weird solid layer toolpaths on middle layers

[skinnyp]

Hello. I would like to discuss an issue of solid layers generated in random places. Thanks to @Muggs I have screenshots with a perfect example.

Bulbasaur model has 174 printable layers.

Important gcode parameters:
Top layers: 2
Bottom layers: 2
Outline perimeters: 3
Infill: 20%

Visible screens are from layers 171 and 168.
You can see the weird zig-zag tool path, circled on red.
Color of these path is marked as solid layers.

It is weird for me as these layers are far from 2 top layers, and even further from 2 bottom layers. Furthermore they are not covering whole area limited by outer and inner perimeters.

[CompoundCarl]

Because that's exactly what the slicing settings for that part told it to do. For example, if you specify that you always want the part to have at least 3 layers of solid plastic on the top of the part, then when you have a very shallow surface (such as near the top of that model), the software will need to add additional plastic to ensure that you always have 3 solid layers on the top.

For example, imagine the roof of a house, but instead of being at a 45 degree angle, it was at a 1 degree angle (almost completely horizontal). If you didn't add extra layers of plastic, then you would have all kinds of holes in the roof and you also wouldn't be obeying the setting of always having a certain number of solid layers on the top of the part.

Anyways, it sounds like you haven't used the software yourself yet, so I won't bother explaining too much more. There's plenty of ways to change these settings if you want different behavior, or even use different settings for different regions of the part to customize it further.