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R2 PEI and Z-offset, I think

Discussion in 'Troubleshooting' started by Eric Viglotti, Jan 2, 2018.

  1. Eric Viglotti

    Eric Viglotti Member

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    I have had my R2 now for a few months after getting one of the first models and immediately I really beat up the PEI bed as I had no experience with PEI. Dave from Robo recommended that I get another PEI sheet from Amazon that I could laminate onto the existing R2 bed. I have been doing that for awhile with mixed results. I have gone through a few PEI sheets and most recently I ripped off what I had, but it left some uneven glue from the adhesive layer, but I went ahead and put another sheet on top of it with a new adhesive sheet. However, if you look at the attached screenshots, even after fiddling with the bed leveling wizard and fine tune z-offset, I can't get any consistency within the same part much less identical parts on different parts of the same bed. It looks from some screenshots that areas are too high of a z-offset (the little lines not creating a full first layer) but then when I printed a simple 180x180x1mm sheet, I had tons of rips and streaks which I believe is when the z-offset is too low.

    Any ideas on where to go next when everything is this uneven in all different spots on the bed that the bed leveling wizard likely wouldn't have a chance in helping?

    Thanks!
     

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  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Moved to R2 Forum
     
  3. Geof

    Geof Volunteer Moderator
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    I'd start by recommending (always) to get all the glue off the bed, you want the new sheet of PEI as flat as possible. Then you'll want to relevel the bed (in relationship with the nozzle). Once manually leveled the IR has much less work to do and can sometimes be more reliable or can be shut off (remove the G29 from the start up scripts).
     
  4. Eric Viglotti

    Eric Viglotti Member

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    Thanks so much. Two questions:

    1. What do you recommend to get all of the previous adhesive? Should I use Goo be Gone? I just don't know what might damage the bed or the heating elements as I definitely don't want to do that.

    2. The automatic bed leveling has always gotten me curious because it does it in four spots in the R1+ but about twice that many on the R2 and it takes much longer, and yet it didn't seem to help me here, but that may be because I just have too many dips and bumps than it can account for. That being said, I followed the steps in the https://robo3d.com/pages/cura-for-mac and cleared out all of the start and end gcode which means G29 is not in any of my gcode files exported from Cura. Does that mean that it is completely ignoring this minute or so of bed leveling or is the R2 just doing the G29 separate from what is in my gcode?

    Thanks!
     
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The R1+ should do 9 bed sample points :) if you are using the firmware bed leveling (G29 gcode) some slicers will do their own form of software bed leveling..

    Export one of your GCode files to disk a look. Could be that slicer is doing its own software leveling and not using the firmware G29 at all.
     
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  6. Geof

    Geof Volunteer Moderator
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    on the Prusa MK2 they recommend (and I followed their instructions) using Delimonine (its nasty) but have heard of other people using goo gone, their fingers and rubbing it off, a sharp razor scraper being very careful not to gouge the aluminum. whatever your comfortable with.
    http://manual.prusa3d.com/Guide/Replacing+the+PEI+sheet/133


    Ocotoprint will still have the G29 in its start up script (I know...why both...I'm not sure) so you'll need to pull up the octoprint menu on the web browser and remove there. Its basically the same leveling as the R1+ just with an IR instead of 2 mechanical switches. The R1 has 9 leveling spots no? Cant remember? Have been using Mesh for a long time ont he R1 machines I own.

    2nd option- @WheresWaldo has his firmware for UBL (I dont think mesh?) for his R2 posted on the forum. There are some changes int he start up behavior to his liking but I believe he is running without an issue.
     
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  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yes.
     
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  8. Eric Viglotti

    Eric Viglotti Member

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    All sounds good, thank you. I'll try some of the steps to remove the prior PEI sheet adhesive. As for the G29, I do now see that it is in the startup scripts in Octoprint, thank you for pointing that out.

    Thanks again everyone.
     
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  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yea, I forgot that :) Since we have OctoPrint in front of every printer now, I don't even use a startup GCode block in the slicers any longer and just defer that to OctoPrint.
     
  10. Geof

    Geof Volunteer Moderator
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    :eek: sacrilege
     
  11. Eric Viglotti

    Eric Viglotti Member

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    By the way, for those of you who have added your own PEI sheet to the R2 bed, did you try to take off the existing PEI sheet that is part of the R2's bed? Or is that even possible? I ask because Gizmodorks recommended that before putting on their PEI sheet that I remove any other things between it and the heating element, though I am not sure I really can do anything to alter the R2's bed correct? I think I have no choice but to have the R2 bed with it's PEI sheet, then the adhesive layer, than the Gizmodorks PEI sheet correct?

    Their point was that with too much stuff in the "sandwich" the bed wouldn't get hot enough (unless I turned up the heated bed temp from 60 to 70 degrees).

    Thanks!
     
  12. Geof

    Geof Volunteer Moderator
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    You have to get under the PEI and pull it off, then clean up the residue (glue) thats left over, clean the aluminum plate again then apply your new sheet.
     
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  13. Eric Viglotti

    Eric Viglotti Member

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    Thanks Geof, it's possible to do what you are saying with the actual factory R2 PEI sheet on their bed? I looked at it and it looked pretty sunken down and really integrated into the actual bed but maybe not?
     
  14. Geof

    Geof Volunteer Moderator
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    AFAIK yes. It has to come off to be replaced.
     
  15. Eric Viglotti

    Eric Viglotti Member

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    Thanks much.
     
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