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I'm trying to print a gear for a robovac deal.

The issue I'm having is with gaps between the walls of the top part of the gear. It needs to have the corners filled to provide stability or else the tabs easily snap. I've tried adjusting the nozzle size, line width, filter gaps and print thin walls but seems to slice with variations on the same issue. Is this a Cura issue? Is there anyway to slice and print this to fill those gaps?

gear with gaps between walls

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    $\begingroup$ What does the original model look like? It looks like they took a cylinder object and binary subtracted a cube leaving the walls too thin near the corners. This looks like an extremely small part... $\endgroup$
    – Ron Beyer
    Dec 16, 2020 at 23:38
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    $\begingroup$ Hello, thanks for the response. I've messed around with it a bunch more today and I believe that the wall is simply too thin on the corners to be printed correctly. I ended up loading the model into blender and extruding the edges along normals to make it thick enough. Once it printed, I threw it on a little spindle and then used a drill and some sand paper to slowly remove material till it fit the bearing it needed to go into but left just enough to connect the edges. The bearing does compress all the sides so I guess it could work even with the little gaps. $\endgroup$ Dec 17, 2020 at 2:35
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    $\begingroup$ Using smaller line width may work, but Cura has a bug whereby it makes no difference unless you also enable printing outer walls first. $\endgroup$ Dec 17, 2020 at 14:39
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    $\begingroup$ @R..GitHubSTOPHELPINGICE - thanks for the response, I will give that a go. Good user name! $\endgroup$ Dec 17, 2020 at 17:57
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    $\begingroup$ also, print thin walls can help...or Thickening the area in the model. $\endgroup$
    – Trish
    Dec 17, 2020 at 18:19

2 Answers 2

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The problem isn't Cura, rather its the precision of the 3D model. If parts of the model is smaller than the line width the model cannot be printed. A solution to this would be to increase the thickness of the cylinder, decrease the size of the square or reduce the line width to allow that region to be properly fabricated, another solution would be to decrease the line width (line width option) however, keep in mind that you should not reduce the line width beyond the nozzle hole size (nozzle hole > line width). As mentioned before, if the model requires sections that are smaller than the line width, Cura will ignore it. From the image you provided it would seem that the corners are extremely close to the wall of the cylinder which prevents Cura from making a extrusion path, the reason of which I explained above.

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  • $\begingroup$ Welcome to 3DPrinting.SE! Please remember this is not a forum of threaded messages, so I've removed the comment as an answer. The Ultimaker printers default profile have line width smaller than the nozzle hole size, this is not an error but is used for a better quality (explained in their forum), so although I agree on the line width not to be smaller than the nozzle hole size, you can do that to some extend. Depending on the model, tuning the line width might be very useful but take care in not making the line width too small. $\endgroup$
    – 0scar
    Jan 4 at 12:08
  • $\begingroup$ I personally prefer to print 10% wider than the nozzle. $\endgroup$
    – Trish
    Jan 4 at 14:21
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You can fix it by changing Experimental > Slicing Tolerance > Exclusive

Cura screenshot of a model with the Slicing tolerance set to Middle

Cura screenshot of a model with the Slicing tolerance set to Exclusive

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