Height map worse than actually is
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if there is any twist and the probe is not mounted directly under the rail this could result in significant variance as well even without significant deflection down.
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@nhof could you better explain, please? Do you mean twist on the X axis? Indeed my probe is around 6cm away of the axis (in the -Y direction - I'll take a picture when I get home), but I don't understand how it could amplify the error by a factor of 2.
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I also configured the probe offset to reflect its actual position.
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@Cartola said in Height map worse than actually is:
could you better explain, please? Do you mean twist on the X axis?
he means that the hotend is not plane. it rotates slightly as it moves.
as it moves the nozle goes up while the probe does down for example.
this will give you different readings based on the positon that the carriage is at. -
@Veti, got it.
The hotend and the probe is rock solid mounted between them, but I don't know how to "prove" that. Here are some pictures of my hotend:
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its not the bltouch mount but the entire carriage.
that hermera is quite heavy.
the further it moves to the middle of the bed the further it pushes the lower rod to the back.
that causes the bltouch to move in relation to the nozzle by rotation. -
@Veti I understood the theory, but the rotation can't be that high... I think... 2 * 8mm tempered steel high quality rods. How could I confirm if that is what is happening? Also, the deflection happen equally on X and Y axis.
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@Cartola said in Height map worse than actually is:
How could I confirm if that is what is happening? Also, the deflection happen equally on X and Y axis.
remove the hermera and try with just a probe.
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@Veti ok, I will try.
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@Cartola said in Height map worse than actually is:
2.03 (2019-06-13b2)
Likely unrelated, but you should probably update your firmware, Lots of bug fixes between 2.03 and 2.05.
Have you tried an actual test print to highlight the bed surface and see if the heightmap is actually representative of reality? The curve is exaggerated to highlight the shape.
Print this twice, once with mesh compensation enabled and once with it disabled. Should give you a good idea if things are working properly.
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Hi @Phaedrux, I added all the versions "just in case"
I could verify the difference using paper, for sure printing would give me the same result.
For everybody that help me - I removed the Hemera and re-run the mesh. Now I don't see the bad results, only the expected axis reflection. You were right! I will re-draw the BLTouch support for Hemera/Hevo to align with the nozzle in the Y axis, this way, even with some rotation, having the BLtouch aligned won't increase the error. Too bad I will lose some print area on X
I hope to have everything fine and uploaded to Thingverse or somewhere else soon!
Thank you all! I will return once I have the updated version.
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@Cartola
i started off with a hevo as well, but since redone the entire thing.
the smooth rods were always a source of small inconsistencies.
in the end i used the motion setup of the blv cube. its a lot more sturdy and would support the hermera as well.
