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  1. #1

    Can you please critique these prints?

    This was my first print. Not good. I think I had bad retraction settings.
    20170512_004622-1-1024.jpg

    I turned off my retraction and printed this one. Much better, but not as good as I would like it to be. I am having some layering issues. You see how rough the edges are?
    20170514_011525-1-1024.jpg

    I redesigned this L bracket and printed it on it's side just to see how it would come out and it came out a lot better. I kept retraction off and got a lot stringing/ gunk build up. I think my travel speed is 150 here? Not sure. You can see that the edges are still a bit rough
    20170514_025747-1-1024.jpg

    This was my last attempt. I turned on retraction and set the retraction speed higher and kept the retraction distant very low. I also increased my travel speed to 160. The holes came out great! Much better than any other attempt, but the layering sucks. It's so rough.
    20170515_145220-1-1024.jpg20170515_145145-1-1024.jpg

    One thing I have been trying to combat is that it appears that the machine to overlapping the infill with itself to much. Not the walls, but itself. Every time it infills a layer the finish is a a bit rough because it looks like the tip of the nozzle is plowing through the plastic some, which leaves these very fine raised areas. I tried changing the infill width, distance and it doesn't seem to make a difference. I'm going to mess with the flow some more to see if I can get better results.

    Does anyone have any idea why the out faces are so rough like whats seen in the pics?

  2. #2
    Staff Engineer Davo's Avatar
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    Considering the angle at which I expect this bracket to be under duress, I think printing it on its side (so that the layer boundaries are not perpendicular to the forces of stress) makes all the sense in the world.

    I would reenable the retraction, or perhaps half the retraction, and print at a slower speed, making no other changes, and see how that comes out.

  3. #3
    Yea, printing on it's side is the way to go. I was printing it the other way just to see what the outcome would be.

    As for speed of the print, im actually printing them slow. Wall speed at 15, infill was at 10 but i changed it to 15 and saw no difference there.

    It feel like its extruding slightly to much. I tried messing around with the flow but iguess ill keep messing around with it more.

  4. #4
    Technologist LuckyImperial's Avatar
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    Quote Originally Posted by CVRIV View Post
    Yea, printing on it's side is the way to go. I was printing it the other way just to see what the outcome would be.

    As for speed of the print, im actually printing them slow. Wall speed at 15, infill was at 10 but i changed it to 15 and saw no difference there.

    It feel like its extruding slightly to much. I tried messing around with the flow but iguess ill keep messing around with it more.
    Yeah, that's already a pretty slow printing speed. I agree that a reduced flow will help. Try 80% flow.

    Another variable you may factor in is temperature. If your temps are too high your nozzle will tend to over extrude a little. This is exasperated by slow printing speeds.

    Maybe try -10C on your printing temps and 80% flow.

  5. #5
    Whats a typical flow? Right now i am printing at 120! When i was printing at 100 it appeared that the extruder was starving for material.

    Ill mess around with it more and see what happens. Thanks.

  6. #6
    Technologist LuckyImperial's Avatar
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    Ideally the firmware of your printer should be configured so that 100 is typical.

    I print at 100 unless I'm doing 60mm/s prints (typically I do 35mm/s), in which I usually jack up my temps +10C and my flow to 110.

    My last tip is: The consequences of under extruding are less detrimental than for over-extruding. However, at really low speeds (<15mm/s) you really do have to be concerned about heat soaking the filament and causing a nasty jam.

  7. #7
    Ok. Ill take that into consideration.

    One more thing.... How do i keep the machine from infilling very small areas. I set the parameter for minimum area of infill, or something that, as 8mm^2, but it still keeps infilling these very small areas. I would much rather just have it fill it in the way it does the walls.

  8. #8
    Technologist LuckyImperial's Avatar
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    Unfortunately every slicer is different. I assume you're using slic3r, which I believe has a pretty obvious way to accomplish what you're asking for:

    http://manual.slic3r.org/expert-mode...l-optimization
    I would set it to 1mm^2.

    Why though? Why not let it infill the small area? If it's because of over extrusion...well, that shouldn't be a reason (properly fix overextrusion).

  9. #9
    Im using cura at the moment. Watching it infill those small areas it seems a bit crazy? It does the walls nicely and then.... Does this real crazy back and forth infill thing and then moves on the the next small area. I just thought it would be better to just wall off the tiny spaces.

  10. #10
    Engineer ralphzoontjens's Avatar
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    The infill can be related to your wall thicknesses not being a multiple of your nozzle size. So that it will venture in between two walls to fill in that tiny gap. The overall gap over the entire perimeter can then still be larger than the amount you specified. However it is recommended to produce solid walls for strength of course. For some models this zigzag infill works really well and can smoothen out the layer. It all depends on your printer and your exact settings, this is very specific. I recommend also adjusting the flow rate, typically 100 will work if you also accurately set filament diameter, and make sure your print speed is high enough so it doesn't keep the model too hot causing distortions. We are used to seeing planar surfaces so we will easily see imperfections in straight sections, what you can also do is improve the design to make it slightly curved. Printing on the side was a good call structurally, just keep the other strut there in place as well in case it will carry heavy loads, to prevent torsional unlayering. Just keep the 'support everywhere' option in place, it will be easy to remove.

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