Missing Layers in Cura Only when Models are Merged

[geojenks 1]

Hello,

 

I have made a model that will be printed in 2 materials, so I have 2 STLs that can be grouped. If I leaved them unmerged and slice the model in Cura, then they each independently look as if they will print ok. If I group them first and then slice, the smaller part of the model (for printhead 2) seperates really weirdly - parts of it are missing every other layer, parts of it look as if they will print ok (see pictures). The X-ray looks fine, and I've printed similar models before that have been ok. Why is Cura slicing my model so weirdly, and how can I force it just to do what it was doing before I merged the model, but for the merged model?

 

Any help appreciated, thanks

 

-- It errors (code -200) every time I try to upload the photos so I will post this, and then try to post photos in a reply

[geojenks 1]

No I can't upload images. Here are some external links to see them:

 

https://ibb.co/xX3RRfB
https://ibb.co/RStywt8
https://ibb.co/D1JN4SR

 

Essentially the problematic part of the STL is 7 solid bodies, 2 of them look perfectly fine on the preview tab of Cura, the other 5 are all missing every other layer, so one layer is present, but nothing is printed immediatley above, but the layer 2 above is fine. This means that when I print it, there is too much of a gap and the print doesn't come out ok.

This only happens after I group the print with the other part, before grouping, if I slice the model then it looks as if it will print every layer just fine

[geojenks 1]

I have solved my problem. For anyone who may come across something similar:

 

In the design of my 3D object, some of the solid bodies had duplicated in place, so that 2 identical objects sat within each other. I would have thought that this wouldn't be such a problem, but going to my 3D object and deleting the duplicates solved my issue. I think this is an unusual symptom with a seemingly unrelated cause that I can't quite make sense of. Hopefully someone may find this post useful in the future

[GregValiant 1,410]

Thanks for getting back.  I don't know how you brought the models into Cura but usually in the lower left corner of Cura is a list of the pieces in the scene (the Object List).  The problem may have been catchable there as there should have been more parts than you would have expected.