Infill structure on the top internal layers

[MatejEU 1]

Hi, I'm a new member here and I have to say that I really enjoy using Cura. I gave up on Simplify3D after spending +30 hours on fine tuning my profile in it and still not being able to hide, at least good enough, the z-seam on my models. Cura solved that, where possible ofc, with the hidden seam. Bravo Cura! Bravo developers!

I have an issue with the infill structure being added on the top internal layers, which are already finished. I have actually found a remedy by using search, here.
|Robert| advised on using a lower number of top layers overall and it worked, I've reduced from 4 to 3 and that was it. But, why did that work and what if I want to use more top layers to increase strength and improve the finish a bit? That top (infill) layer did offset three top layers down, it didn't replace one of them. Also, in the top left corner on the right side of the attached image, you can see that it didn't repeat the same behavior on that top surface. After I saw that, I played with the "Top skin removal width" feature which did change the outcome when I lowered the value, but it didn't help overall. That one top surface might have different dimensions in the actual model or something like that.

Thank you for your help =)
 

[gr5 2,167]

Anyone who reads the above post FIRST FOLLOW HIS LINK TO CARIFY!

 

Well this part is very different than the other part which had sloped sides.  This part seems to have mostly vertical sides so it seems safe to increase top/bottom thickness for this part.  You are going to learn that you have to change slicer settings for different parts for different reasons (otherwise there would be no need for changing the features).

 

So:

1) It seems like you can increase top/bottom thickness for this particular part.

2) Why did you want to get rid of it in the last part anyway?  Were you just trying to save time?  I mean it's invisible inside the print anyway, right?  Or was it ugly when people turned the part over and looked from the bottom into the infill?  This part in this topic though is solid so why do you care about the extra infill?  It *does* have a purpose - basically it is supporting the future shells coming up in a few layers time.

 

Maybe I don't understand what you mean by "top internal layers".  

[MatejEU 1]

Hi gr5, that is a fidget (cube) model where everything will eventually get turned to the outside, as you fidget with it  Those top surfaces aren't a structural surface for the layers above them, that's why I call them "top internal layers". I've attached another image. I'm a complete noob with Cura, so there is a good chance that I'm misinterpreting something here.

Edited January 6, 2018 by MatejEU

[yellowshark 153]

Hi I would like to help but I am really confused here as to what is going on here. You say "I have an issue with the infill structure being added on the top internal layers, which are already finished". There is no such thing as an internal layer; a layer is a layer and comprises external wall, internal wall(s) and infill.

 

Also I am not sure "which are already finished" is referring to.

 

I am not sure why you would want to print a model with 0 top layers; is that intentional ?

[MatejEU 1]

Hi, thank you for stopping by

16 minutes ago, yellowshark said:

You say "I have an issue with the infill structure being added on the top internal layers, which are already finished". There is no such thing as an internal layer; a layer is a layer and comprises external wall, internal wall(s) and infill.

If we can agree that once can have, e.g. a model of two independent cubes, where one is contained in another. The outside one would have its top/bottom layers as would one contained inside of it. So to describe layers of an object that is contained inside of another object, I would say internal top/bottom layers or the top/bottom layers of the smaller object located inside of the outer object. In my first post, I'm reflecting on a hinge that that is not coupled to the outer object, i.e. it is independent of it. It has to have its internal top/bottom layers. It would be probably helpful that you look at the actual model: https://www.thingiverse.com/thing:2595224

 

27 minutes ago, yellowshark said:

Also I am not sure "which are already finished" is referring to.

This should be clear from my previous explanation.

 

28 minutes ago, yellowshark said:

I am not sure why you would want to print a model with 0 top layers; is that intentional ?

I definitely don't want to do that  How did you get that impression? 

 

So, to make a summary:
1) Select top thickness of 0.8 / 0.2[layer height] (mm) = 4 layers.

2) On the outer object it does it properly.

3) On the internal object it will make three complete (filled) top layers/surfaces and add this strange thing that has outer/inner walls and the infill (not like a support).
4) From that top internal layer there is a certain clearance, lets say of 0.6mm until it gets covered by outer object's layers

5) Reduce top thickness from 0.8mm to 0.6mm = 3 layers.

6) On the internal object it will make three complete (filled) top layers/surfaces and it won't add anything else, as it has finished those three top layers.

7) From that top internal layer clearance is maintained, it didn't raise/lower the layers.

 

I'm quite sure there is a bug in the code, somewhere in the conditional checks 

Does Cura have a Facebook support group? This is very slow with all the moderation of user comments.

[gr5 2,167]

14 minutes ago, MatejEU said:

Does Cura have a Facebook support group? This is very slow with all the moderation of user comments.

This forum is new and we are still trying to figure out the moderation stuff although so far your first comment was approved within I think an hour and definitely the one above within 10 mintues.  More the problem might be that the cura software people are taking the weekend off (most likely).

 

After you have made 10 posts moderators shouldn't have to approve you.  Feel free to make 7 more posts of one word each and I'll approve them all so you don't need to wait in the future.

[gr5 2,167]

Okay so your issue is very unclear but I'm pretty sure I got it now.  I downloaded the STL you are talking about.  What you want to do is check the feature in Cura "ignore small z gaps".  This will fix the issue you are talking about at the expense of taking 5% longer to slice.  I think this should be checked by default but it isn't.

 

Basically there must be some kind of pre-processor that looks at the slices and sees that in e.g. 5 layers a top surface is coming up and settings say we should start solid infill now - but it doesn't realize that before then there is also a bottom surface coming up.  Or vice-versa.  Anyway check this box to fix your issue.

[MatejEU 1]

26 minutes ago, gr5 said:

What you want to do is check the feature in Cura "ignore small z gaps".  This will fix the issue you are talking about at the expense of taking 5% longer to slice.  I think this should be checked by default but it isn't.

This works! That feature is checked by default in version that I'm using and it has caused this issue for me. I've unchecked it now and it behaves as expected, at least from my point of view  From the tool tip info, it seems that I'm actually saving ~5% of computation time and getting what I want by unchecking it 

Thank you gr5 

[MatejEU 1]

If anyone is wondering what is the difference in the final print, here is an example. On the left side is what I expected to get and on the right is what I got.

For me this is a significant improvement