Weirdness slicing a glorified tube

Hi Folks,
posting here and repetier sections.

Repetier-host 1.6.2 + slic3r 1.2.9

I'm attempting to print a microscope adaptor - essentially a tube with a flange and some fancy bits at the top.

Downloaded the part from thingyverse, prints just fine, but dimensions are off.

slice, adjust, make whole and go again...

except now the slicing does not work.... either the tube is filled in, or the support and part meld into each other with unexpected parting lines at the flange...

much weirdness.

same settings for slic3r on both parts.

things I've tried.

inverting the normals.

repair in netfabb basic

OBJ and STL

recalculating the normals. reversing the spiral, redoing from scratch with different approaches...


TBH, I suspect it's not a Slic3r thing... but I've run out of ideas to try...

image attached shows the modified stl on the left and the original on the right - now it's clear what's going on, even if I can't work out why that is... slic3r isn't happy with the modified version, and is missing a lot of the triangles -

note most of the missing aren't modified triangles...

I'll try a few things, see if it helps.

Looks like the modified model is non-manifold or something like that. The scaling probably caused a rounding error or something so that parts no longer quite touch.

What's the thingiverse link? What scale factors were you applying?

What does Slic3r show in its preview and 2D views?

Was there a photo of a printed part at Thingiverse or did you just discover one of the many designs that get posted without ever being printed by the designer?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]