Cura slicer puts unnecessary top and bottom layers! Help me understand!

[Strino93 1]

Dear Makers,

 

I've a problem with the slicing settings of CURA.

In Figure A is the model sliced by CURA 5.8.1 (tried with CURA 5.5.0 and is the same), while Figure B is the source GCODE that I have to replicate.

Can someone explain why the slicer puts top/bottom layers inside the model? I can't put top/bottom layer to 0 because I need them in other parts.

I've tried tweeking "small top/bottom width" but no canges to the preview.

 

Can someone explain if it's just a matter of CURA settings or the slicer (maybe the source GCODE has been made with other softwares)?

Thanks everyone.

wing_L_1_v6.3.3mf

[Slashee_the_Cow 480]

If you could post the source gcode file you're trying to emulate that would massively help here. Your Cura project uses a custom printer definition so I can only load the model from it (and not the printing settings, which are support of important)... also the model doesn't seem to load with the internal geometry.

 

My stab in the dark would be to increase Top/Bottom > Small Top/Bottom Width. Any surfaces below that width will be printed using walls instead of skin.

[GregValiant 1,409]

  

 

The model was designed with single-sided surfaces.  They have no thickness and Cura is interpreting some of the geometry to require Tops/Bottoms.

 

I sliced this with the SmartAvionics (@burtoogle on this forum) fork of Cura.  It's my go-to for things that look like they will need to be spiralized and is based on UM Cura 4.x.

This slice was not spiralized but rather was sliced with "Surface Mode" set to "Surface".

The ribs do not touch the walls (see the gaps in the image below).  That would seem to be an instant failure point with a regular filament, If you are printing with one of the "expanding-light-weight" materials, then it might work as the gaps might go away.

 

You can see that the blind hole coming in from the side intrudes into (what I assume is) the spar hole.  If that is indeed what it is - that's going to be tough to clean out.

 

This is a difficult model to print.  I think much will depend on how the material acts during printing.  It will be on the material to fill all those gaps so the wing ends up as a hole piece and not just a bunch of separate entities that fall apart when you take them off the build plate.

 

 

 

[Strino93 1]

Here the original STL file, the source GCODE to recreate and my current profile settings.

 

@GregValiant I dont think the mode is supposed to be sliced as "surface", since the original GCODE has some thickness and top/bottom surfaces in some area.

 

The model is a section of an airplane wing, so it is mainly empty with some structural parts inside.

It is supposed to be printed in both PLA and Low Weight PLA, therefore it should not rely solely on foaming of the printed material to stick together.

 

My main issue is that the original GCODE loaded on CURA 5.8.1 is different from the same STL file sliced directly by CURA.

I would like to know if it is possible to recreate with minimum changes the GCODE.

 

@Slashee_the_Cow changing the Small Top/Bottom Width only modify the pattern of the top surfaces from straight profile line to line at 45°.

Current Profile.curaprofile wing_L_1_v6.3.STL wing_L_1_v6.3_g1.gcode

[Strino93 1]

Update.

 

Changing the layer height results in some "bottom" layer to be removed.

Still there are areas where the "top" layers are printed.

 

Image A is with a layer height of 0.15mm, Image B is with the standard 0.2mm height.

 

I dont understand what impact the layer height has since there are no settings involving the slope angle on "top/bottom" menu.

[Strino93 1]

Update.

 

It seems I've found the solution in increasing the "top/bottom > skin removal width" setting.

Setting to 1.5mm it removes all the unwanted top/bottom lines.

Image A with the default value of 0.4 mm

 

Image B with 1.5 mm value

 

Still have to check if other regions are removed or not, but I think this is the parameter to be tweeked to obtain the original GCODE.

[GregValiant 1,409]

Ahhh.  I hadn't thought of that.  My brain was stuck in Surface Mode even though it isn't being used.

 

That original gcode was sliced with Cura 3.5.1.  That was a few years ago.

I created this project in Cura 4.13.1 as it is the closest to 3.5.1.  I thought the slice looks a lot like the one you want to duplicate.

 

GV Ender3Pro_wing_L_1_v6.3.3mf

 

I was able to generate a quality profile from the Gcode you provided.  My printer doesn't have a "Normal" quality profile so I changed "normal" in the Gcode to "standard" and was able to successfully import the gcode as a profile.

 

I wasn't able to get Cura 5.8.0 very close to what you are getting.  The prints are 5grams heavier as well.

 

 

 

 

[GregValiant 1,409]

3.5.1 is still available for download HERE.  Going with that original software might get you closer to the proper settings to duplicate the "look" of that gcode file.

[Strino93 1]

@GregValiant can I ask you if the "top/bottom > skin removal width" in your settings is set to default (0.4 mm)?

I've tried to open the .3mf file but using CURA 5.8.1 gives the same results as before.

 

I think they changed how the slicer see some parts of the STL during the updates and what was automatic in CURA 3.5 is a lot harder in 5.8.

 

Anyway I'll try to print using my settings in CURA 5.8.1 and if it doesn't work I'll install CURA 4.13.1 and use your settings.

[GregValiant 1,409]

Yeah, it was 0.4.  I changed it to 1.5 but I don't really see a difference.

3.5.1 was released in October of 2018.  A 2018 wing or fuselage would have been designed to slice with what the current software at the time would be (Cura 3.5.1, Simplify3D, etc.).

Surfaces are treated differently in the newer versions of the slicers and consequently the way airplane parts are designed (to be printed) has changed to take advantage of things like "Spiralize Outer Contour".

 

[GregValiant 1,409]

Sorry.  Double dip response.

Edited November 14 by GregValiant