why dont my layers make sense?

I used tinkercad to cut a model in half.
loaded into both matter controll and cura.
the 3d rendering looks perfect. but when I scroll through the layers, it dosnet make sense. starts in one area then another area , then across the two area, almost at random.
I made sure the model was aligned with the bed and was carfulll to rotate 90degrees while working in tinkercad.

any idea what is happening and how to fix?

 

If you're running Windows 10 you might want to try doing the cut with 3D Builder, found it generates good output (and can fix broken meshes efficiently too).

 

Check the advanced settings to see if "randomize layer start points" is checked (or an option that has similar wording).

It's perfectly fine to have the machine doing that, and it won't end always end a layer in the same place it starts one because of the path it has to take to lay down the infil after tracing perimeters, but you can minimize that by changing it from "randomize layer start points to "Optimize layer start points".

It'll still happen because there's no way to 100% eliminate it, but it is possible to minimize it.

The downside to doing that is that you're going to have to do a lot of experimenting to perfect the end-of-layer retraction settings so you don't have a single line/seam going up most of the print where layers start/end.