I can’t figure out what is causing these defects in BS. The original model does not have them nor are they present when I import the model into BS. There is a setting (that I am unaware of) which is causing this. Any ideas on what might be culprit this or how to fix? It adds these defects after the slice.
Hi, yes, I’ve seen this before on some STL models I’ve downloaded, even using the default print profiles they came with. It boils down to resolution, essentially, on very thin features. Resolution of the printed lines certainly (layer height and line width), the original STL model, and to some extent the Quality → Resolution setting… which you could try reducing or increasing as a quick fix. Switching the wall generator can sometimes help. Changing line height/width is probably the most direct way to influence the issue, though sometimes that’s not great for the rest of the model. Adding modifiers to those areas to change layer height or line width more selectively could also be an option. In one case I chose to edit the mesh model and clean up the affected edges manually so they printed better (made them less tapered, IIRC).
HTH,
-Max
Thanks Max, my line height is set to .1mm.
I am also using Arachne. I did some experimenting and I am not getting ideal results. It appears the “Outer Wall” setting is the issue.
I tried to use “Layer Height Modifier” for layers 240 to 245 but it didn’t work so had to change layers 240 to the top. Problem is not, it seems to change the texture/color of the model and you can see where the change occurs.
Still had weird geometry only changing 240 - 245
So had to change all from the layers from 240 to the top but then you can see where the change occurs
Any way to get better results?
I designed this model in Fusion360 and don’t see any issues with the mesh. Importing it into BS, it looks ok. It is when I slice then the problems arise.
Ah it’s your own model, cool. The basic issue, it looks like, are those sharp edges at the top. The printer can only make lines so thin and there’s basically no way to taper to a zero width/thickness completely. So the slicer ends up making compromises.
I’d decide the minimum thickness of the edges that I could live with (for the design) and round those off in Fusion. The printer can print lines a bit thinner than a nozzle diameter, but those lines are going to be weaker (because they’re not getting squished down to flatten out). It may make for a thinner but weak edge. Arachne wall generator will adjust the wall line thicknesses automatically to a certain degree, which is more flexible, but can lead to some weaker lines. If you wanted a thinner but still strong edge, you could consider using a .2mm nozzle, though of course that would slow down the rest of the print quite a bit.
The other workarounds like changing layer height all have their down sides as well, as you’ve observed. Ultimately we have to work/design within the confines of printer/FDM capabilities.
-Max
Those features look real thin. Slicer is probably ignoring parts that it can’t produce. You’ve got control of the model, if those thin/sharp parts are under 0.80mm in your design, you might want to bolster them up. I generally go for 2 wall widths as a minimum design [0.80mm] but you do you
Gotcha, that makes sense.
The way the object is modeled, this is a cutout using another object.
There really isn’t a way (that I know of) where you can adjust the edges after the cut. I may play with the layer height to try and get it to print more cleanly. Or just sand it I guess but I was trying to avoid doing that.
Could you apply a fillet to the resulting edge, after the cut? That should create a flatter surface for printing. The “tangent” setting on the fillet tool can also be used to flatten out the curve some more, if needed.
-Max
This is cool. I appreciate the help. I enjoy learning more about the process.
Let me try the tangent tool, I have not used that yet. I can also try fillet to see if that will work.
Also, on a side note, I tried .2 layer height and it looks like it helped quite a bit. So if I were to increase the layer height and try and maintain a smooth surface on the model, would that be the “Ironing” settings?
Ironing is really for more flat top surfaces, I’ve not tired but I really doubt it would improve edges at all (if you can even get the slicer to iron such a small area).
The .2 mm height may be fine already? It always looks “worse” in the slicer preview than IRL. You could print a small portion as a test (cut off a piece in the slicer). I do that quite a bit when experimenting / dialing in a part, definitely saves a lot of time and filament.
That “tangent” setting I mentioned is part of the fillet tool, just to clarify. Pretty sure that’s what it’s called, anyway… 
It controls the overall curve of the fillet.
-M
Gotcha, ok thanks for clarification on the fillet. I just started with Fusion and this is the 2nd model I have ever done so still learning. Appreciate the tips!
All the nuances with modeling and printing are very interesting.
I just did some testing and found something unexpected.
I quite Studio and started over from scratch, Wall generator was set to “Classic” and this is what happened, it seems to be ok even for layer heights down to .1
What do you think?
Cool, yea, switching wall generator was in my initial list of things to try
Arachne will vary the printed wall line widths within a certain range, to create a more accurate overall wall/part thickness. Whereas Classic will stick to the set wall line widths and the slicer will fill smaller gaps, to maintain dimensions, with other lines types (if needed). So with Classic, the slicer sees those edge lines are just too thin to print and ignores them, whereas Arachne will try to “make it work” even if the final result is funky.
-Max
Very helpful, thank you sir. Yep, totally missed that recommendation! Thank you!
Is there a way to mark this question as solved?
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