Unsolved mesh bed compensation not applying correct corrections
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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
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@necrorat said in mesh bed compensation not applying correct corrections:
G1 Z10
G30 S-1
G1 Z10
G30 S-1
G1 Z10
G30 S-1that determines repeatability, but does not determine z probe trigger height as you do not determine z=0 before probing as described in the above linked document
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@Veti so do i have to go though the full calibration procedure for each point that i probe on the bed?
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@necrorat
do one at the point where the lines where ok and one where the lines where not ok -
@Veti so just did a test over 5 point and theses are the results :
2.064
2.068
2.066
2.059
2.046 -
thats a lot different than your original trigger height of 2.31
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@Veti i have been tinkering with the frame and alignment all day. gonna probe the bed one last time then try another print
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Sry to bring up that old post again.
@necrorat Did you find a solution or the reason why the meshbed compensation didn't apply?
I have the same issue.
