BLTouch and CRTouch: Automatic Bed Levelling Setup

Logan F.

Let the Machine Do the Work

Manual bed levelling is a skill every printer operator should understand, but it’s also one of the most repetitive maintenance tasks in FDM printing. It takes time, needs regular adjustment, and rarely achieves the consistency of a properly configured automatic bed levelling (ABL) system. An ABL probe measures the bed surface before printing and compensates for small variations automatically, helping maintain a consistent first layer across the entire build plate with minimal operator input.

For anyone printing regularly, or running a machine with a bed that drifts slightly over time, an ABL probe is one of the highest value upgrades available.

BLTouch vs CRTouch

The BLTouch (developed by Antclabs) is the original contact based automatic bed levelling probe and remains one of the most trusted options available. Unlike inductive or capacitive sensors, which can behave differently depending on surface material, coatings, colour, or nearby electronics, the BLTouch physically touches the bed using a deployable probe pin to determine the surface position. The result is a consistent and repeatable measurement method that works reliably across a wide range of build surfaces.

The CRTouch is Creality’s version of the same contact based probing system. In practical use, performance between the two is very similar, but the CRTouch is designed specifically around Creality printers and often includes purpose built mounting hardware for simpler installation. Both are excellent options, though the CRTouch is typically the more convenient choice for Creality owners.

Installation Process

Installation begins with mounting the probe to the extruder carriage at the correct offset relative to the nozzle. The X and Y offsets are defined physically by the mount position, while the Z offset is calibrated later in firmware. The probe then connects to the dedicated ABL header on the printer’s control board, which is included on most modern mainboards. Careful attention to the wiring diagram is important here, as incorrect polarity can damage components.

The platform you use determines the firmware setup. In Marlin, this involves enabling BLTOUCH or CRTOUCH, defining probe offsets, enabling it, and selecting an appropriate probe grid size. A 3×3 grid is suitable for smaller beds, while 5×5 provides better compensation for larger or slightly warped surfaces. The firmware is then compiled and flashed to the printer.

In Klipper, configuration is handled through the printer.cfg file by adding a [bltouch] section containing the probe pin assignments and positional offsets. Once configured, the BED_MESH_CALIBRATE process generates a height map of the build surface for automatic compensation during printing. See our firmware guide for context on which firmware approach suits your setup.

Z Offset: Still Important with ABL

ABL doesn't replace Z offset calibration; it uses it. The probe measures the distance between the probe trigger point and the bed; the Z offset tells the firmware how much lower the nozzle is than the probe. This value must be calibrated accurately (see our Z offset guide) for the ABL compensation to work correctly. A common mistake is thinking ABL eliminates the need for any Z calibration, it certainly doesn't. It eliminates the need to repeatedly re-level the bed, but the initial Z offset setup remains essential. Once correctly set up, your printer will deliver consistent, reliable first layers on quality filament every time without operator intervention.