Unsolved mesh bed compensation not applying correct corrections
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so an update to the issue. spent all of this evening re checking that the machine is as square as reasonably possible and have levelled the bed to as close as i can get it to perfectly flat
but now when i go to load up the height map it gives me the error:
G29 S1
Error: G29: Failed to load height map from file heightmap.csv: failed to read line from fileat this point i dont really need mesh compensation as get ting very nice first layers without the mesh but for completions sake i want to get everything working as intended and iron out the few areas that are slightly more squashed than others on the first layer. should i try reducing the number of probed points to try and get it to accept the height map? or just any steers in the right direction would be highly appreciated.
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Can you upload that Height map. CSV?
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@Phaedrux heightmap.csv there you go mate, appreciate the help so far!
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I don't see anything in particular wrong with that file. Try deleting it from the SD card and re-running G29
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so deleted the file and reduced the number of probe points and it seems to of accepted the file now,but it still seems to be not applying the mesh correctly. there are inconstant very small gaps between the extruded lines in a couple of patches on the bed so that leads me to believe that something i have borked up in my config. ive checked my extrusion multiplier and calibrated my e steps so at this stage it must be something in my config or associated files.
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@necrorat said in mesh bed compensation not applying correct corrections:
inconstant very small gaps between the extruded lines in a couple of patches on the bed
that is either a problem with under extrusion or backlash in your printer. not a problem with mesh bed leveling.
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@Veti 90% of the bed layer is perfect there are two patches where the gaps are observed so if it was under extrusion or backlash would it not be consistently like that all over the bed with mesh levelling working as it should?
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post a picture
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@necrorat said in mesh bed compensation not applying correct corrections:
The image seems to show a bowed gantry. What areas are not touching the bed?
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not the best pictures but best i can do at the moment.the main area is the region 3 threes what appears to be a island where the print head is too far from the bed
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Where are those locations in relation to the heightmap?
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I see you're using the BLTouch. You can attempt to get a bit more accuracy and repeatability out of it by modifying your M558 a bit.
M558 P9 H5 F60 T6000 A10 R0.75 S0.003 B1Slower probe speed, with repeated attempts if 2 consecutive probes don't match to within a tighter tolerance. Probing will take longer because of the slower dive height and it will do at least 2 probes per point. But you will be far less likely to get outliers.
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@Phaedrux so 1 is the rear right of the height map and 3 is the front centre on the height map. sweet thanks for the tip ill change that out and give it a try probably wont be till tomorrow till ill get to try it now though.
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can you measure the z trigger heigh at different positions?
it is possible that you have different trigger heights based on position.
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@Veti so i measured the z trigger height and it didn't vary by more than 0.005mm at each of the 9 points i measured at, it did vary from point to point but thats kinda the point of bed levelling isn't it ?
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@necrorat said in mesh bed compensation not applying correct corrections:
so i measured the z trigger height and it didn't vary by more than 0.005mm at each of the 9 points i measured at, it did vary from point to point but thats kinda the point of bed levelling isn't it ?
no the z trigger height has to be constant across the entire bed otherwise you have the effects that you are seeing.
to clarify i am not refereing the the result of a G30 but the valude of of Z for G31 when calibrating it. -
@Veti just ran though a 3x3 grid to check and i am consistently getting 2.31 for the trigger height
01/02/2020, 15:16:27 M98 P"0:/macros/probe test"
Current reading 0, threshold 25, trigger height 2.31, offsets X-29.5 Y11.4 -
@necrorat said in mesh bed compensation not applying correct corrections:
01/02/2020, 15:16:27 M98 P"0:/macros/probe test"
does that macro do this?
https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe#Section_Calibrate_the_Z_probe_trigger_height -
@Veti ive wrote it as this to probe 3 times per spot:
G1 Z10
G30 S-1
G1 Z10
G30 S-1
G1 Z10
G30 S-1 -
so have just run it again and i am getting quite a large variance now in the region of 0.11mm is this a mechanical issue? the machine is set up on linear rails and i have ensured that they are as square and parallel as possible
