Question Outer layer missing in one section of model in layer view

[patben 1]

Hey everyone, New here! 

 

I am trying to print a sphere, that has a pretty thin wall as it is going to be a lamp. I have had no problems with models with thin walls before but this time, when checking my layer view in Cura it appears there is a chunk missing out of the outer layer all the way up the sphere. I've tried a few things suggested in similar questions on here, like thickening the wall by .01 mm and adding horizontal expansion of .001 but nothing seems to make a difference. I have noticed that even when I rotate the model by 90 degrees the missing section of the outer wall is still at the back of the model reletive to the print bed. One would think if it was an issue with the actual model the missing bit would move as well when the model is rotated but it's always in the same spot. It's probably something simple for all you more experienced 3D printer users! I'm not even sure it's anything I need to worry about.

 

Thank you for any help anyone can provide.

[CarloK 203]

What Cura version are you using? This might have been fixed in a newer version.

If you are willing to share your project we could have a look and see if the issue is reproducable.

 

Also, since you are printing at 'Ultra fine' resolution, you might want to try out the new Cura beta release with Arachne engine. This next generation of Cura will be able to print details better.

 

[patben 1]

1 hour ago, CarloK said:

What Cura version are you using? This might have been fixed in a newer version.

If you are willing to share your project we could have a look and see if the issue is reproducable.

 

Also, since you are printing at 'Ultra fine' resolution, you might want to try out the new Cura beta release with Arachne engine. This next generation of Cura will be able to print details better.

 

 

thank you for your reply! I am using Cura 4.11 but just downloaded the updated version after reading your post. I'll give it a go and report back!

[patben 1]

ok so I downloaded the newest version and still have that strip with no shell at the back, regardless of rotation. I've basically kept all settings the same, didn't fiddle much with it (unless I changed something and have forgotten that I did). I haven't put supports in yet because I want to figure this out first.

 

I've attached my Cura project file. 

 

MSMV2E3D_sphere.3mf

[CarloK 203]

I opened your project in the Arachne Beta2 and see also a missing part at the back. It looks better than in your screenshot, but not printable.

 

There might be a problem in Cura, but what is your intention? Now it looks like a very thin walled ball. The walls of this ball are not of equal width everywhere, that's originating from your model.

 

Might I suggest that you create a 100% solid object? Then, in Cura select to print with 0% infill. Select the number of lines you want for the outer wall to select the thickness.

Or, likewise, but use the 'spiralize' option to get an outer wall of 1 line thick. With a 0.4mm nozzle you can select the line width up to 0.6mm.

A similar topic for hollow objects was discussed here:

 

[GregValiant 1,287]

He has Coasting enabled.  The gap is the coasting move and since there is no extrusion along that path the preview just shows as a travel move along there.  I suppose technically it is, but it will print.  It is a pretty long coasting move though.

 

I don't care for coasting.  It seems like there is always an under-extrusion at the start of the next extrusion.

[patben 1]

1 hour ago, CarloK said:

I opened your project in the Arachne Beta2 and see also a missing part at the back. It looks better than in your screenshot, but not printable.

 

There might be a problem in Cura, but what is your intention? Now it looks like a very thin walled ball. The walls of this ball are not of equal width everywhere, that's originating from your model.

 

Might I suggest that you create a 100% solid object? Then, in Cura select to print with 0% infill. Select the number of lines you want for the outer wall to select the thickness.

Or, likewise, but use the 'spiralize' option to get an outer wall of 1 line thick. With a 0.4mm nozzle you can select the line width up to 0.6mm.

A similar topic for hollow objects was discussed here:

 

 

Thank you for the tips! Unfortunely I need to retain the varying thickness of the wall to obtain the look I want once the model is printed (I want the sphere to appear and feel smooth on the exterior but added texture to the interior to vary the lighting once lit) I tested it by printing a chunk of my sphere and putting it infront of my LED and loved the look of the light so want to retain that texture so don't want to simply print a hollow sphere where the inner and outer walls are the same.

[patben 1]

1 hour ago, GregValiant said:

He has Coasting enabled.  The gap is the coasting move and since there is no extrusion along that path the preview just shows as a travel move along there.  I suppose technically it is, but it will print.  It is a pretty long coasting move though.

 

I don't care for coasting.  It seems like there is always an under-extrusion at the start of the next extrusion.

 

Thank you! I had completely forgot I turned on coasting forever ago for something else as recommended by the person who made the model and forgot. I turned it off and now it's just the thin starts! I'm gonna give it a try tomorrow and see how it goes!

 

I also wanted to take a second and thank you both for being so helpful, understanding and friendly, as someone who is still very noob at 3D printing it's nice to find a forum where members are understanding.

Edited November 29, 2021 by patben