Bed height mapping error on 1st coordinate

Well i either have a really bent corner at 20,20  on my bed(it looks flat too the eye) or something is messing about
bed levelling results, tested severall times.

X: 20.00 60.00 100.00 140.00 180.00

y:180.00 14.79 14.81 14.77 14.66 14.67
y:140.00 14.65 14.70 14.69 14.60 14.59
y:100.00 14.55 14.62 14.64 14.58 14.62
y:60.00 14.62 14.68 14.71 14.66 14.72
y:20.00 5.49 14.78 14.82 14.78 14.83


  • What is the starting height? Looks like it went on first probe more up then it should have done and kept distance on the others.

    What firmware version (date) are you using? What is that start/end script for z probe?
  • edited February 2017
    Printer is a prussa I3 clone
    New DEV firmware from Feb 4 installed about 1 hour before my post. was allso getting same results with previous FW.
    Using inductive probe on Z min with a Z max switch
    No start or end scripts used
    Z probe height =0.7
    max z probe-bed dist = 5
    distance to untrigger probe = 4

    sequence of events
    G28   ;Home X Y Z   (Z home =Z150)
    G1 Z10
    then use measure bed height in host tools menu

  • Just doing some experiments and observed that what ever height i start the probing from,lets say Z20, it will probe the 1st coords (20,20) then raise Z5  it will then ramp up to Z20 while it travells to 2nd coords. All remaining probe s will raise to Z20 before moving to next coords 
  • Ok, I see what what is wrong. You need to start at 5mm and it would work.

    What happens is that first point enables z-probe and part of that is ensuring height is smaller then max z probe-bed dist+z probe height+0.1 whcih is why it measures that low value. For later points the host keeps sending Z=20 as z position and since the height adjustment only happens at first move it is not corrected again.

    So only solution is to start below that limit height so you do not get corrected. Need to add that to z-probing tutorial!
  • edited February 2017
    tyvm, starting at Z5 sorted that problem.
    Is running the bed height map from tools menu supposed to store the results in eeprom, if i do G33 L0 afterwards
    all coords show Z0

    Ummm, tutorial? what!!! where !!!! :)
  • No, host bed map is independent of G33. G33 would measure and store.
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