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Partial Answer R1+ PEI Sheet?

Discussion in 'General Questions' started by Eric Viglotti, Jan 4, 2018.

  1. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    In the past this has been discussed many time. the build area and the heater do not cover the same amount of space. the heater only covers about 67% of the build area. Glass is an insulator not a conductor of heat, so you WILL get uneven heating where the heater is NOT located.
     
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  2. Eric Viglotti

    Eric Viglotti Member

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    Sadly this could be a bit challenging because if you look at the attached, this is the underside of the new bed they shipped me after I destroyed the glass on the first one and now you can see they have this big piece of foam holding everything down and I can't really "feel" for where the heater area starts or stops. So this may be a dry hole, I'm not sure :(
     

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  3. Geof

    Geof Volunteer Moderator
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    You'll find about the center if you feel the wires. Where they stop will be about the center (the 2 wire is the thermistor).
     
  4. Eric Viglotti

    Eric Viglotti Member

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    I'll check that out. How far then is the front and back of the heater area from the center?
     
  5. Geof

    Geof Volunteer Moderator
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    cant recall the exact size of the heater, but you should be able to feel the heater inside that pad. the element is pretty darn close to the outside of it.
     
  6. Avrution

    Avrution Member

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    You aren't alone - mine is exactly the same way as what you describe (temps) and I also have lifting issues like you showed. It doesn't happen every time though. I have noticed that even with the lifting I have great adhesion.

    I watch my time lapses and see how the lifting doesn't start until pretty far into the printing process. Have you watched the printing process to see when it actually starts?

    My PEI sheet arrived today and I was hoping it would resolve the same types of issues you still have.
     
  7. KTMDirtFace

    KTMDirtFace Well-Known Member

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    So I don't know why the back of the bed would be having issues. I consistently had issues on the right side? ( or left ..can't remember ) due to the auto leveling. I dont have the left right problems anymore after changing to jims IR sensor.

    I noticed that if I printed with a raft, the first layer raft was always stuck down...so now this is what I do with no bed heater.

    Its actually way excessive, and extruding way to much on my first layer..but it works and it helps..so I run with it.

    My simplify3d settings.. Probably kind of a hack, but it works really well for me.

    This combined with a 0 offset layer skirt of 5-10 loops for long skinny parts..and I don't have anything curling up.

    By the way I have not had a heated bed for about a year. I use an aluminum bed, with sanded lexan clipped on top of it. I think i have to do this "hack" because i dont have a very flat surface...but it works.
    [​IMG]
     
    #27 KTMDirtFace, Jan 10, 2018
    Last edited: Jan 10, 2018
  8. KTMDirtFace

    KTMDirtFace Well-Known Member

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    This was printed with no bed heater, and I think 10mm skirt at 0 offset..with my crazy 150% first layer height.
    No curling at all. I did have to clean up the skirt afterwords but it works

    [​IMG]
     
  9. Eric Viglotti

    Eric Viglotti Member

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    All great comments, thanks everyone. I looked again and was able to feel where the heater is and it actually is dead center on the drawing on the bed that indicates the "hot" area. Though interestingly the range of the whole bed goes well past this printed square in the back and the Cura profile that was given to me by Robo support states that the maximum depth is 245 mm, but yet the printed square on the bed, which matches the heater, is only 220 mm. So maybe even though Cura thinks my bed area is 245 and even though the bed can slide forward and backward to cover the entire 250 mm of the PEI sheet front to back, perhaps I need to consider the print area to be closer to 220 to match the heater and not the full 245/250? This all seems so weird.

    And as for Avrution's question, it seems to start pretty early on with this example print, but I could swear I have other longer jobs where I watch it for 10 hours and it's fine and then randomly after that it starts lifting, but I may be wrong there as maybe that's not possible...
     
  10. KTMDirtFace

    KTMDirtFace Well-Known Member

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    The bed probe has never lined up with the graphics in my experience. I wouldn't worry about that.
     
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  11. Geof

    Geof Volunteer Moderator
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    graphics are literally just decoration :D they will never be right unless something is wrong with your machine ;).

    The only time front to back is an issue that I've seen is either autolevel is messing up (may need to relevel x to y) or tram the ya xis where its as flat as possible. Or! You may have something cracked/broken. I'd inspect the y bearing blocks (pillow blocks) for cracks or damage. If you wiggled the bed side to side do you feel more movement on the back of the bed?
     
  12. Eric Viglotti

    Eric Viglotti Member

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    FYI, per an idea KTMDirtFace about previously having this problem more left to right, I decided to change from one slip of paper between the back magnets to a folded slip of paper between the back magnets to try to level up the bed from front to back. The print ran successfully this time, so I'll continue from here and hope for the best!
     
  13. Avrution

    Avrution Member

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    I don't think you are wrong. I had a 7 hour print and everything started great for the first hour or two and then all the corners magically lifted up like they were hit with a blow torch. Sometimes I just raft and everything is perfect.
     
  14. Eric Viglotti

    Eric Viglotti Member

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    Thanks Avrution, good to know. My challenge is some jobs have to have a flat, smooth bottom so I don't have the option of a raft but that's a good reminder as I need to start doing that for all the jobs where it doesn't matter, just makes it more likely to succeed.
     
  15. Geof

    Geof Volunteer Moderator
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    Either your Z offset isn't correct or you have adhesion problems if your raft is fixing the issue. the PEI can be scuffed up with the rough side of a kitchen sponge or even sanded (will look dull) to promote adhesion. Make sure its clean. Also make sure your bed temp isn't so high that its causing the part to warp.
     
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