What is the order of precedence for Z height?
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When my printer is unhomed and cleared of all settings, what is the correct order to run homing, tramming, and loading the height map?
Bed Shape
(140, 140, 0)
- perfect height at center of bed, where I home Z, and no other points on the bed are higher. this is the overall maxima
(5, 5, -.2)
- probe point one is.2mm
below
(5, 270, -.3)
- probe point two is.3mm
below
(280, 135, -.25)
- probe point 3 is.25mm
belowScenario
- my bed is level based on the tangent to the overall maxima. don't ask how, let's just assume it is
- I run
G28
to home all axes -- the printer now sees theZ
height correctly for the center of the bed - I then run
G32
to run bed tramming
At this point:
- What does it do with the 3 lead screw adjustments?
- Where does the printer think Z is?
- I'm 99.99% sure I should run the mesh probing now, right?
- What happens if I
G28 Z
after it's been trammed?
I ask because, what I think I'm observing is that the lead screw adjustments don't take into account that the bed should pivot around where the bed was
Z-homed
, otherwise it will throw everything off. -
I have a macro that is run, by the slicer, at the start of the print.
That last two things the macro does are:
- Execute G30 to set the Z=0 datum
- Execute G29 to load the preexisting height map.
Frederick
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@fcwilt thanks, but not my question. I'm interested in how the controller manages the Z value based on what order you perform the different operations.
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@gnydick I do home all, bed tramming (in my case two leadscrews for Z) then home Z again, though these are all in my bed tramming macro. I think it rotates the plane around X0 Y0; I just tried it and both Z screws moved the same distance, and my bed origin is in the centre, which probably means I don't actually need the second Z home. Which would explain why your home Z position is off after bed tramming, as you're probing Z at the centre, at X140 Y140.
Ian
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@gnydick said in What is the order of precedence for Z height?:
@fcwilt thanks, but not my question. I'm interested in how the controller manages the Z value based on what order you perform the different operations.
Not sure I understand. The firmware tracks any changes to the Z value regardless of the command causing the change.
But the steps I listed insure that at the start of the print the Z value is correct, assuming your probe is configured correctly. The Z value are any other time is not terribly important.
Frederick