Cura generates non uniform arcs leading to bad geometry

[louis_sckr 0]

Hello dear community,

 

I recently got myself a Ultimaker S3 and now the first big project is due. When slicing the part, I get arcs which don't match the geometry. At first I suspected bad export geometry / low resolution stl. When looking at the other parts though, I doubt that its geometry related as other arcs are printed just fine. 

Is there any way to get rid of this issue? I couldn't test wit a step file as the "free" version of cura doesnt support this but I have not the same issues with the part being sliced in Prusaslicer. There are some slight issues as well but not as much as in Cura.

Any help for better curvature would be appreciated!

 

Louis

jet housing.STL

[Slashee_the_Cow 451]

Hiya! If you could post a Cura project file .3mf (get it set up, then go to File > Save Project) that's a lot more helpful than just the model since it contains the information on your printer and the quality settings you're currently using.

[louis_sckr 0]

Thanks for helping, here is the .3mf

UMS3_jet housing.3mf

[Slashee_the_Cow 451]

It looks like the problem here is that your bits are in the grey area between being to fit X or X+1 lines... except with the number of walls in your quality profile it will only generate X normal walls, so there needs to be enough room for it to generate a line of whatever would go in the middle (infill or in this case skin).

 

I usually post my whole discovery process. If you want to get to the good bit, just scroll down to the bold red text below that says "TL;DR"

 

Your circular bits being a consistent 2mm width, if I increase Walls > Wall Thickness to 1.2mm, which will bump it up to 3 lines each side which quite accurately fits five 0.4mm lines:

Though obviously this approach suffers the collateral damage of adding extra walls everywhere which uses more filament and takes longer to print. You could use a modifier mesh to change the number of walls for just that bit... if it's just that bit... but that's a bit of a hassle that we shouldn't have to go through.

 

So what settings can we play with to try and get the results we want? Problem here is that you can mess with combinations until the 🐄s come home, and it's 12:30AM already here so I don't have time to mess with combinations. But I can go through a few of the relevant settings.

 

Walls > Minimum Wall Line Width: the guideline for line width is 60-150% of your nozzle diameter, which in this case means you can go down to 0.24mm which might make it inclined to thin walls that go in there.

Nup.

 

Walls > Wall Transitioning Filter Margin: This allows lines to get thinner or wider than the normal limit to try to keep a consistent number of walls. First I'll try increasing it to 0.2mm:

Still nope. Some of those lines look fat. What if I go the other way and set it to 0.01mm?

I think that just made it worse.

 

TL;DR: THIS BIT

💡 goes off:

Mesh Fixes > Maximum Resolution. Lower is better. It exists mostly because if you kept things too precise (close to the model) older printers couldn't keep up with the barrage of small movement commands. You have an S3. It can handle it. And you have it (possibly the default) set to ⅔mm. That's a big difference when our problem area is 2mm. I usually have it set to 0.1mm, and my printer is a cheap piece of crap compared to an S3, and cheap in a general context. But let's try 0.1mm:

Bingo! 😃

TL;DR: Set Mesh Fixes > Maximum Resolution to 0.1mm, or a bit lower if you're still having problems, I go to 0.01mm without any problems sometimes.

[louis_sckr 0]

Thank you so much man! This is BY FAR MORE than I've asked for! You've made half a research for me. Thank you for everything!!!