Z-Probe Options

The Z-probe module in Smoothieware is used to scan surfaces, calibrate machine parameters, and compensate for non-planar surfaces.

This is essential for features like bed leveling, height mapping, and automated calibration.

Configuration Options

The following table lists the configuration options for the Z-probe module:

Option Value Description
zprobe.enable true Set to true to enable the Z-probe module. This is used to scan surfaces, and to calibrate parameters and compensate for non-planar surfaces.
zprobe.probe_pin 1.28!^ Pin the probe is connected to.
zprobe.slow_feedrate 5 Speed in millimetres/second at which the probe seeks a surface.
zprobe.fast_feedrate 100 Speed in millimetres/second at which the probe does fast moves.
zprobe.return_feedrate 50 Speed in millimetres/second at which the probe does the return after a probe.
zprobe.debounce_ms 1 Debounce the probe pin over this number of milliseconds. Set to 1 or 2 if your probe is too noisy and gives false readings.
zprobe.probe_height 5 Distance above the bed at which the probing is started, once the bed’s height is known.
zprobe.max_z 200 Maximum Z (was gamma_max)
zprobe.dwell_before_probing 0.2 Dwell time in seconds before probing. Useful for piezo Z-probe to avoid false trigger.

Understanding Probe Speeds

The Z-probe module uses different speeds for different operations:

  • fast_feedrate: Used for quick travel moves to the probing area
  • slow_feedrate: Used when actually approaching and touching the surface (for accuracy)
  • return_feedrate: Used when retracting after a successful probe

Using a slower speed for the actual probing ensures more accurate measurements.

Pin Configuration

The probe_pin setting uses special suffixes:

  • ! - Inverts the pin logic (useful for normally-open vs normally-closed switches)
  • ^ - Enables internal pull-up resistor

For example, 1.28!^ means pin 1.28 with inverted logic and pull-up enabled.

Common Probe Types

Different probe types work with Smoothieware:

Mechanical Probes

  • Simple microswitch-based probes
  • Most reliable and simple
  • Configure with appropriate debounce settings

Inductive Probes

  • Sense metal surfaces without contact
  • Only work with metal beds
  • No mechanical wear

Capacitive Probes

  • Can sense various materials
  • More complex to set up
  • Good for glass beds

BLTouch / 3DTouch

  • Servo-deployed pin probe
  • Very popular and accurate
  • Requires specific configuration

Piezo Probes

  • Use pressure sensors
  • Very fast and accurate
  • May need dwell_before_probing setting

Usage

After configuration, use these G-codes:

  • G30 - Single probe at current XY position
  • G32 - Run bed leveling (if leveling strategy is configured)
  • M119 - Show endstop status (including probe)