G33 Begin height question


After fiddeling around and doing leveling stuff i changed the Z-Max probe bed distance in Eeprom. 
G32 started a the desired height, in my case 3 mm (i know its close but the z-probe speed is slow)
after that i started G33 and saw that the referenced height was 20 mm, it took more than 1,5 minutes to do 1 probe point. 

Because i had some time to spend i was looking in the Firmware if this height was somehow fixt. 
i stumbled on these lines 

bool Distortion::measure(void) {
    fast8_t ix, iy;

    float z = RMath::max(EEPROM::zProbeBedDistance() + (EEPROM::zProbeHeight() > 0 ? EEPROM::zProbeHeight() : 0), static_cast<float>(ZHOME_HEAT_HEIGHT)); //EEPROM::zProbeBedDistance() + (EEPROM::zProbeHeight() > 0 ? EEPROM::zProbeHeight() : 0);
    Com::printFLN(PSTR("Reference Z for measurement:"), z, 3);

now if i read it correctly the refence z height = z probebeddistance (3mm in my case?) + z probe height, unless lower than 0 then add 0 (in my case 1,377mm), then the last value is 20mm 

in configuration.h  ZHOME_HEAT_HEIGHT was mentioned and had the value 20, because in the rest of firmware this value is used for allot of stuff i didn't want to fiddle with it especially that my printer is running good right now 

hope somebody can enlighten me, that wil be great 


  • That is the value set by Printer::prepareForProbing(); so you can not change it. You can set a different ZHOME_HEAT_HEIGHT if you like. That is meant to protect surface from hot extruders as some surfaces will get destroyed otherwise. There is no reason to not reduce it, so set it e.g. on 3mm instead and the function will start much lower.
  • thanks for the quick answer 
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