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Random layers offset problem


helpMe2

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Posted · Random layers offset problem

If you could provide the .3mf file (go to File > Save Project in Cura) that would help. It looks like a problem with extrusion, possibly around the Z seam.

 

Some more information would help - have you sliced other things successfully before using the same software and the same settings? Has anything changed on your printer's end - firmware update? Different filament? What printer is it?

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    Posted · Random layers offset problem
    9 minutes ago, Slashee_the_Cow said:

    If you could provide the .3mf file (go to File > Save Project in Cura) that would help. It looks like a problem with ...


    Sorry I won't have access to the file until tomorrow. 

    I'm not sure it's the Z seam, these lines go around the part. And interestingly the cylinder part doesn't have this problem.

     

    I sliced the cylinder (as in the image above), with the same settings and it turned out perfect.
    Nothing changed regarding firmware. Same filmanet. 
    Printer: Guider II by Flashforge

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    Posted · Random layers offset problem

    Still sounds like an extrusion problem. Cylinder would be fine because it can just do a constant flow as the print head drives round in circles. Cube(?) has to deal with the jerk of going around corners, and it probably has a lot more travel moves (especially depending on your line and infill settings). To make doubly sure it's not a problem with the slicing (at least not dimensionally), if you can upload the g-code when you have a chance I can have a look through it and make sure all those lines are where they're supposed to be (and not using very different extrusion).

     

    FWIW, it generally doesn't hurt to try the latest version of Cura if you're using an older version (they'll happily live side by side) but in this case I definitely wouldn't put all my eggs in that basket.

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    Posted · Random layers offset problem
    11 hours ago, Slashee_the_Cow said:

    Still sounds like an extrusion problem. Cylinder would be fine be...

    Attached is the 3mf file and profile.
    Cura version: 5.1

    Note: nozzle size is 0.8 mm. Outer wall line width is set to 1.2 mm. I assumed the outer wall was getting pushed out by inner walls, and attempted to create a small gap between walls, but no luck.

    I have tried the latest Cura, but the results are worse. 
     

    Profile.curaprofile T8.3mf

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    Posted (edited) · Random layers offset problem

    Update: I printed a few tests. 

    Test 1: Hollow rectangle (no radius on corners) and 2 wall count
    Result: 95% perfect

    Test 2: Hollow rectangle (rounded corners - same radius as real part) and 2 wall count
    Result: 80% perfect (30% better than the real part)

    Concluding 2 things from this. 
    1. The print head isn't decelerating when taking the rounded corner (2.5 mm radius), causing the material to overshoot, and somehow carries through the rest of the wall.
    2. The inner and possibly infill walls are somehow causing outer wall to overshoot material.
     

    Edited by helpMe2
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    Posted · Random layers offset problem
    6 hours ago, helpMe2 said:

    1. The print head isn't decelerating when taking the rounded corner (2.5 mm radius), causing the material to overshoot, and somehow carries through the rest of the wall.

    This is in preview mode, with colour scheme set to Speed:

    image.thumb.png.cdd65b62017cafccc95d702b1ed8136e.png

    Yeah. She definitely ain't slowing down for corners. I tried playing with the acceleration and jerk settings and didn't seem to have much influence.

     

    6 hours ago, helpMe2 said:

    2. The inner and possibly infill walls are somehow causing outer wall to overshoot material.

    Possible but I'm not sure if it's likely. Colour scheme set to Line Type:

    image.thumb.png.1ed4794d1ec5cb8b748ff9e09711054e.png

    The problem is that the the walls around the cutouts are also considered outer walls. You do have Walls > Outer Wall Wipe Distance turned on, which may have an effect, especially since your Z seams are right in the corner.

     

    So what settings can we play with to try and fix it?

    1. Walls > Outer Wall Wipe Distance: Can cause what looks like (but technically isn't) a bit of overextrusion it's still oozing a bit over an area it's already done. You can try turning that off.
    2. Walls > Z Seam Position: Being right on a corner it's going around at full pelt doesn't do it any favours. If you move the Z seam position somewhere where it'll finish slightly inside on a wall that's probably better.
    3. Material > Flow > Outer Wall Flow: I notice you have it set to 95%. While a small change like this shouldn't have too noticeable an effect, any reduction does make imperfections on the inside more noticeable (although maybe you were having trouble with overextrusion on the outside, so you might have to figure out which is the lesser of two evils).
    4. Speed > Wall Speed: I know. It pains my heart too to suggest slowing it down. But as a general rule, the slower you go (within reason) the more accurate your print is going to end up.
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    Posted · Random layers offset problem
    1 hour ago, Slashee_the_Cow said:

    Walls > Outer Wall Wipe Distance: Can cause what looks like (but technically isn't) a bit of overextrusion it's still oozing a bit over an area it's already done. You can try turning that off.

    I appreciate the suggestions and help 🤝

    1. I've tried lower and higher wipe values, it seems either one cause more issues. 
    2. That's a good point and worth a try. 
    3. Also tried higher and lower flow values, but no improvements. 
    4. Interestingly, higher speeds seem to have the best results. I get a lot of pit marks with lower speeds. 

    Seeing as the only variables between a 50% and 95% perfect print are rounded corners and inner walls, Id be nice to find a workaround for decelerating corners. 

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    Posted · Random layers offset problem

    Not corner related, but something I just noticed: it's pretty hard to see because none of the press photos actually show the thing with filament loaded, but does your printer use a Bowden extruder (filament loads into extruder, usually on side of printer, then runs through a tube to the print head)?

     

    Because if it does, I'm wondering about the retraction settings. 1.8mm retraction at 35mm/s is not a lot for a Bowden extruder. As a comparison, the default profile for an Ender-3 / Ender-3 v2 is 5mm at 45mm/s. My Ender-3 v2 Neo I had at 6.5mm since it came with the dual wheel metal extruder upgrade as stock, probably a bit overkill but it worked so I left it as is. My Ender-3 V3 SE which has a direct drive extruder (extruder sits above print head and feeds directly in, requires a lot shorter retraction, and it's set to 0.8mm at 40mm/s. If it's not retracting far enough (or quickly enough) then the head could still ooze a little bit when it shouldn't be getting any filament at all.

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    Posted · Random layers offset problem
    36 minutes ago, Slashee_the_Cow said:

    Not corner related, but something I just noticed: it's pretty hard to se...

    Im using a Guider II by Flashforge, which has a direct drive. 
    It could affect oozing, but considering the other print tests, its not likely. 

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    Posted · Random layers offset problem
    19 minutes ago, helpMe2 said:

    Im using a Guider II by Flashforge, which has a direct drive. 

    Ah. For whatever reason Cura was assigning it to a printer profile which presumably had been there because I was testing someone else's file. Given my recent experiences, I now pity that person.

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