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tools_calibrate.md

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Tools calibrate

An extension to calibrate tool offsets with a nozzle contact probe. Works by bumping the nozzle into the probe form multiple angles to pinpoint the nozzle location.

See Nozzle Align repo for some sensor ideas.

Configuration

See the example folder for a full example.

[tools_calibrate]

pin: GPIO pin (e.g., '^PG11')
     The pin Klipper will monitor to detect a probe trigger.
     - depending on probe may require inversion (ie: !PG11)
     - normally closed: nudge (no inversion)
     - normally open: sexball [microswitch type] (inversion)

spread:               (mm)
    X/Y distance from center for probing sequence
    This defines how far the tool moves during the touch pattern.
    - For large pins (≥5mm), use 3.5-4.0 
    - Larger values = more overtravel, takes longer, safer for larger variance in tools or larger pins
    - Smaller values = less overtravel but may hit too early for large variance tools/large pins
    - Example: a 5mm pin, a 2.5mm spread would touch the pins face. (assuming nozzle = cylinder with 0 width)

lower_z:              (mm)
   Distance to lower the nozzle to hit. (0 -> slides over | 3-4 -> hits silicone sock)
   - 0.1-0.2 = minimal travel, may work, usually cleaner nozzle around here
   - 0.4-0.5 = safer hit margin, possibly less accurate.

travel_speed:         (mm/s)
   Move speed between probes 
   - 0.1-infinity (really doesnt matter that much)

speed:                (mm/s)
   move speed during probes 
   - too slow -> takes forever | too fast -> not accurate enough
   - 0.5-10 would be an average/sane range

lift_speed:           (mm/s)
   speed with which to raise Z

final_lift_z:         (mm)
   Distance to raise Z between/after probing.
   Will also the the distance its waiting above the probe.

sample_retract_dist:  (mm)
   Z retract between samples (Z) 
   - too little -> backlash/doesnt untrigger | too much -> moves up too high/takes longer.
   - 0.2-5 

samples: 
    Number of probe samples to take (usually 3-5)

samples_tolerance:    (mm) 
     Max variance allowed between samples (will retry/abort if exceeded)
     a good probe will work with 0.05, altho increasing it has no effect on results.
     more a "sanity check" then anything else.

samples_tolerance_retries: 
     the amount of times to retry the probing when the sample tolerance has been exceeded.

samples_result:       ['median' | 'average']
     output result method 
     
trigger_to_bottom_z:  (mm)
    Used in trigger calibration calculations.
    Defines Z distance from calibration probe *trigger* to mechanical bottom out.
    sort of like the distance from when your keyboard key registers a hit, to where it actually hits the bottom.
    - 0-3 best calibrated by setting it to 0, 
      running TOOL_CALIBRATE_PROBE_OFFSET and substracting the result from your current probe offset.
    - decrease if the nozzle is too high, increase if too low.

probe: probe 
     (optional name of the nozzle probe to use)

Clean your nozzles

The calibration accuracy is as good as your nozzles are clean. Clean all nozzles thoroughly before calibrating.

Calibrating tool offsets

  • First position the nozzle approximately above the probe - the probe will find the center on it's own within 1-2 mm.

  • The first tool has all offsets to 0 and is used as a baseline for other tools. Run TOOL_LOCATE_SENSOR to calibrate nozzle location for tool 0.

  • For every other tool, run TOOL_CALIBRATE_TOOL_OFFSET to measure the offset from the first tool.

All probing moves and final offsets will be printed in the console.

Calibrating nozzle bed probe.

  • Do the first two steps from above to ensure the probe is precisely under the nozzle.

  • Run TOOL_CALIBRATE_PROBE_OFFSET - to measure Z offset from nozzle triggering the probe to tool's nozzle probe activating.

All probing moves and final offsets will be printed in the console.

Troubleshooting

Probe triggered prior to movement

  • the nozzle is not touching the probe

    • Check if the probe is triggering without touching
    • use a multimeter to check for continuity and if it changes when pressing down on the probe. (or use TOOL_CALIBRATE_QUERY_PROBE to query the status of the probe)
    • Check if the pin is configured correctly. The example configuration is for active low with a pullup. Depending how you have wired it, you might need remove the ^! for active-high.

  • the nozzle is touching the probe - (and could have probed a few times already)

    • Likely the initial position was too far off-center. Try to position it more accurately.
    • The probe is lowered too much and/or not enough sideways - tweak lower_z and spread