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MarlinFirmware / Marlin

Marlin is an optimized firmware for RepRap 3D printers based on the Arduino platform. Many commercial 3D printers come with Marlin installed. Check with your vendor if you need source code for your specific machine.
https://marlinfw.org
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[BUG] bugfix-2.0.x - Auto Bed Leveling not working as expected #13512

Closed guestisp closed 5 years ago

guestisp commented 5 years ago

Hi to all. I'm trying to use a genuine BLTouch sensor (I think v2.1) but without luck The mesh is build properly, auto-home is working as expected, but when running a print, the nozzle is lifter too much even where there is no need to lift it and nothing stick to th bed.

If I disable the mesh and the autolevelling, with the same glass and the same manual leveling, i'm able to print properly. So, there is something strange with the UBL or with the auto bed levelling, because enabling it make more issues than without.

Any idea ? I've tried 2 different bltouch (both genuine) on 2 different printers, same behaviour, the nozzle is lifted and lowered with no apparent reason and for too much distance (even 1-2mm)

A glass can't have a 1mm "hole" in a couple of centimeters, it's physically impossible and that would be visible by eyes.

Bob-the-Kuhn commented 5 years ago

If you have a system that works well then stick with it.

If it has problems then take a look at the following. I prefer the UBL system myself.

UBL

Mesh leveling

guestisp commented 5 years ago

The working system is the manual bed levelling, that doesnt produce good first layers, obviously, as it doesnt level in the center but only in the corners

Already saw these guide, they are what i've followed to enable the UBL

reloxx13 commented 5 years ago

upload configuration.h and configuration_adv.h which marlin version u use? post ur startcode. describe ur leveling procedure.

and fix the title of this issue.

guestisp commented 5 years ago

upload configuration.h and configuration_adv.h

As soon as I go to office, give me 30 minutes or less

which marlin version u use?

bugfix-2.0.x

post ur startcode.

M190 S60 ; set bed temperature and wait for it to be reached
M104 S205 ; set temperature
M412 S0;
G28 ; Home extruder
G29 L1 ; Load the mesh stored in slot 1 (from G29 S1)
G29 J   ; No size specified on the J option tells G29 to probe the specified 3 points and tilt the mesh according to what it finds.
; Filament gcode
M109 S205 ; set temperature and wait for it to be reached
G21 ; set units to millimeters
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
G92 E0
;LAYER:0
G1 Z0.300 F7800.000

describe ur leveling procedure.

z-offset set as 0 G28 Z is set to 10 I move Z axis down until touching the paper sheet Read the Z value from the info screen (ie: -2.3) Set z-offset to -2.3 Store settings G28 Z is set to 12.3 Move Z to 0 The nozzle touch the paper sheet as expected

and fix the title of this issue.

Sorry for the title, i didn't see that the title was wrote properly, I was on mobile. Fixed

guestisp commented 5 years ago

I've checked the config files and I'm using the one provided with Marlin, for Geeetech A20M except enabling the BLTouch and setting the probe offset. No other differences as I'm trying to fix the bed levelling, everything else will be addresses after all

#define BLTOUCH
#if ENABLED(BLTOUCH)
  //#define BLTOUCH_DELAY 375   // (ms) Enable and increase if needed
  #define Z_MIN_PROBE_REPEATABILITY_TEST
  /**
   * BLTouch V3.0 and newer smart series
   * For genuine BLTouch 3.0 sensors. Clones may be confused by 3.0 command angles. YMMV.
   * If the pin trigger is not detected, first try swapping the black and white wires then toggle this.
   */
  //#define BLTOUCH_V3
  #if ENABLED(BLTOUCH_V3)
    //#define BLTOUCH_FORCE_5V_MODE
    //#define BLTOUCH_FORCE_OPEN_DRAIN_MODE
  #endif
#endif

#define X_PROBE_OFFSET_FROM_EXTRUDER -20    // X offset: -left  +right  [of the nozzle]
#define Y_PROBE_OFFSET_FROM_EXTRUDER  -15   // Y offset: -front +behind [the nozzle]
#define Z_PROBE_OFFSET_FROM_EXTRUDER  0  // Z offset: -below +above  [the nozzle]
Bob-the-Kuhn commented 5 years ago

When I enabled UBL my first matix was terrible. I did the G29 P1 to get the initial matrix but after that I kept repeating the "G26 , G29 P4" loop until I was getting good first layer adhesion everywhere.. After that I used G29 P6 to shift everything up/down based on test prints.

guestisp commented 5 years ago

I can try What seems strange to me is that even by setting a z-offset much lower than needed, in example -3.50 when the proper one is -2.50, the nozzle is still too high

Is zoffset ignored when using the ubl mesh? I have to rebuild the mesh every time i change the Z offset?

guestisp commented 5 years ago

Side question: with UBL enabled, can I temporary disable the mesh and just use a plain simple 3Point level or a LINEAR leveling with 4 or more points, without the mesh correction ?

Roxy-3D commented 5 years ago

I can try What seems strange to me is that even by setting a z-offset much lower than needed, in example -3.50 when the proper one is -2.50, the nozzle is still too high

Is zoffset ignored when using the ubl mesh? I have to rebuild the mesh every time i change the Z offset?

Usually... This behavior is because a person is changing the Z-Offset in the firmware (configuration.h) and not in the EEPROM. Are you doing a M502 & M500 after changing the firmware?

Side question: with UBL enabled, can I temporary disable the mesh and just use a plain simple 3Point level or a LINEAR leveling with 4 or more points, without the mesh correction ?

Yes. You can do a G29 P0 to zero the mesh. And then a G29 J to do a 3-point leveling. You can do a G29 J 2 for a 2 x 2 grid of probe points.

guestisp commented 5 years ago

Usually... This behavior is because a person is changing the Z-Offset in the firmware (configuration.h) and not in the EEPROM. Are you doing a M502 & M500 after changing the firmware?

Yes. But when I'm talking about changing the z-offset, i'm referring to changing it from the LCD and the save (still from LCD)

Yes. You can do a G29 P0 to zero the mesh. And then a G29 J to do a 3-point leveling. You can do a G29 J 2 for a 2 x 2 grid of probe points.

Thank you. This should disable the mesh and activate the 3Point or the Linear. What if I would like to try the BILINER? Just add a number of points greated than 2 to "G29 J" will enable BILINEAR or still LINEAR with multiple points ?

Zero-ing the mesh is mandatory ? Isn't possible to temporary disable it for a single print ?

Vertabreak commented 5 years ago

if you did not remove the original z end stop you will get false triggers from it as the probe and the end stop run on the same z min pin, if the original z end stop is removed it will allow the probe to function without being false triggered and blocked by the original z end stop. this is the only thing i can think of that would result in what you describe and has also been documented in another post here on GitHub. G29 J is used to tilt a existing mesh, zeroing the mesh would result in a flat tilted plane with UBL to use bi-linear you have to disable UBL and enable bi linear and re-flash there totally different solutions to bed leveling.

guestisp commented 5 years ago

I don't have the endstop.

Currently, I'm able to print a decent first layer, just trying to figure out the source of some strangeness. In example, does make sense, with chinese printers, to have z-offset with 2 decimal? The printer is able to move Z to 0.10 and 0.15 differently ? Asking this because from the motion menu I can move just up to 1 decimal place, but the z-offset has 2 decimal places.

Vertabreak commented 5 years ago

the lcd menu motion moves are limited if you where to issue the gcode move command manually from a terminal you could type in a more exact number. as users above noted i also prefer UBL over the other bed leveling options works perfectly on all 5 of my printers.

guestisp commented 5 years ago

Sure, but does it make sense to adjust zoffset at 2 decimal place precision ? I don't think any FDM printer would be able to reach a 10 micron resolution on Z. Maybe i'm wrong

Vertabreak commented 5 years ago

i have never used more then 1 decimal place setting my z offset personally but others claim they must. i have also used the .06 layer height option in cura with no issue it just takes forever to print.

guestisp commented 5 years ago

So, if you can print at .06, some printers are able to print at that resolution.

My correct z-offset is -2.40, if I set -2.40 first layer seems to be too hight, if I set -2.50 seems to be too low. It seems that Marlin is correcting too much. The paper sheet at -2.50 offset is totally fixed, doesn't move at all, this usually means a too low nozzle.

This is what I'm trying to figure out. Why setting a -2.40 offset (that is correct) Marlin doesn't stay too hight and with -2.50 is too low? The mesh seems correct

Vertabreak commented 5 years ago

the offset moves the entire mesh up or down if your trying to correct 1 spot on the bed the offset will not do that.

guestisp commented 5 years ago

Is not one spot. I have one spot a correct and one spot (a couple of centimeter on the right) too low. Adjusting the zoffset a little bit should solve, the correct post would be a little bit higher with not apparent drawback and the too-low spot will be corrected. But doesn't seem to work. Currently I get a good, but not perfect, first layer in the center of the bed.

I'll try to print near the edge, if i'm able to print properly even there, everything would be ok. Not perfect but still good is something acceptable for my prints. When I have more spare time i'll do a mesh edit point by point

I'll keep you updated in about 30 minutes

Bob-the-Kuhn commented 5 years ago

There's a better explanation of the G29 options/function in the file ubl_G29.cpp

I use G29 P4 to edit individual points in the mesh. That should help with your "point X is OK but point Y isn't" problem.

I have a glass bed so I just circle the problem area with a dry erase marker, use G29 P4 and make an adjustment when the nozzle is over the problem area.

One possible cause of the "point X is OK but point Y isn't" problem is too few points in the matrix. On my machine a 5x5 matrix is OK but I see others that use 7x7 or even 9x9.

guestisp commented 5 years ago

I have a 7 7 Matrix. I can try a 8 8 or 9 * 9 Isn't an issue for the available memory? I get some warnings during the compile

Vertabreak commented 5 years ago

Can use all but the last 1kb ram it won't compile with less warnings don't mean much. max ubl grid is 15x15 and takes hours to build a mesh. Can disable other features to make space.

guestisp commented 5 years ago

Build time is not an issue, i have to do this just one time . If the memory warning can be safely ignored, i could try with a 9 * 9 mesh. There will be 32 additional points

Vertabreak commented 5 years ago

I tested all the way up to 15x15 then scaled back till it wasn't accurate enough. I can get away with 3x3 on my bed if I wanted. my builds usually have 7x7 due to community demand. Could even print on a 2x2 it wasn't as accurate but was useable.

Bob-the-Kuhn commented 5 years ago

7x7 is probably OK.

Have you tried G29 P4?

guestisp commented 5 years ago

7x7 is probably OK.

Already using 7x7

Have you tried G29 P4?

Not yet.

guestisp commented 5 years ago

Could even print on a 2x2 it wasn't as accurate but was useable.

Well, yes, I'm able to print with a simple 3 points leveling, but as i have a sensor probe, i would like to get the first layer as accurate as possible.

Bob-the-Kuhn commented 5 years ago

G29 P1 with my BLTouch has never produced a useable matrix for me. Here's how I tune my matrix:

  1. Move the head over the print bed & Issue G29 A and the G29 P1
  2. Issue G29 S2 to save the matrix
  3. Move the head over the print bed & Issue G26 command to print out a test pattern,
  4. Using a dry erase marker, circle the problem areas
  5. Move the head near a problem area and the issue G29 P4 R10
  6. The head moves to the nearest point in the matrix. If that isn't a problem point then just press the knob (without turning it). The head will move to the next point in the matrix (it goes in a circle around the original point). Once you're at a problem point turn the knob. I usually do 0.050 or 0.025 changes.
  7. Repeat 5 and 6 until all problem areas have been adjusted
  8. Issue G29 Sx where x is a new slot or one you don't mind writing over.
  9. Clean off the print bed
  10. Repeat 3-9 until happy
  11. Try a real print
  12. If there's problems with the first layer issue G29 P6 Hxxx where xxx is the amount you want to move the head up or down.
  13. Issue G29 Sx where x is a new slot or one you don't mind writing over.
  14. Repeat 11-13 until happy
  15. Issue M500 to make the last saved matrix the default.

The reason why I put the head over the bed before issuing a command is my head can go beyond the bed and some settings of the matrix result in the head being too low and hitting the edge.

Bob-the-Kuhn commented 5 years ago

Rather than doing 12 & 13 you can use babystepping to adjust the head height during a real print.

For me babystepping doesn't work about half the time. Wonderful when it works.

Vertabreak commented 5 years ago

Calling it auto bed leveling is rather deceptive honestly. makes it sound like it will do it all perfect and that isn't the whole truth. I get 1 micron deviation on my probe running m48 it's still never perfect it good but I still have to fine tune it. Probe assisted leveling seems more appropriate a name.

Roxy-3D commented 5 years ago

What if I would like to try the BILINER? Just add a number of points greated than 2 to "G29 J" will enable BILINEAR or still LINEAR with multiple points ?

If you want to use Bi-Linear... You need to change your Configuration.h file to turn it on and rebuild the firmware. There are slight differences in how the Z-Height correction is calculated within a mesh cell. But you would be hard pressed to actually see a difference in the print.

Vertabreak commented 5 years ago

It's possible to setup bilinear to save the mesh also but I have far greater control and success with ubl. Can't edit the mesh with bilinear only build new.

guestisp commented 5 years ago

Up to which level the UBL will correct the Z ? I'm at 8.5 in a test print (benchy) and i can see the Z axis moving up and down in the same level. Is the UBL that makes (or try to) the Z distance from the bed flat and consistent on the whole surface?

Bob-the-Kuhn commented 5 years ago

Yes, UBL is what moves the head up & down to keep the head the same height from the surface.

There's an ENABLE_LEVELING_FADE_HEIGHT option that will gradually eliminate the compensation being done by UBL. That's the way most people run. I don't know if it's on by default.

guestisp commented 5 years ago

I've checked. Fade height is disabled here, so why z axis was moving up and down ?

Bob-the-Kuhn commented 5 years ago

If you enable it then that'll gradually eliminate the compensation. I think 10mm is the usual setting at which the compensation is totally gone.

guestisp commented 5 years ago

It's set to off.

Roxy-3D commented 5 years ago

It's possible to setup bilinear to save the mesh also but I have far greater control and success with ubl. Can't edit the mesh with bilinear only build new.

It is possible to edit the Bi-Linear mesh's. But you need to do it via the M421 command. We really should make the interactive mesh editing available (as an option) for Bi-Linear also. It would not be that difficult to extract the interactive mesh editing code and allow it to be compiled in for either bed leveling system.

Roxy-3D commented 5 years ago

Can't edit the mesh with bilinear only build new.

This is not true. It is true you can't do the interactive mesh editing that UBL has. But you can display your Bi-Linear mesh and then use M421 to move those mesh points up or down.

guestisp commented 5 years ago

I've doubled checked and my fade height is disabled but I can still see the Z axis going up and down, even at layer 150 (about 30mm). How can I totally disable this compensation ? I would like to try the compensation just on the first layer.

AnHardt commented 5 years ago

If you disable fade height - Marlin will not fade out the correction, but will always apply the full amount. Better set fade_height to about 1 to 3 layers height. When the first layer is fully compensated but the second if fully not compensated, you will likely see a adhesion problem between the first and second layer - about the same magnitude you'd have between bed and first layer when bed-leveling is off

guestisp commented 5 years ago

Ok, so is normal that at layer 150-170 marlin still try to compensate the bed level.... It does to keep the height uniform across the whole print, right ?

spilz87 commented 5 years ago

Did you solve your original issue ? I have the same (if I understand well) : If I do a homing G28 my nozzle is just on the bed, but after a G29 the nozzle is no more on the bed. I find a way to solved it by comment this line : https://github.com/MarlinFirmware/Marlin/blob/bugfix-2.0.x/Marlin/src/gcode/bedlevel/abl/G29.cpp#L959

Let us know

guestisp commented 5 years ago

I've changed many config in these days (including moving from UBL to a simple 3points) but i don't think the original issue is solved

boelle commented 5 years ago

@guestisp could you change the title from [question] to [BUG]?

guestisp commented 5 years ago

Sure but i'm not really sure it's a bug or not

boelle commented 5 years ago

put configuration.h and configuration_adv.h in a zip file and attach here but make sure the hardware side of your printer is solid

to me it sounds strange that you get different results

guestisp commented 5 years ago

Attached the Configuration.h The _adv is almost untouched from the stock one and as far as I know, there isn't anything related to the bed levelling

Configuration.h.txt

guestisp commented 5 years ago

What I know for sure (but I don't know why) is that any ABL without mesh, in example the 3POINTS and LINEAR, does the G29 properly, but during the print, it doesn't correct.

If I enable a mesh-based levelling, without any additional changes to the configuration, the correction is done properly

guestisp commented 5 years ago

Ok, so, let's see if this is a bug or not.

With a 3POINTS or LINEAR bed levelling, during a print, the firmware is supposed to correct the levelling, right ? Thus moving the Z axis up and down like with any mesh-based levelling.

Is this correct ? Because i've tried in almost every possible way, with 3POINTS or LINEAR levelling, there is no correction at all. If I change to any mesh-based levelling, a correction is made properly.

boelle commented 5 years ago

i use bi-linear with 3 probes on each axis, this is the best i can do for the mk42 bed on my mendel90 printer

with that i have correction too

i think we can think of 3 point as a tilt correction only, ie the printer assumes that the bed is totally flat but tilted, so if the bed is bent you will have an issue

not sure how linear work

but with mesh you have more probe points and hence the printer can correct more