Normals issue - simple wheel rim

Please can someone offer some help to resolve this pesky normals issue.

I have tried about 20 tests this evening, about 19 of them on my original wheel rim mesh, all failed with the "Your model has inverted normals in it" error.

I don't know how this can be, as the model appears fine in 3ds max.

I decided to go back to the drawing board and produce a simple version.

I uploaded this simplified model (56mm diameter, 23.5mm height), and still got the error.

There is nothing fancy in this mesh, so I am now officially flummoxed.

I'm loving Shapeways (got a couple of items from other modelers earlier this week), but getting over these hurdles is proving almost insurmountable.

Can anyone please shed some light as to what might be causing this?

I have attached a DAE file in mm units and can supply other formats if requested.

pimpmybricks,

Can you upload an stl.
I Can't open the .dae. An iges or step is also ok most of the times.
I would like to try to fix the file.

greetings AO

I have attached an STL file for your inspection and would appreciate any clues as to what causes this and how I can avoid the normals error in future.

Thank you for your assistance on this.

Hi Pimpmybricks,

The object is very simple and should not cause problems if you model clean. I saw alot of shells, that cause non manifold problems. Did you use boleans?
The model contains alot of meshes that are not unified.
I tried to fix it there are 2 shells left. If its not printable its because of that.

Greetings AO