Z height inconsistency



  • I have as much as 1mm difference in my z trigger hight. Is there a specific hight i should use for my capasitive sensor. Im running a glass build platform.
    Does a low or high sensitivity work better as far as accuracy. Any ideas ???



  • So what i found was on sod of tje x gantry was slightly to tight i also brought the sensor down with in 2mm of the nozzle and tirndndown sensitivity considerably
    This seems to have cured it for now.
    Any input appreciated 😁👍



  • @ziggymanpopo said in Z height inconsistency:

    So what i found was on sod of tje x gantry was slightly to tight i also brought the sensor down with in 2mm of the nozzle and tirndndown sensitivity considerably
    This seems to have cured it for now.
    Any input appreciated 😁👍

    I was curious as to your solution but I don't understand "was on sod of tje x gantry was slightly to tight" or "and tirndndown sensitivity".

    Can you elaborate please?

    Thanks.

    Frederick



  • My capasitive z sensor has a sensitivity setting on the top .. "small trip pot. " This changes the sesitivity of the probe and ofcourse the height since sensitivity relates to how soon the sensor trips
    I helieve that the more sensitive the probe the higher it will trip and the more error in repeatability
    The closer to the nozzle hieght though ...to the probe the less error factor ant the less offset
    Please share you veiws. Because i can certainly be wrong.
    What would be the perfect hieght for my sensor ???
    Where do we get the specifics for what adjustment physically...!! will give me the most accurate results.



  • Assuming this is an inductive probe, you should allow for some clearance to the bed but not be too far off. The PINDA probe used on Prusa printers are calibrated to trigger at a 2mm distance to the print surface.

    One way to adjust this is to manually jog the nozzle to just touch the bed, and with a precisely 2mm high object adjust the probe so the object slides between the bed and probe, barely touching either, and then fixing the probe in place. When that's done you can adjust sensitivity with the trim pot (usually there is an LED that tells you when the probe triggers.

    PINDA probes also have a thermistor to compensate for temperature related sensitivity changes, which you can use on Duet boards with RepRapFirmware 3.



  • Pinda probe is a prussa product correct???.. and
    I have a capasitive sensor since i use a glass build plarform
    Im also wondering whats the expected accuracy range for my sensor.
    After several probes i get this for readings
    2.91
    3.93
    3.82
    3.13
    2.94
    2.84...ect.

    I would wxoect really more accuracy than that right?? Ir am i exoecting too much ??



  • Ops that should 293 not 393



  • Man my dyslexia is acting up
    Thies are the correct triger hieght being returned
    2.85
    3.03
    2.82
    3.13
    2.94
    2.84
    2.81
    3.00
    2.95....ect. a spread between 2.82 and 3.13mm
    What normall???,



  • PINDA is the prusa product but similar probes exist in aftermarket. According to the wiki, capacitative probes have low precision / repeatability (see https://duet3d.dozuki.com/Wiki/Choosing_a_Z_probe).

    If you heat the bed before probing, you may get improved results by switching off the bed heater during probing (see M558 B parameter).


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