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Answered Any benefit to external perimeters first?

Discussion in 'Troubleshooting' started by Shane Simino, Dec 8, 2016.

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  1. Shane Simino

    Shane Simino Member

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    May I pick your brain some more? So I've been messing with External perimeters first to see if it gives me a better finish. I don't see a difference. I also have "avoid crossing perimeters" checked off. Wouldn't that kind of do the same thing? If it can't cross perimeters, wouldn't it start on the outside and work it's way in.

    My finishes are very nice, but sometimes I see a little bit of missing material it looks like. Maybe from retract and then starting on the outside. No matter what I try, I don't really seem to get rid of that issue. I'm using PLA mostly and here's an example attached. The dog's finish is very smooth, perfect on the sides and back. Look at the back of his head. Still smooth, but doesn't look like it's completely filled in. The smaller the print area, the more I see it. The printer is calibrated too. I don't believe this is under extrusion. I snipped a pic of my retraction because I did fiddle with that a long time ago and maybe I'm extracting too much? Thanks for taking a look.
    IMG_0739.JPG Capture.PNG
     
  2. Toro1966

    Toro1966 Active Member

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    If I'm not mistaken, the primary benefit of external perimeters first is to try and get the smoothest finish on the outside. Specifically, your retraction marks, if any, would be on the inside, not the outside.

    Looking at your object, what layer height are you using. Not very smooth from the pic. What I mean is that I can see your layers pretty good and they don't look like they meld together well. Are you sure you are not overextruding?
     
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    You might want to ping the people who wrote whichever slicer you are using.

    Generally speaking (very) this parameter will help with dimensions of holes since the outer perimeter is laid down first and then the inner ones so that any extra filament is pressed back away from the perimeter. This then makes the hole size more accurate.

    As for the rest -- too little data to hazard a guess :)

    There are certainly some surface defect/artifacts on there that I would not expect.
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Good point... When did you last calibrate the extruder?
     
  5. Shane Simino

    Shane Simino Member

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    Layer height is .2. That's a really close up photo. The dog is less than 3" tall. I'm not sure of anything. LOL. I calibrated yesterday and it was exactly 100mm for 100mm. Overextruding would look like that? I had under extruding problems before and the layers weren't melting together. My temp is currently 195. Here's another pic from a planter. Maybe this will help too. IMG_0740.JPG
     
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Visually that looks a lot better.
    Again, external perimeters first is only about increasing dimensional accuracy.

    Most modeler/printers I know just learned to adjust for the expansion (or contraction) of the filament and then design for what they are printing with :)

    If high levels of accuracy is an issue then SLA/DLP is a better choice than FDM.
     
  7. Shane Simino

    Shane Simino Member

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    So, what you're saying is, don't expect too much in a nut shell. Lol. I could go to a fine print, .1mm but it takes forever and really isn't justifiable for a toy. I'm really curious about the new R2. Accuracy is a lot tighter and then future dissolving material for the second print head would get rid of ugly support finishes.
     
  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    You can get rid of ugly support finish today a lot cheaper. Buy Simplify3D
     
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  9. Shane Simino

    Shane Simino Member

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    Really? That big of a difference?
     
  10. Geof

    Geof Volunteer Moderator
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    Hi Shane. Outside opinion (yes simplify rocks) but if you want to stick with the free software look for a cooling minimum time layer if the issue appears on smaller potions of the print but larger parts are good for your quality standard.

    In S3D its under the cooling tab (with fans and the such) I'm not sure where in other software it is as I havent used it in a very long time.

    I can speak to the dual material (soluable support material as well). Its not rainbows and unicorns :D. Its very difficult and the soluable support material sticks very well....to the point that you may have blemishes from the support material wisping into where the layer should go. Quite a nightmare to print, quite a nightmare to keep the spool dry so it doesn't go to waste...even more a night mare to do dual extrusion in general...even on a machine considerably higher priced and I assume better quality than the R2 (for the price point is where I'm making these assumptions, I have no hands on experience with an R2 and doubt I will)
     
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  11. Shane Simino

    Shane Simino Member

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    Thanks Geof. I think I'll take the plunge and buy it. Now you've killed my dreams about dissolvable material. haha. Um, how many printers do you have???? And what do you do? I have a machine shop and my Robo has come in very handy for work stuff, but I'll admit I use it for hobby stuff mostly. ;)
     
  12. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Too many :)
    I have too many and he has a lot more.
     
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  13. Shane Simino

    Shane Simino Member

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    Lmao. Oh sure. Throw Geof under the bus.
     
    #13 Shane Simino, Dec 8, 2016
    Last edited: Dec 8, 2016
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  14. Geof

    Geof Volunteer Moderator
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    Lol :) sitting at 17 but 8 of them are production job machines that will hopefully go away. Gets a little hot in there lol.

    I run a 3d print service (like most of us do) and do local repair and service.

    By day im a mechanic for a comercial print shop(paper) still, new job starts soon where its 3d printing all the time lol
     
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  15. Geof

    Geof Volunteer Moderator
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    Dont let me talk you out of trying anything if you want to... :) my standards are pretty high and the benefit to cost per print/headache didnt add up for me. It may be perfect for you :)
     
  16. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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  17. Geof

    Geof Volunteer Moderator
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    lmao! I accept it :(
     
  18. Shane Simino

    Shane Simino Member

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    Oh wow!!! That's crazy!
     
  19. Shane Simino

    Shane Simino Member

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    That makes sense. I want the best print I can get with as little headache as possible.
     
  20. Shane Simino

    Shane Simino Member

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    The new job sounds cool. Good luck. This is probably totally taboo, but what printer in your experience gives the best quality?(FDM printers)
     
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