BL Touch Antclabs | 3D Printer Auto Bed Level Sensor


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The BL Touch is an Auto Bed Leveling Sensor for 3D Printers that can precisely measure the bed offset from your extruder to your print surface. It can greatly improve the printing precision of your 3D Printer and help 3d prints stick for better bed first layer adhesion.


BL Touch Information

BL Touch is a 3D Printer auto bed leveling sensor that can detect any print bed surface. Antclabs is the original creator of this high precision bed sensor. The sensor is compatible with most mainboards and firmware. It’s very easy to operate and will improve first layer bed adhesion.

Mounting the BL Touch Sensor

When mounting the bl touch 3d printer sensor it’s important to be within the specified distance from the build plate. Mounting it too close to the print bed or too far can result in bad print adhesion or even damage your 3d printer.

bl touch dimensions

There are many ways to mount your sensor to your 3d printer. Search here on Thingiverse to find the best mount for your 3D Printer model.

BLTouch wiring

There are 2 wire sets with connectors that come with the BL Touch Sensor. One is for the power and the other is for the sensor trigger.

Power Connector Wiring

BROWN    -> (-) GROUND

RED          -> (+) 5V Power


EndStop Connector Wiring


WHITE  -> Zmin Pin

You can find more detailed wiring instructions with image examples here:

Configuring Marlin Firmware

Once you have your new probe sensor connected it’s time to enable it in your 3D Printers firmware. In this example we will demonstrate how to do this with Marlin 1.1 Firmware. If you are just starting out or have never configured marlin check out this great tutorial for beginners to setup Marlin: Marlin 1.1 Beginner Guide for 3D Printer Firmware

To configure your probe open the configuration.h file and scroll down to around line 730

uncomment #define BLTOUCH to enable the probe in your firmware settings.

Next define the offset of your bltouch from your 3d printers extruder nozzle. To do this it’s best to have a nice pair of calipers for accurate measurements. Here you’ll want to measure your X and Y Offsets and then enter then in lines 779 and 780.

#define X_PROBE_OFFSET_FROM_EXTRUDER 10 // X offset: -left +right [of the nozzle]
#define Y_PROBE_OFFSET_FROM_EXTRUDER 10 // Y offset: -front +behind [the nozzle]

Once you have this dialed in run the G28 Auto Home command and test to make sure everything is working.

Next after homing move your extruder’s Z height to 0 and then test with a piece of paper that the nozzle is the correct distance from the build plate. You can fine tune the the Z-Height through your slicer software or through line 881.

#define Z_PROBE_OFFSET_FROM_EXTRUDER 0 // Z offset: -below +above [the nozzle]

Adjust Sensitivity on the Probe

On top of the bltouch there is a set screw. This metal set screw not only holds the pin inside the enclosure but it also acts as the ferrous core for the electromagnet that draws the pin up into the body. If you are having your pin not drop or not retract back up try loosening or tightening the set screw on top in quarter turn intervals to dial it in. Most Antclabs authentic bl touch sensors work right out of the box. Clones can sometimes be difficult to setup or may need more adjustments for proper operation.