3D Printing Forum

Hi guys,

In the pursuit of the highest quality prints possible, I am trying to minimize the appearance of the perimeter seam.

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First off, as a survey:

• -Would you say that your seams generally bulge outwards, pucker inwards, or both? (sometimes the seam looks like mini cleavage, with slight bulges on either side of a small divot) (It is definitely best to print with the seam location set to "back" or "aligned", so that you can see more clearly.)
  
  -What machine are you using?
  
  -What slicer and version are you using?

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For me, the seam is a slight dimple in the print skin, using the new Cura 2.1.2 (which is awesome if you haven't tried it!). I felt that this could be addressed by adding an overlap between the start and end points of the perimeter. On Github, we hypothesized, and disagreed on why it would or wouldn't work. So I decided to just test it experimentally.

Because perimeter seam appearance depends heavily on how slicers compute them, results are slicer specific. Even if you don't normally use the new version of Cura, you can still help test the feature. All files, including the control, were based on Cura 2.1.2 gcode. The more machines we can get to post results, the more we can see how global / specific the results are.

I made a very simple test of a hollow test cylinder (just a few perimeter loops):

• -The control is without any modification
  
  -Overlap_0.2 is the above file, with additional print moves added to the end of each perimeter loop, which extend the loop by 0.2mm, in the correct direction. Followed by 0.4mm, 0.6mm and 0.8mm overlap files.

Here are the results on my printer (a heavily modified UM):


https://cloud.githubusercontent.com/ass ... 9756df.jpg


I would love to get a good spread of results , across different machines, and that's where you guys come in. As long as you are running a 0.4mm nozzle, this code should print just fine with PLA. If you want to print other material, feel free to change the temp (just make it equal across the tests).

Just make sure to label the prints as they come off the machine. If you are able to get decent quality photos of the tests, that would be awesome. I used a piece of tape to hold them all together for my photo, which definitely helps the comparison. Even if you struggle to get an up close photo, some descriptive feedback would be helpful too. Just describe what you see when looking at the seams, and checking them with your fingernail.



If we can demonstrate that this provides improvement for most people, I think it will be added to Cura. Here are the gcode files:

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For Ultimaker Original (and other Reprap printers) running 2.85mm filament:
https://dl.dropboxusercontent.com/u/609 ... verlap.rar

For Ultimaker 2 running 2.85mm filament:
https://dl.dropboxusercontent.com/u/609 ... ap_UM2.rar

For Ultimaker Original (and other Reprap printers) running 1.75mm filament:
https://dl.dropboxusercontent.com/u/609 ... 1.75mm.rar  (These files use the flow override firmware function to convert filament diameter)

Another person's results (not an Ultimaker)

I reprinted all tests last night to include the .6mm and .8mm overlap tests in my results.

For me, I would say a 0.6mm overlap gives the best result.

Another person's UM2 results:

What an interesting experiment....I'm cranking out some large prints lately but can take a crack at your experiment in the future

Let me know what you see.

(I'm from Maine originally)