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Bring The Heat!

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  • Bring The Heat!

    I've mentioned in a couple of posts that I'm working my way through https://teachingtechyt.github.io/calibration.html. The Slicer Flow Calibration section involves printing a single wall hollow cube that I'm sure many of you have seen/printed.

    I had been printing PETG at 235C for the hotend & 70C for the bed. While printing the 1st cube I noticed the bottom corners were lifting off the bed: i.e. they were warping. I tried lowering the bed temp to 60C. I didn't need to even let the print finish to see it wasn't working. So, I started a new print with the bed at 80C. That made the difference:

    Click image for larger version

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    If you look at the larger version, you can see that there is still a tiny bit of warping. I decided to raise the normal bed temperature to 85C. There is also a small amount of elephant's foot, which I'm hoping the rest of the sections at the Teaching Tech site will help me eliminate. I am wondering if reducing the 1st layer flow a bit will help. Or, maybe, changing the Z Offset a bit, although I'm hesitant to do that.

    Both prints were done using Magigoo on a glass bed.

  • #2
    I can only speak for ABS, which is a champion in bending and failing.

    The the higher the temperature, the better. Also make a good contact with the bed, but no too much. If you have to much contact, the material gets squished to the sides (with no real contact to the bed) and less material will be placed on the actual line (more or less no contact to the bed). As the squished out parallel lines have next to no real layer adhesion and are hardened when the hotend tries do place the actual material to the same spot it gets ugly. It there for reduced the layer adhesion of the entire part.

    To reduce the elephant food you can use a slicer option "horizontal expansion of the first layer" in Cura. This creates a dimensional smaller first layer, so when it expands, the size is perfect.

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    • #3
      Originally posted by Geit View Post
      To reduce the elephant food you can use a slicer option "horizontal expansion of the first layer" in Cura. This creates a dimensional smaller first layer, so when it expands, the size is perfect.
      Thanks for that. I was going to try lowering the flow rate for the 1st layer, but now I'll search for horizontal expansion.

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      • #4
        I have been printing PETG at 250 and 85 with good results. Geit, what do you use for ABS? I have had variable results, especially on larger prints lifting off the bed. I tried 240 to 250 for nozzle and 95-100 for bed. with NO part cooling.

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        • #5
          I've been having some issues with PETG blobbing @ 235C/85C so, today, I lowered the hotend to 230C. The 1st print does look better.

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