mesh compensation too aggressive?
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@gloomyandy taper is imprecise anyways because it also doesn't compensate flow for any of the changes.
Personally, I haven't seen an overly aggressive mesh compensation on my various machines. If anything, taper applied at the first layer should lead to less compensation than the mesh does.
If I were to adjust for the taper compensation, I would modify my mesh so it is increased by the taper reduced factor applied, and then load the normal mesh on second layer. But that sounds like work, and since we practically are talking about 5 percent or less of something like 0.4 (so 0.02mm), I would assume my mechanical and extrusion precision is not good enough for an actual effect on the resulting part quality.
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@gloomyandy whether or not the board can tell if it's the first layer or not is not my problem. It makes no sense not to track the exact measured offset for the first layer. That way you get the cleanest possible first layer.
Hi, would you like to save $0.50 on that $5.00 sandwich today? Ok, please pay me $4.75.
That is effectively what is happening. And although the documentation, in the fine details, does indicate that that is happening. It's wrong. You should be able to understand the documentation for this feature in one sentence.
It shouldn't be so complicated that the user has to calculate their own heatmap to offset for the taper adjustment on the first layer.
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I think you will find that for a useful taper setting that the effect on the first layer is negligible.
Have you been having problems?
Frederick
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@fcwilt yes, it smooshes too much in some areas, and I have a great bed.
But the point is, it is literally impossible to get a perfect first layer if it's not following the contour.
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@gnydick said in mesh compensation too aggressive?:
@fcwilt yes, it smooshes too much in some areas, and I have a great bed.
But the point is, it is literally impossible to get a perfect first layer if it's not following the contour.
I am using 3.4.6 on five different printers and mesh comp works fine. I have verified that it follows the height map exactly.
Perhaps the problem lies in 3.5.x?
Do you set the Z=0 Datum at the same fixed XY position when creating the height map and loading the height map?
Frederick
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@gnydick What happens if you run the same test print without a taper set? Is the first layer any better? Can you post a screenshot of the mesh display from DWC including the stats (min/max deviation etc.).
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@fcwilt I'm not following what you mean about the z=0.
How are you confirming it's following it exactly, considering the source code and documentation show the first layer is subject to taper, making it impossible to follow the map exactly.
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@gloomyandy I'll try it and let you know.
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@gnydick said in mesh compensation too aggressive?:
I'm not following what you mean about the z=0.
When you use your Z probe by executing a G30 command at a fixed XY location (always the same) you are setting the Z=0 Datum.
How are you confirming it's following it exactly, considering the source code and documentation show the first layer is subject to taper, making it impossible to follow the map exactly.
I created a heightmap using a text editor that had deviations ranging from 0 at the left edge to 100mm at the center then back to 0 at the right edge. With these large values it was easy to move the nozzle to various X positions and measure the Z position of the nozzle.
In any case the amount of taper adjustment applied to the first layer is very little.
Frederick
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@fcwilt I think you're asking me if I home my Z axis at the same place every time. Yes.
What I always do is home, then tram, and then use the printer. I don't home again after that. Maybe I should.
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@gnydick yes, you need to rehome Z after tramming because the plane may have shifted and with that Z is out of whack.
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@gnydick said in mesh compensation too aggressive?:
I think you're asking me if I home my Z axis at the same place every time. Yes.
Yes and no.
Since I don't home Z using the Z probe I always speak of setting the Z=0 Datum rather than homing Z.
Frederick
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@gnydick It is also a good idea (assuming you use a probe to set Z=0) to home so that the probe is over one of the points in the bed mesh. If you do that then that point should read 0 in the mesh (or very close to it), if that is not the case then there may be a problem with the mesh (or possibly there is a problem with repeatability of Z homing).
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@gloomyandy good advice