odd holes in sliced part

[stang6t8coupe]

Hi,

i am new to simplify3d and 3d printing in general, so far i love it.

I am still learning, now i have some odd behaviour on a sliced part. I seems to be connectec somehow to some holes for screws, simplify3d doesn#t follow the outline correctly. I was not able to find any settings that corrected it.

before slicing

after slicing:

Could anybody help me with this?

Thanks
Adrian

[CompoundCarl]

I'm betting it's because your STL file has a bunch of self-intersecting surfaces and isn't an actual valid 3D solid. If you cross section the part right where that issue is happening, so you see extra internal surfaces that shouldn't be there?

Post the STL file if you want someone else to verify what's wrong

[jimc]

Either what carl said or your coasting value is high and or a big neg restart value has been entered. Cant tell or help without you posting a factory file