When slicing the back part of this model with Support Type set to tree(auto) and everything else default, notice that 2 of the 3 wings (or whatever they are) have supports for the little ridges, but one of them doesn’t.
The attached images shows the one without supports on the left and one with supports on the right. The one closest to the viewer has supports, though they are blocked from view.
It’s important to note that the automatic features of the slicer software only gets you so far. Then it’s up to you to tweak everything you don’t like.
The support algorithms make decisions based on mathematical calculations. I don’t know what the precision is(16 or 32bit) and for discussion purposes, it’s not important. However, when the calculation is performed for let’s say a placement of a tree, if your calculation let’s say is the difference between 0.0003 and 0.0006, that’s enough difference between rounding up and rounding down which could be tree or no tree. Also remember that an STL file is almost never 100% symmetrical as far as the computer sees. The mesh triangles that creates the file can have tiny deviations that will also influence the slicer’s calculations even though we can’t see it with our own eyes.
If it is interfering with your print, a simple experiment during slicing is to rotate the body 5 degrees and see if it slices differently. Alternatively, you could just use the support painting tool and force the trees to attach manually and where you feel they belong.
Thanks for the response. I did look at the manual support painting but there are so many little overhangs, I figured I’d probably miss some of them and ruin the print. When I use the normal supports, it adds a lot more support (+2 hours and +30g). I think I’m just gonna go with normal supports anyway.
I do appreciate the detailed answer. I just thought this could be useful test data for the developers as they fine tune the tree supports.
Painting supports is definitley a tricky thing and there is an art to it.
If you haven’t tried it out, I’ve had goo look with using the Sphere and Flood features. The flood I love when I zoom in. It let’s me pick a single pixel and then paints every pixel adjacent to it. If you have overhangs turned on when you do it, you can also get more adjustment through dialing in the percent. Likewise, Sphere let’s you reach behind nooks and crannies you can’t easily see.
