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Inadvertent cause of poor auto leveling performance - Maybe?

Discussion in 'Off Topic' started by WheresWaldo, Oct 1, 2016.

  1. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    While editing new files for Marlin 1.1.0-RCBugFix I came across new settings for auto bed leveling recently added. It appears now to have at least three ways to determine level rather than the previous two. Marlin 1.0.0, upon which all Robo firmwares variants are based (I will not call them versions since they all start with Marlin 1.0.0), can auto-level using 3 arbitrary points on the bed or using a grid.

    The 3 point auto-leveling is pretty simplistic, it is fast but it depends on the bed being nearly 100% flat in order to work well. Similar in a way in which one would level a transit or camera on a tripod.

    The grid auto-leveling, which is enabled by default in Robo firmware is a bit more sophisticated and creates a grid of offsets to determine bed leveling, but because of its linear nature it really only levels in one plane. That is perfect if you bed is only tilted but not warped in any way. Hence the reason all of us that have struggled with auto-leveling have insisted that your bed needs to be fairly level in the first place in order for auto-leveling to work properly.

    The new auto-leveling method introduced sometime in September 2016 is a grid with a bilinear grid. I am not here to discuss the math involved since it is way over my head, suffice it to say that it creates a grid similar to the old grid auto-leveling except it works with beds that are less than flat and may be tilted in multiple directions, essentially a warped bed.

    Since Robo uses the linear method as well as having the weight of the entire hotend pushing down on the bed before the Z-Axis endstops trigger as well as bed flexing at different rates depending on where you probe, I believe that this is one of the major causes of poor leveling performance.

    Bottom line, if you want to stay with Robo supplied firmware, make sure you manually level your bed to the absolute best of your ability. If you move to a firmware based on 1.1.0 then make sure that bilinear is the method enabled and make sure you bed is moderately level, or switch to MESH as both are very close to the same thing (simplified explanation).
     
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  2. KTMDirtFace

    KTMDirtFace Well-Known Member

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    I plan to switching to Jims IR and Mesh soon.

    I dont think the bed flex is the problem at least for me. The problem for me seems to be that the right side weighs a ton more(due to motor) than the left and twist/skews the whole thing when probing the left. I imagine just switching to the IR sensor will make it much better.

    On both my robo3d no matter what trickery i do the left side of the bed always prints worse than the right ( right side smashed left is not. ).. Because of that if its a small enough print i print on the right side of the bed a lot .
     
    #2 KTMDirtFace, Oct 1, 2016
    Last edited: Oct 1, 2016
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  3. Rigmarol

    Rigmarol Well-Known Member

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    I have the opposite, my left side smashes with just ABL.
    I usually just start my print watch how the print begins then pause the print twist the left a little in the appropriate directions and I'm good to go.
     
  4. Geof

    Geof Volunteer Moderator
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    Dont have this issue or at least not enough to impact my print quality standards
     
  5. danzca6

    danzca6 Well-Known Member

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    Really? That shouldn't be needed. That's the opposite of auto bed leveling. Guys with betas would do that. So that is so 2014 :)
     
  6. Rigmarol

    Rigmarol Well-Known Member

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    LOL, I'll probably figure out how to fix it one day. It takes me less than 5 seconds and Im good until I turn the printer off.
     
  7. KTMDirtFace

    KTMDirtFace Well-Known Member

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    That is strange. The way I have got mine to work the best, is to G28 it. slide the head to the far left..then jog controls so the nozzle touches the bed and hold/turn rods so both switches trigger at the same time relative to the left side. This makes it skewed but its the only way on both machines i have got it to print with a somewhat even first layer on both machines.
     
    #7 KTMDirtFace, Oct 1, 2016
    Last edited: Oct 1, 2016
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  8. Ed Ferguson

    Ed Ferguson Active Member

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    I've seen slow motion video of the Robo leveling. The bed and rail flexing is so severe I'm surprised anyone can get it to work at all. An IR probe is the only way to go. Hopefully someone will sell an IR probe retrofit kit.
     
  9. danzca6

    danzca6 Well-Known Member

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    Kind of already here. You can get the IR height sensor and put it on the R1 and R1+... Got one... Love it
     
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  10. Ed Ferguson

    Ed Ferguson Active Member

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    Can you give a brief overview? Did it involve building a circuit board?
     
  11. danzca6

    danzca6 Well-Known Member

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  12. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Contact (PM) @jim3Dbot if you are interested in the IR sensor approach.
     
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  13. Ed Ferguson

    Ed Ferguson Active Member

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    Looks like a work in process - but very promising. Maybe someone will take up a collection from users and have some boards built. Or better yet, offer a kit. Curious to hear from others like yourself who get it working. Anything that removes one unreliable process from 3D printing is a good thing.
     
  14. danzca6

    danzca6 Well-Known Member

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    Not a work in progress... For sale and ready
     
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  15. danzca6

    danzca6 Well-Known Member

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  16. danzca6

    danzca6 Well-Known Member

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    The IR height sensor isn't a new thing with Robo. E3D BigBox uses it as well. David Crocker is the real father of the tech and Jim did a great job cloning it. I've got both and they work great.
     
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  17. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yea the thread is a bit old now, but is up-to-date (if long-ish).
    You can buy and use the sensor -- that thread has all the history and details.
     
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  18. Geof

    Geof Volunteer Moderator
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    Mechanical leveling with the pressing/flexing...no issues. Mechanically leveling and life is smooth :) at least as far as melting plastic goes haha.
     
  19. danzca6

    danzca6 Well-Known Member

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    Mr 1% haha!!! Just kidding buddy. Have you tried the IR? If not, maybe you just don't know how smooth life can get.
     
  20. Geof

    Geof Volunteer Moderator
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    No sir, mechanical all the way :). Click print and walk away. Any smoother it may run itself haha
     

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