Slicing very detailed model has issues with external perimeter
I have a very detailed model (created from orthographic data) - see attachment
Slicing it with Prusa Slicer causes an issue: It seems as if the external perimeter (see screenshot - orange layers) does not fully cover all the model's surface, so the internal infill (red) and the perimeter (yellow) remain exposed.
The less detailed I choose the print settings (e.g. 0.25mm DRAFT), the more area of the model is not covered correctly (see screenshot).
Best Answer by Neophyl:
The slice is exactly as it should be. There is nothing 'incorrect' in what you have pictured. Several misconceptions as to how things are sliced in your initial post.
First of all the red is not internal infill, its TOP fill. Research terms such as stair stepping. Your areas with the external perimeter actually on top of other external perimeters are steeper slopes. The angle means that when sliced into discrete layers the edge of a layer sits close to the layer below it. With shallower angles the edge of a layer sits further away from the edge of the previous layer. Naturally this means its sits on top of the yellow normal perimeters. As it gets shallower it has to move the edges of a layer further back, at that point its shallow enough to be 'flat' so it has to create a top surface, as such it sits the edge of the next layer on that top fill.
As Diem points out you can mitigate this effect to a limited extent by using a lower layer height as the slices are thinner. Inversely choosing a thicker layer height exaggerates the effect. This is perfectly normal and is how 'slicing' works 3d printing.
As Kaszpir says if you want higher resolution then you should choose a printing method that allows that level of detail such as a resin printer rather than FDM. Even there you are still subject to this effect, it will just be a lot less noticeable.
Your maximum vertical resolution is your layer height... You effectively get contour lines at each layer.
Cheerio,
RE: Slicing very detailed model has issues with external perimeter
You could try to rotate the model to be on the side ( but then other may be problematic).
Generally FDM are having limited use in here due to the resolution they can print with.
If you are looking for such detailed prints, then maybe you should look for different printer, for example resin?
See my GitHub and printables.com for some 3d stuff that you may like.
RE: Slicing very detailed model has issues with external perimeter
The slice is exactly as it should be. There is nothing 'incorrect' in what you have pictured. Several misconceptions as to how things are sliced in your initial post.
First of all the red is not internal infill, its TOP fill. Research terms such as stair stepping. Your areas with the external perimeter actually on top of other external perimeters are steeper slopes. The angle means that when sliced into discrete layers the edge of a layer sits close to the layer below it. With shallower angles the edge of a layer sits further away from the edge of the previous layer. Naturally this means its sits on top of the yellow normal perimeters. As it gets shallower it has to move the edges of a layer further back, at that point its shallow enough to be 'flat' so it has to create a top surface, as such it sits the edge of the next layer on that top fill.
As Diem points out you can mitigate this effect to a limited extent by using a lower layer height as the slices are thinner. Inversely choosing a thicker layer height exaggerates the effect. This is perfectly normal and is how 'slicing' works 3d printing.
As Kaszpir says if you want higher resolution then you should choose a printing method that allows that level of detail such as a resin printer rather than FDM. Even there you are still subject to this effect, it will just be a lot less noticeable.