You spent two hours tramming the bed manually with a sheet of paper, started a print, and the first layer is perfect in three corners and transparent in the fourth. Manual bed leveling is a skill, but auto bed leveling is a tool — and installing an ABL probe correctly transforms a printer that needs constant adjustment into one you start and walk away from.
BLTouch vs CR Touch: Which to Choose
The BLTouch and CR Touch are functionally identical in operation: a solenoid-driven pin extends, touches the bed, retracts, and the probe sends a trigger signal to the control board. The differences are in build quality and wiring:
| Feature | BLTouch (v3.1) | CR Touch |
|---|---|---|
| Probe mechanism | Metal pin with plastic body | Metal pin with metal body |
| Repeatability (standard deviation) | 0.005mm typical | 0.005-0.01mm typical |
| Wiring connector | 5-pin Dupont (3 for servo, 2 for endstop) | 5-pin JST (same pin functions) |
| Cable length | 1m or 1.5m options | 1m fixed |
| Price | $35-40 | $30-35 |
| Pin replacement | Replaceable plastic pin ($5 for 5) | Replaceable metal pin ($10 for 2) |
| Mounting bracket included | Universal bracket with hardware | Printer-specific bracket (Ender 3, CR-10, etc.) |
The CR Touch is Creality’s in-house alternative to the BLTouch. It uses a metal body that survives nozzle crashes slightly better, but the BLTouch’s lighter plastic body rings less during high-speed probing. For most users, the choice comes down to wiring convenience — the CR Touch’s JST connector plugs directly into Creality 32-bit boards (4.2.2 and 4.2.7) without adapter boards.
Step 1: Physical Mounting
Mount the probe to the left or right of the hotend, never in front (interferes with part cooling duct) or behind (cable routing interferes with the gantry at max Y). The probe tip must sit 2-3mm above the nozzle tip when retracted and extend 3-5mm below the nozzle tip when deployed. If the probe tip does not extend below the nozzle, the nozzle will crash into the bed before the probe triggers — destroying your bed surface and possibly the probe.
Most mounting brackets set this height correctly out of the box. Verify with calipers: deploy the probe (M280 P0 S10 in terminal or BLTOUCH_DEPLOY in Klipper), measure from the probe tip to the bed with the nozzle touching the bed (Z=0). The measurement should be 2-4mm.
Step 2: Wiring — Board-Specific Pin Mapping
The BLTouch/CR Touch uses 5 wires in two groups:
– Servo group (3 wires): 5V (red), GND (brown), and control signal (yellow/orange). Powers the solenoid and receives deploy/stow commands.
– Endstop group (2 wires): GND (black) and signal (white). Sends the trigger pulse when the probe touches the bed.
Creality 4.2.2 / 4.2.7 boards (32-bit, dedicated BLTouch port):
The 5-pin port is labeled and keyed. Plug the CR Touch directly — the pinout matches. For BLTouch, wire per the port label.
SKR Mini E3 boards (dedicated probe port):
The 5-pin probe port near the Z-endstop connector. Pinout (left to right): GND, 5V, PA1 (servo), GND, PC14 (endstop). Match wire functions to pins.
Wiring adapter boards (for older 8-bit boards):
If your board lacks a dedicated probe port, use a Pin 27 adapter board that plugs into the LCD header to free up a pin for the servo signal. The endstop wires connect to the Z-min endstop connector in place of the physical Z-endstop switch.
Critical wiring check: Never swap 5V and GND. The probe’s microcontroller runs on 5V — feeding reversed polarity destroys it instantly. Triple-check with a multimeter before powering on.
Step 3: Firmware Configuration — Marlin
For Marlin firmware (most common on Creality and budget boards), uncomment or add these lines in Configuration.h:
#define BLTOUCH
#define NOZZLE_TO_PROBE_OFFSET { -40, -10, 0 } // X, Y, Z offsets — measure these
#define PROBING_MARGIN 10
#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
#define USE_PROBE_FOR_Z_HOMING
#define Z_SAFE_HOMING
#define Z_SAFE_HOMING_X_POINT (X_BED_SIZE / 2)
#define Z_SAFE_HOMING_Y_POINT (Y_BED_SIZE / 2)
The NOZZLE_TO_PROBE_OFFSET values must be measured on your specific printer:
– X offset: Distance from nozzle center to probe tip in X axis. Negative if the probe is left of the nozzle.
– Y offset: Distance from nozzle to probe tip in Y axis. Negative if the probe is in front of the nozzle.
– Z offset: Distance the nozzle must move down after probe triggers to touch the bed. Always negative. Start at -2.5mm and tune with the first-layer test square from our bed adhesion guide.
After flashing, the printer menu gains a “Bed Leveling” section with options for probe deploy/stow test, Z-offset wizard, and mesh leveling.
Step 4: Firmware Configuration — Klipper
For Klipper, add to printer.cfg:
[bltouch]
sensor_pin: ^PC14 # Probe trigger pin (check board pinout)
control_pin: PA1 # Servo control pin
x_offset: -40 # Negative if probe is left of nozzle
y_offset: -10 # Negative if probe is in front of nozzle
z_offset: 2.5 # Initial rough offset — calibrate with PROBE_CALIBRATE
speed: 5.0
samples: 2
sample_retract_dist: 3.0
[bed_mesh]
speed: 120
horizontal_move_z: 5
mesh_min: 20, 20
mesh_max: 200, 200
probe_count: 5, 5
algorithm: bicubic
After adding the configuration, run PROBE_CALIBRATE in the Klipper console. This command homes Z using the probe, then allows you to manually lower the nozzle to the bed using the paper test. Accept the position, and Klipper calculates and saves the Z-offset.
Step 5: Probe Offset Calibration
The X and Y probe offsets determine where the mesh grid points are probed relative to the nozzle. An incorrect X/Y offset means the mesh compensation applies at wrong positions — the printer compensates for a dip that is 5mm away from where the nozzle actually is.
Measuring X/Y offset:
1. Home the printer
2. Place a piece of blue tape on the bed
3. Lower the nozzle until it just touches the tape, leaving a small indent
4. Raise Z by 5mm
5. Deploy the probe and jog it to the same indent
6. The X and Y distances the probe had to move are your offsets — enter them into firmware with correct sign (probe-left-of-nozzle = negative X)
Measuring Z offset (Marlin and Klipper):
1. Home Z using the probe
2. Place a sheet of standard printer paper under the nozzle
3. Lower the nozzle in 0.1mm increments until the paper drags with resistance but can still be moved
4. The Z position shown is your Z offset — enter it as a negative value (e.g., -2.75)
ABL Probe Installation Reference
| Configuration Step | Common Value (Ender 3) | How to Verify |
|---|---|---|
| X offset | -40 to -45mm | Tape indent method described above |
| Y offset | -8 to -12mm | Tape indent method |
| Z offset | -2.0 to -3.5mm | Paper test + first-layer square |
| Probe speed | 3-5 mm/s (Marlin), 5.0 (Klipper) | Faster probing reduces accuracy — stay under 10 mm/s |
| Sample count | 2 (Klipper default) or 1 with multiple probing | 2 samples with tolerance check catches debris on bed |
| Mesh points | 3×3 minimum, 5×5 for beds over 200×200mm | 7×7 for large beds with known warp |
| Probe deploy temperature | Any temp — BLTouch is rated to 50°C ambient | Do not mount probe in an enclosure exceeding 50°C |
Common BLTouch/CR Touch Installation Failures
Mistake 1: Not removing or disabling the physical Z-endstop switch
The consequence: With the probe connected to the Z-min endstop pins, the original Z-endstop switch is still plugged into the same circuit. When the gantry homes, the physical switch triggers before the probe extends — Z=0 is set to wherever the switch is, not where the bed is. The fix: Disconnect and physically remove the Z-endstop switch. The probe IS the Z-endstop now. In firmware, Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN routes the probe signal through the Z-min circuit.
Mistake 2: Enabling ABL without enabling Z_SAFE_HOMING in Marlin
The consequence: During homing, the probe deploys wherever the print head happens to be. If the print head is at X=0 Y=0 and the probe is mounted with X=-40, the probe deploys off the left edge of the bed into empty space — it never triggers, and the nozzle crashes into the bed as Z continues downward. The fix: Z_SAFE_HOMING forces the print head to the center of the bed before probe deployment. Always enable it when using a probe for Z-homing.
Mistake 3: Failing the probe pin in the deployed position during a crash
The consequence: The nozzle catches the print during a failed first layer. The hotend assembly tilts, bending or snapping the deployed probe pin. The BLTouch stays in an error state (blinking red) and refuses all further commands until power-cycled. The fix: The BLTouch pin is a consumable — keep 2-3 spare pins on hand. Replacement takes 30 seconds: power off, pull the old pin straight out (magnet-retained), insert new pin, power on. The CR Touch pin is screw-retained and slightly harder to replace in the field.
Mistake 4: Mounting the probe with a 3D-printed bracket that flexes during probing
The consequence: The bracket flexes 0.05-0.1mm under the probe’s deployment force. Every touch-off point records a slightly different height because the bracket is at a slightly different angle. The resulting mesh has random noise that looks like bed warp but is actually bracket flex. The fix: Use a rigid metal or injection-molded bracket. If using a printed bracket, print it in PETG or ABS at 100% infill — PLA brackets soften from bed heat over time and eventually droop into the nozzle path.
⚠️ Safety Notice: Firmware modification and probe installation involve working with energized electronics. Always disconnect the printer from mains power before connecting or disconnecting any wiring. Incorrect firmware configuration can cause the nozzle to crash into the bed at full stepper torque, potentially damaging the bed, hotend, and probe. Test probe deployment and retraction via terminal commands (M401/M402 in Marlin, BLTOUCH_DEBUG in Klipper) before running a homing cycle. Follow 2026 electrical safety standards applicable in your region.
For Klipper users, our Klipper firmware migration guide covers the complete transition from Marlin — Klipper’s probe handling is simpler and more configurable than Marlin’s compile-time offset approach.
After installing the probe, recalibrate your Z-offset with the first-layer test from our bed adhesion guide. The probe gets you to within 0.01mm of the bed surface — the Z-offset determines whether that is close enough.
The CR Touch auto bed leveling kit ships with a rigid metal mounting bracket, pre-terminated JST wiring, and 2 spare probe pins — a 20-minute bolt-on upgrade for any Creality Ender 3, CR-10, or Ender 5 series printer. Available at uavmodel.com.