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Serious Bed Homing Problem

Discussion in 'Troubleshooting' started by adikted2astro, Jun 25, 2019.

  1. tiagomaricate

    tiagomaricate Member

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    hahahah no problem!

    I was just recording a video showing to a friend this issue with the sensor.
    R2 has a mechanic sensor under the chassis where a stick from the bed enters and stops the Z-axis.
    But to stop Z-axis elevation, there is only that sensor under the hotend. Looks an optical sensor.
    This optical sensor doesn't work with some material.
    Check the video:

     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I concur -- the sensor is (I think) a UV LASER LED and it seems to work better with darker surfaces.
     
  3. tiagomaricate

    tiagomaricate Member

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    I think is related to the reflectivity of the material.
    Most of the time, brighter materials worked better.
    But I'm doing more research... exploring the possibilities to understand better how the printer works.
     
  4. tkoco

    tkoco - -.- --- -.-. ---
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    2 things come to mind after watching the posted video:

    1) The Buildtak surface on the print bed is in terrible shape. Fingerprints, dust and/or left-over filament debris can throw off the IR sensor reading. The video already demonstrates that the IR sensor is working.

    2) Changing the measuring surface by blocking the IR sensor from reading the print bed is a recipe for disaster. The very first measurement is to calibrate the switch-off electrical point in the Z Axis. If you subvert that measurement as demonstrated in the video, then no measurements afterwards are guaranteed.

    Suggestions:

    1) Change out the Buildtak surface for a fresh one before attempting the Fine Tune Z Offset.

    2) Clean the print bed with 91% isopropyl alcohol before starting any calibrations.

    3) Double check the print bed level.
     
  5. tiagomaricate

    tiagomaricate Member

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    Actually I discovered this issue when the print bed was new.
    The sensor didnt work. So I used sandpaper to "destroy" the surface and, sometimes, the sensor started to work.
    But with the print bed as new, no way to the sensors work.
     
  6. adikted2astro

    adikted2astro Active Member

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    I already know what your problem is after watching only half of the video. You are trying to home and/or use the IR sensor with the extruder all the way to the front of the bed. That right there is your problem. If you want to make sure the IR sensor works properly, you should never try to use it on any of the edges of the bed. If you home your machine, do so in the middle of the bed, or somewhere near it. The IR [sensor does not work very well on the edges. I never use mine for anything within 25mm of each edge. Use this forum and search for UBL bed leveling, or even MESH bed leveling. Do either of these methods and you won't have any problems. You can change the auto bed leveling points too if you want. You just need to modify the code.

    Also, @tkoco is correct, your bed looks horrible. Replace that BuildTak sheet with a new one, clean it with alcohol, home your bed near the center of the bed, and you should be fine. The fact that your bed is so messed up basically guarantees your IR sensor won't work. I know you seem to think a new surface is worse, but I assure you it is not. Also, placing a crumpled sheet of paper under the sensor will also give you problems because it's not flat and there's no way to always place it in the exact same spot for homing/leveling. One thing I found out through a lot of hard work, blood, sweat, and tears is when you home your bed, or perform bed leveling, you should do so on a COLD bed, not a hot one; the colder the better. I found that the IR sensors work best on a cold bed for some reason. You would think that the opposite is true but it isn't. I spent a long time testing and proving that statement.

    I would suggest ditching the Fine Tune Z Offset feature for UBL bed leveling, it's much easier and will stay level for dozens of prints before needing to tune it again. It might be a PITA at first, but once you get the hang of it, it's easy. I would also suggest using a garolite build surface instead of buildtak, but that is just my personal preference. This forum has a wealth of information and is an excellent resource for Robo owners. Use it, peruse it, and even abuse it if you have to :)
     
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  7. tiagomaricate

    tiagomaricate Member

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    Thanks, matte!
    The leveling by corners/middle point is automatic from the printer.
    Not sure if is possible to change it or where to change it.
    I'm doing an overall dismount/cleaning to be sure there is no dirt on the parts.
    Also, I'm testing several materials using the sensor to check if is related to the color or surface.
     
  8. adikted2astro

    adikted2astro Active Member

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    You can change pretty much any setting by modifying the Arduino code and reflashing the printer. If you have never done that before I would advise you to start asap because it's relatively easy to do and you have much greater control over your printer and how it behaves. I never liked the auto bed leveling from Robo; I think it's extremely inferior to UBL or MESH and I always had problems with it. To get started on modifying the code, see the UBL bed leveling thread here in the forum (or MESH leveling). I believe the instructions are there to get you started. Once you have downloaded the Arduino IDE and open the code in your sketch folder, look at the configuration.h file (tab). That's pretty much the only part of the code you will modify (there are a LOT of tabs in the sketch folder). Open that up and slowly go through it, looking at each line of code and what it does. It will take time, but it's worth it in the end, I assure you. Once you have understood what is going on, you can change any aspect of your printer's operation: min/max temps, homing location, auto bed leveling points, bed size, etc.

    HERE is the UBL thread: http://community.robo3d.com/index.php?threads/marlin-for-the-r2-ubl-enabled.19405/
     
  9. tkoco

    tkoco - -.- --- -.-. ---
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    The only cautionary note here is that using any other firmware besides the official Robo version will most likely break the wizards ( as pointed out earlier in this thread )
     
  10. tiagomaricate

    tiagomaricate Member

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    Is there a way to rework the interface and wizards, maybe using a code sequence?
     
  11. tkoco

    tkoco - -.- --- -.-. ---
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    I am considering modifying the official version of firmware to enable the UBL leveling instead of the default and see if anything breaks.
     
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  12. tiagomaricate

    tiagomaricate Member

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    @adikted2astro @tkoco

    Did you manage to put UBL working by default with R2?
    Also, is it necessary to update merlin?
     
  13. tkoco

    tkoco - -.- --- -.-. ---
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    Works in progress. Not finished yet.
     
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