Auto leveling with two independent Z steppers?
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Then you need to change the description at the end of the M558 command as YOU have it listed as an IR sensor.
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If X ZERO is at the Low end of the X axis (i.e the left side of the bed) and the lead screw is further to the left of that then the FIRST number needs to be a negative from the the ZERO point. this is MY code that IS WORKING.
M671 X-40:440 Y206:206 S2 ; Lead screw positions at right and left of the X axis
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thanks, you use this on a blv cube?
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Ok, independent leveling works, 1 problem left after doing all this is the fact that the printer does not recognized the whole bed size? After G32 it does z level dance twice and reports back level correction. After that it goes wrong it homes not in the center of the bed anymore. But in the back left. And the mesh leven happens in that left back part. During mesh leven it errors telling certain points could not be reached.
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I use the basis for this on many printers.
You need to play with your axis maxima & minima and define your grid to where the PROBE can reach NOT to where the nozzle can reach.
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@Caveman said in Auto leveling with two independent Z steppers?:
Ok, independent leveling works, 1 problem left after doing all this is the fact that the printer does not recognized the whole bed size? After G32 it does z level dance twice and reports back level correction. After that it goes wrong it homes not in the center of the bed anymore. But in the back left. And the mesh leven happens in that left back part. During mesh leven it errors telling certain points could not be reached.
Perhaps best to start a new thread. Include your entire config.g and homing files.
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@Phaedrux, I think that the dual Z leveling procedure requires also an additional Z homing, after the leveling.
If I do center point Z homing with bltouch and then run a mesh probing, the mesh is as expected. If instead I do center z homing, then dual Z leveling (this is a new step) and then mesh probing, the mesh is sometimes elevated 0.2 - 0.3mm, as the dual z leveling introduced Z offset. A second Z homing at the center fixes that.
Does this make sense?
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Yes that makes sense. When you correct for tilt the z height has changed.
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@Phaedrux said in Auto leveling with two independent Z steppers?:
Yes that makes sense. When you correct for tilt the z height has changed.
But wait, surely David took this into account when writing the firmware? Logically when the firmware homes all axis it stores that data (including the Z offset at the centre of the bed) then it carries out the requested "leveling" of the X gantry along the X axis which is now being probed at the pre determined three points (up until the point it starts probing the mesh)
Surely logic would dictate that as the firmware already knows where it is in space (because it has homed) and now has a virtual picture of those three points along the X axis and the fact that those three point are going to be of an already fixed (level) height (unless the bed has been physically moved)
And Because we have already set the dive height number of where any probe triggers for example in the centre the probe triggers when the nozzle is 0.041mm from the bed, then when the probe goes to the first left probe point, it is still going to trigger when the nozzle is 0.041mm from the bed because of how the nozzle is physically mounted.
To me it must get the difference in knowing the trigger point in the centre, then when the height it lifted up then it compares how much it had to drop down (plus or minus) at the SAME trigger distance above the bed, and then it does exactly the same at the second leveling point along the X axis and compares all Three measurements and extrapolates the difference, and adjusts itself accordingly, I don't think that physically the z offset in the centre of the bed is physically going to change due to "leveling" along the X axis.
Is it not going to plot along all THREE points "joining the dots" and follow the terrain of the bed between point 1, the centre (which is the home/datum) and point 2 instead of looking at it as a straight line between points 1 & 2 ?
Of course if its its not like that maybe @DC42 can please explain how it does take its measurements and how the "levelling" effects homing.
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The leadscrews are adjusted to try to make the height errors at the points probed in bed.g as small as possible. That's not the same as setting zero height error at bed centre, which is what you normally do when homing Z using a Z probe.
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@dc42 said in Auto leveling with two independent Z steppers?:
The leadscrews are adjusted to try to make the height errors at the points probed in bed.g as small as possible
This is consistent with the dictionary. 'leveling' is merely making something horizontal. I was thinking of it as dual z homing and hence my initial confusion.
I think it worth clarifying in a few places in the documentation that the required sequence is home/level/home, and then an optional mesh.
When I run just home/level/mesh, I got a warning about Z offset.