Object not manifold ... why ?

I designed a one-layer thick grid to print as first layer of my Star-trek Chess board.
It will be followed by another color design that has this grid subtracted from.

However, despite the fact I made it from simple primitives, its ends up being not manifold.

Can someone explain ? One layer is manifold I presume if only solid shapes are used....

This happens on the MAC.
When I upload the code to Openscad.net, it renders without a problem ....

Thomas

Edited 1 time(s). Last edit at 03/08/2014 03:42PM by Replace.

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

If you subtract cylinders of the exact same height, or if two solids are touching at a "zero thickness" interface, OpenSCAD doesn't handle it well. This file is edited so that the subtracted cylinder is longer, and the spokes are moved inward so they overlap both the inner and outer rings. File attached.

Hi Matt,

you're my hero.
So basically, I should overlap structures a bit.
I will keep that in mind !

Thanks for editing, you made my evening:-)

Thomas

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

This old blog post explains it well: OpenSCAD Tip: Manifold Space and Time

It is also pretty good advice for many CAD programs.

Yes, this is clear now.
Thanks. I fixed all my problems in the object by tiny replacements.

Thomas

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)