Unprintable .stl files  

Unprintable .stl files

I have several different files from one source author downloaded via Thingiverse.

I cannot get most of them to print without serious corruption errors on my i3 Mk3.

Slic3rPE indicates many errors corrected on loading. (Over 3000 in one case, which became the test print used below)

There are some minor triangular planes visually evident AFTER this correction within the box like structure. It compiles .gcode without protest, but when printed there are loads of faults, far more than visible in the Slicer, with holes where print should be and solid where holes should be (in some cases the right shape but inverted from correct) . Looks like lots of missing and/or transposed points in the file. This is consistent, same appearance each time.

Cura shows less errors so less is corrected, the file looks better, and complies without protest. When printed on the Mk3 it again came out as above, though less seriously affected.

HOWEVER, Repetier Host (using its supplied Cura slicer implant) indicates on a raw uncorrected file that it is non-manifold, but when this in-program repair correction is run, the file(s) subsequentially print well on my USB connected Fabrikator II Mini.

Why is Prusa's system unable to correct and process what the much cheaper Fab II system can easily manage?