Cura makes many short lines when it should be one longer straight line

[Bill_D 0]

When slicing a model that has some flat surfaces inside, the slicer creates that portion of the layer with many small segments of lines.

Photo 1shows the "interim" stage, and 2 shows the end result. (Each of the "blank" areas have a wall or some feature that appears a few layers above or below that current layer.) The next layer is turned 90 degrees but still leaves the same blank spaces to fill in.

 

Is there some way to get it to print the 100 or so lines in one pass instead of breaking it up into so many short lines, with all the associated 'travels' and retractions?

 

TIA

 

 

 

 

 

[GregValiant 1,409]

If you would use "File | Save Project" and post the 3mf file here that may give a clue.

[Bill_D 0]

Here is the 3mf file.

I tried a layer height of 1.0, and that section of that layer then prints with the longer lines, as one would expect it to print. (But the print time goes from 6 hours to 9..) A Layer Height of 1.5 or 2.0 both slice with the shorter lines.

 

Cheers

Bill

Battery Socket.3mf

[Bill_D 0]

Thoughts Greg? Anyone?

[GregValiant 1,409]

Bad model.

Your model from the 3mf file is on the left.  I exported the model as an STL file and uploaded it to Service.Netfabb.Com (Autodesk site for stl repair).  The repaired model is on the right.  You can see the issues with your model.  It looks like some surfaces are facing inside out.  Parts of the model get treated like they are hollow.

 

Here they are sliced together with your profile.  This is layer 14 and you can see how much difference the bad surfaces caused.

I'll include the repaired file.  Service .netfabb.com is free but you need to set up an account (also free).

 

You will notice that your bad model looks different when sliced than my bad model.  It has to do with the way the part is orientated on the  build plate.  I don't know why that is true but when it happens its a pretty sure sign that there are errors in the model.  

 

490051003_BatterySocket_fixed.stl

Edited May 18, 2021 by GregValiant

[Bill_D 0]

Thanks Greg.

 

This model was imported direct from Solidworks. I see that the STL model does not contain the internal structure that I created in the SW model, but just the visible "outside" surface. That does indeed change the slicing path!

 

Is it better to use an STL file type into Cura instead of direct from SW?

 

I will take a closer look at this this evening.

 

Thanks for your help!

[GregValiant 1,409]

One of the native-to-Cura file types is STL.  There are plugins in the Marketplace for SolidWorks, Fusion, etc. but I'm not familiar with them.  It takes about 15 seconds to export a model as an STL from my Win7 desktop and then open the STL in Cura on my Win10 laptop.  Slicing takes a bit of time and then the print then takes 3 to 15 hours to complete.

I'm running an old version of AutoCad Mechanical Desktop.  Parametric models need to be exploded to 3d solids and then exported as STL's.  I have never had a bad model doing it that way although I have butchered some designs that needed serious rework.  Everybody wants a single app to handle everything but I'm a fan of apps that "do one thing and do it right".

Cura is a slicer.  SolidWorks is a modeler and assembly modeler as is my AutoDesk app.  I write macros for AutoCad and it does tricks for me and I like that.  I don't need that level of functionality from Cura (or PrusaSlicer, or IdeaMaker), I just need it to slice things so I can print them without any issues.

[Bill_D 0]

Thanks for the info and the link to netfabb. I tried "fixing" an STL that I had exported from SW, and it sliced pretty much identical to the one you sent me.

 

I had done an early test print of this model, and I didn't like the way one of the horizontal surfaces printed, so I hollowed out the model so I could design the internal structure to better support that horizontal surface (which came out perfect, btw). The hollowing would be why all of the walls slice as 'external' on both sides of the wall.

 

A couple of observations about the "fixed" STL's:

- the fix only looks at the external "visible" surface, so any internal structure (hollowing, fillets, supports, etc) is ignored;

- walls are printed to the set width in a horizontal direction, so a slanted wall is not a 'true' thickness;

- it still prints some very short lines that could/should be joined to longer lines;

- definitely, in some aspects, the slicing pattern on the fixed STL is more efficient and concise than my SolidWorks model.

 

 

 

Thanks for the discussion and comments!

 

Cheers

Bill

Edited May 19, 2021 by Bill_D

[GregValiant 1,409]

Do you happen to have Coasting enabled?  That will leave lines that look like they don't connect in the preview but it's because the lines show extrusion moves and when coasting starts the extruder stops and so the rest of the line doesn't show up in the preview.

Regarding angled surfaces, Cura is slicing "sections" and so a wall that is 3mm thick and at a 45° angle to the build plate would print in the plane of the slice at 4.24mm wide.  That's the plan anyway.

[Bill_D 0]

Coasting is not enabled. You can see in the lower red box in the screen shot above that the extruder is starting to fill in the short lines.

 

The walls in this model are no more than about 40 degrees off vertical, so maybe that isn't steep enough to invoke additional lines. But the number of lines across a wall never exceeds the number that is in the print settings.

 

Cheers