MBL titan dual homing nightmares

Discussion in 'Calibration, Help, and Troubleshooting' started by fpex, Jul 10, 2016.

  1. fpex

    fpex Well-Known Member

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    I am getting to the point that soon I will burn the BB instead of my rumba.
    I have spend the last two days with this silly machine and its homing problems.

    I have a BB with hybrid titan, pancake version, swapped z-axis/extruder motors and the clever3d bed.

    I run MBL and all is fine. Homing after MBL is fine.
    When I start a print, the homing at the beginning of the print goes too low always. This results aways in a failed first layer and therefore I am unable to print.

    What is wrong here? I never experienced this before. I start to feel hate for this auto-MBL IR sensor stuff

    Thanks.
     
  2. Dr Jeep

    Dr Jeep Well-Known Member

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    I don't have your configuration (Pro rather than Dual, KS extruder rather than titan, standard BB bed) but in 200 hours of printing (about 50 print jobs) I have never had a problem with homing or levelling (I use the ABL sometimes but my bed is level to start with)

    Either one of your customisations is causing a problem or you need to contact E3D support I think given the frustration you are having...maybe you have a bad IR sensor or maybe it just isn't happy with the bed you are using. Is there evidence online of someone using the IR sensor with that bed, how did it work before you changed the bed ? The designer of that sensor has already stated it doesn't work with plain aluminium beds or mirror beds but there is a tweak you can do to make it less sensitive to reflectivity.

    If you do repeatability tests by setting a IR distance above Z0 and then homing Z and using move axis to measure the distance until tip contact then what happens, if that drifts then either you have a bad IR sensor or a incompatible bed.
     
  3. fpex

    fpex Well-Known Member

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    What is weird is that after MBL the bed homes perfectly. When the print starts (gcode from S3D) is goes 1mm too low. There have been times it went perfectly without an hitch, but lately I managed two prints on almost 20!
    The Z offset also has no effect whatsoever.

    It is like the Gcode somehow messes the Z homing

    I use an hybrid dual titan with Clever3d bed (the ALU with PEI one many are using)
     
  4. fpex

    fpex Well-Known Member

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    I changes my z offset and see if this stays stable, but I am really annoyed that the changes so much from print to print
     
  5. tohara

    tohara Well-Known Member

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    Does the MBL get deactivated when this happens? (Is the Z-axis correcting when it is moving in x or y direction?)

    What is your start script?

    Have you tried removing the homing from the start script and home manually before starting a print?
     
  6. fpex

    fpex Well-Known Member

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    I ma not sur MBL works at all yo be honest.
    MY start script is pretty standard:

    ;BigBox Hybrid-Dual Start Script Begin
    ;relies on M83 (use relative extrusion distances)

    ;home
    G28

    M117 Preparing
    M190 S50 ; wait for bed to reach 50C
    M140 S[bed0_temperature] ; set bed temperature
    M104 S[extruder0_temperature] T1; set extruder temperature

    ;set values
    ;M92 E417.5 ; adjust steps per mm for your filament
    M218 T1 X38 Y0 ; set extruder 1 offset

    ; lift the head
    G91 ; relative positioning
    G1 Z5 F250 ; move Z axis by 5mm
    G90 ; absolute positioning

    ;move to dock
    T0 ; select extruder 0
    G1 X70 Y200 F3000 ; move to position in front of dock
    G1 X70 Y235 F3000 ; move into dock

    ;heat bed
    M190 S[bed0_temperature] ; wait for bed temperature

    ;heat extruder 1
    T1 ; select extruder 1
    M109 S[extruder1_temperature] ; set extruder 1 temperature and wait

    ;prime extruder
    T1 ; select extruder 1
    G1 E15 F200 ; reverse end of print retraction
    G1 E10 F50 ; extrude 10mm

    ;move out of dock
    T0 ; select extruder 0
    G1 X80 Y235 F3000 ; move a little in dock
    G1 X80 Y200 F3000 ; move out of dock

    M117 Print starting

    ;BigBox Hybrid-Dual Start Script End

    my config is here: https://www.dropbox.com/s/zqx3fnp073g8zxr/Configuration.h?dl=0
     
  7. tohara

    tohara Well-Known Member

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    One thing I have seen that can create problems is if you home before the nozzle is heated. If there is a blob under the nozzle the bed will hit it after the homing and skip steps on the z-stepper resulting bed beeing too low.
     
  8. fpex

    fpex Well-Known Member

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    I saw it happening. I am starting to think I need accepting the reality that I need to change z offset more than once.
    MBL works, just checked.
     
  9. Old_Tafr

    Old_Tafr Well-Known Member

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    Isn't there also a mod from Greg to mount the IR sensor at the right hand side of the bed triggered by the bed or the frame? so eliminating the problems with bed type.

    Found it...

    https://forum.e3d-online.com/index.php?threads/gregs-bed-ir-sensor-mount.1416/
     
    #9 Old_Tafr, Jul 10, 2016
    Last edited: Jul 10, 2016
  10. Alex9779

    Alex9779 Moderator
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    @fpex this is my profile it seems and I print very successful with it.
    How do you level? With a paper strip?
     
  11. fpex

    fpex Well-Known Member

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    I level with a paper strip and I think the problem is somewhere in the MBL doing a good bel levelling but the distance from the nozzle somewhat changes because the IR gets different lighting at times. I probably have no choice but do a homing and change offset (if needed) before any print.

    I believe that a better solution is to move the sensor or use an end stop on the side of the bed.

    @Alex9779 yes I took your S3D config and I am changing them but not the scripts.
     
  12. Alex9779

    Alex9779 Moderator
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    You could try a strip of tape where the IR is placed when homing... Though I have don't have such issue with homing... I can't believe the blue plate behaves different than the natural which I got and I don't have problems with incosisten homing...
     
  13. fpex

    fpex Well-Known Member

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    The only other explanation is that somehow the IR mount has changed position due to vibration. Something very difficult to verify.
     
  14. Alex9779

    Alex9779 Moderator
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    Can reproduce the inconsistency when you home multiple times? Move the head by hand several times then home again... Move the bed up and down and home...
     
  15. mike01hu

    mike01hu Well-Known Member

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    I had trouble with level due to the X and Y carriage screws becoming loose, so I suggest you tighten all the rod clamps and mounting screws. I have the red PEI coated bed and it homes about 2mm further away from the bed but it does not seem to have any serious effect on levelling. What I do find is that changes in ambient temperature make a slight difference and I always check the initial home position after restoring memory if the ambient temperature is largely different to the previous time of use.
     
  16. fpex

    fpex Well-Known Member

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    All is tight, I think my issue is related the working conditions affecting the bed as well as the IR.
    Maybe if the IR would be on the side of the bed triggered by the frame it might be better.
     
  17. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

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    Different colour pigments might reflect IR light different. So maybe the blue pigment used here is no good for IR.

    The suggested tape bit here should reveal if this is the case.
     
  18. fpex

    fpex Well-Known Member

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    I have no solution for this problem and it is so frustrating because the printer is useless.
    I tried again to leve the bed (MBL with paper).
    Either the homing after MBL is bad (too high) or good.
    If it is bad and aI start a print, homing at the beginning of the print brings the bed too high anyhow.

    If the homing after MBL is too high and I correct it with the z offset, then if I home several time the bed move down at z=0 increasing the durance and eventually getting at a stable position.

    I also notice the MBL keeps getting the front of my bed higher than the back.

    I am getting really frustrated as now I manage one print out of 10 or more trials.

    I also tried putting a paper and tape under the IR when homing, no difference.
     
  19. Alex9779

    Alex9779 Moderator
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    @fpex did you have the same problems with the glass plate?
     
  20. fpex

    fpex Well-Known Member

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    Cannot compare because since then a lot has changed. But I can put one now one and try.
    I have now tried the following:

    1) home, disable steppers, move head around and home
    2) home, move bed down home,

    In 1 z offset seems to make no effect and Z is always the same. if I print bed homes at print start too high
    in 2 the bed homes too low. In print Z home higher.

    I start to think maybe my z steps are not right? But I did measure and calibrate with a calliper.
    Maybe I should disable MBL as well as see what happens. The X bars flex a little bit but it is acceptable
     
    #20 fpex, Jul 12, 2016
    Last edited: Jul 12, 2016

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