.
While the Ender 3 sending the printhead off the bed due to running the auto-home function can definitely be an annoying problem to face, it’s actually an action the printer performs for a good reason.
To quickly summarize, Ender 3 positioning the printhead off the build plate is actually a result of the endstops having a slight distance from the origin of the build plate, which is intended rather than an issue.
When the endstops are away from the origin of the build plate, the distance removes the chance of the printhead bumping into the build plate after auto-homing in cases where the bed is not level.
Mike started his 3D printing journey with the Anet A8 when it first came out back in 2017, and has been obsessed with 3D printers ever since. Nowadays, he primarily uses his Ender 3 to print functional parts that make his life more convenient whenever possible.