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Watch Out For Gaps In Cura

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  • Watch Out For Gaps In Cura

    I've been trying to print this: https://www.thingiverse.com/search?q...&sort=relevant. One of the pieces in particular will not print properly if its brought into Cura and laid flat.

    It's the actual phone clamp that goes on the end of the arm. When imported into Cura it's standing up on end, which I think is nuts, so I laid it down flat by rotating 90 degrees. I was careful to ensure Snap Rotation was checked and that the rotation was exactly 90 degrees.

    Still, when I tried to print it, 1 half adhered to the bed just fine; the other didn't. I tried various temp & speed settings, but nothing worked. Then I remembered the issue I'd had printing the support arms for my Ender 5's printbed. So I checked and, sure enough, when viewed up really, really closely, I could see daylight between the bottom of the phone clamp and the printbed. Arrrrgh!!. Instead of trying to rotate the clamp so it fully contacts the bed, which I'm pretty sure isn't possible, because I don't think the model is completely flat, I instead sunk the model into the printbed by 0.2mm. I did this by using the move feature of Cura and changing the Z distance by -0.2mm. That worked.

    Now, the only issue remaining is the warping. This filaments.ca EcoTough filament seems to warp on really narrow parts, but it's such a unique filament I feel it's worth importing. Most likely, if I used a brim, it would be OK. The issue I have with that is Cura doesn't seem to offer the ability to use brims selectively on 1 model on the printbed, but not others. If someone knows how, please enlighten me.



  • #2
    Try to slice it into Prusa slicer....
    Thinking simple is the hardest way.....

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    • #3
      Make your own brim. Design a disk one layer thick an place copies along the perimeter where you have warping. A pretty nice trick I saw in someone’s YouTube.

      Cheers

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      • #4
        I saw that one Alan. It was the guy who prints a ton of ABS. He calls them mouse ears. I think his last name is Clough. I wasn't too worried about the warping; it printed OK anyway. I just wanted to point it out.

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        • #5
          Well, if the model is designed/exported in an angle of 88°, then for sure it won´t be flat when turning it 90°. It will fly or sink into the bed on one side.

          That is not the fault of Cura at all.

          Recent versions (at least V4 and up) of Cura allow to select a face you want to have as bottom and then it does a proper 88° rotation. You also can touch the ring (not the arrows) and turn the rotation wheel by hand. In that case you can just rotate in 1° steps and you need to know the angle you want to go for.

          So the select bottom function is the way to go, here.

          About the warping:

          To avoid warping there is a neat trick I use with 100% success. I use it when printing ABS, which lifts like crazy, but it works with every material that allows support.

          Usually a raft is used, but this take ages to print, the plastic waste is huge and when it bends there is most likely a print failure in progress as the nozzle will hit the massive object and layer shift or break of the rest of the raft.

          Instead go to cura settings and disable "automatic place object on build plate" or so. That way you can freely set the Z value when moving the object and it does not plop back onto the bed again. Select your model and the transform gadget on the left side panel (the top one). Enter 3mm into the "Z" field and you model is flying over the build place. Enable support and search for the brim options and select "brim under supports" and the "zik zak" support pattern. If you don´t need or want supports inside the model itself, turn on the support mode option to "over build plate"

          Now your model is 3mm in the air, supported by a full area brim and basic support to hold it up.

          If you print it, you just need to peel of the support at the bottom. Any lifting which hapend got compensated within the support and at the 3mm level you have a nice flat surface to print on. The support even prevents the model from lifting as - unlike a raft - the supports are tiny separated air pockets under the model, which keep temperature and act like a heater chamber.

          As said I use this technique for ABS all the time and hadn´t any failed print due to warping since then, as the warping happens always above the print bed, but below the model.

          3mm may sound a little high, but keep in mind the printer needs additional space to compensate the warping, so if the bottom lifts up 1.5mm it has additional 1.5mm to recover from that until it reaches the actual model. Since to the one wall zik zak pattern, the waste of material is minimal and the full surface brim keeps the model stick, even if parts where lifted do to the warping. Also those 3mm are just some single perimeter walls which are several millimetres apart, so compared to a raft this is only 1% plastic or so.

          I am sure this technique works for other materials, too.
          Last edited by Geit; 11-01-2020, 08:29 AM.

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          • #6
            That's an interesting technique, which I have not heard of before. This is the one I have seen to counter ABS warping: https://www.youtube.com/watch?v=DQu0ThBS4MY.

            Thanks for the hint about rotating to a face in Cura. This feature is very obvious in Prusaslicer but, to me at least, not even close to being obvious in Cura. Even when I finally located it, the icon is so non-intuitive I skipped it several times. Your statement that it does exist was the only reason I persisted and found. What on earth does a "skewing" icon have to do with rotating to a face????? Seriously?? And then, when you click it, it doesn't stay selected. Why the heck not? It took several minutes to figure out how it works. Even now, I'm not 100% certain I have it down pat.

            I tried the rotate to face on the printbed support arm and it did, indeed, seem to place the arm on the printbed without any air gaps so, again, thanks.

            In a small way, it is the fault of Cura. This feature should be 1000% more obvious, and it should work much more intuitively. I would have found it a long time ago if it wasn't so cryptic.

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            • #7
              Cannot say much about it as my "slicing/octoprint connect"-laptop does not support OpenGL 3.2 or so.

              That is why I don´t have that feature and not even the bottom slider where you can see the traveling/progress within a layer. My version probably lacks more features I only know about, because I have seen them in change logs.

              About the technique: I did not hear about that, too. A friend and I invented it somehow last year. And it works like a charm.
              Last edited by Geit; 11-01-2020, 06:04 PM.

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              • #8
                Originally posted by Geit View Post
                About the technique: I did not hear about that, too. A friend and I invented it somehow last year. And it works like a charm.
                Have you tried the clough42's mouse ears technique?

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                • #9
                  Originally posted by Ender5r View Post

                  Have you tried the clough42's mouse ears technique?
                  No, I want to print stuff and not tinker around with additional stuff. My way I can just switch Cura to ABS, load any model and set Z to 3mm. Done! Basically as fast as any other print and guarantied to work.

                  I saw that method a while ago, but since I have a fast and working method there is no need. They also print with PETG AFAIR.

                  ABS is far more aggressive. Just the dots won´t work for long prints. You need ABS-Glue on the glas bed, or the print will not stick at all. This foundation makes the bottom of the print ugly like hell and you need the same ABS-Glue color of the current print, which makes changing the color painful, as you need to clean the build plate completely. With my method it does not matter. You can have a black ABS-Glue covered glass bed and print snow white ABS. It does not matter as the lower 3mm are supports anyway.

                  Here the shocking image:
                  Click image for larger version  Name:	ANETA8_ABSGlue.jpg Views:	1 Size:	296.9 KB ID:	5560

                  As you can see the round "clean" area is where the last print was. The next step is to dump some acetone onto the clean area and use an ABS block to create a new coating and start the print.

                  Click image for larger version

Name:	TronXY_X5_PartCoolingFanMount_1.jpg
Views:	18
Size:	334.8 KB
ID:	5561

                  This was the print I did here.
                  Last edited by Geit; 11-01-2020, 07:24 PM.

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                  • #10
                    I had NO idea you could use sewage as printbed adhesive. Doesn't the smell bother you???

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                    • #11
                      Don´t worry! The ABS smell kills it all.

                      Works for years that way and the prints are great.

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                      • #12
                        Oh. I thought you were going to tell me your nose fell off years ago! 😇🧐💩

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