Mesh Normals Mixed Up, Some in others out. Looking for a fix!!

This question has probably been asked thousands of times, however when I try to research it here, I get more on Normal Maps than Mesh Normals.

Anyway, the situation. I have a blend model file that I have downloaded that was textured using nodes in cycles. I’m taking that model back to Blender Render and applying the diffuse texture created (Not a problem).

However when I display the Mesh Normals on the 15000 faces, I’ve got mesh normals pointed inwards and other normals pointed outwards. Doing a Recalculate on the normals only fix some, but there are still thousands pointed inward and I need them pointed out. Going to the select Menu and using the Select Inward faces does not light any of the faces up so I can flip them.

The question. Without going through and selecting groups of individual faces, is there any way of identifying the inward faces so I can flip them in one or two shots?

As a side, once I get these flipped, how do I assigned them as pointing correctly so that if I do a recalc Normals they don’t flip inwards again?

EDIT: I guess I should point out that this model is already rigged and weight painted and I don’t want to disturb that.

Thanks Gang

Before recalculating normals ensure to remove any duplicate vertices and any non manifold faces. These will both prevent recalculating normals working correctly

Hmmm, Thanks for the quick response Richard. The problem with that is that I may need some of these to complete the model and prevent ripped mesh or kill the weight painting (maybe??, still looking into what Non-manifold mesh actually is. Didn’t even know it existed until I started researching this problem). I haven’t looked at the model that closely yet. But I will try this and see what I get.

Excellent, Thanks Richard. I selected non-Manifold and split them off into their own separate object (just to retain them), then deleted the doubles.

I didn’t find any holes in the resulting mesh (even after hiding the new objects created doing the split). Recalculate seems to have performed it’s duty perfectly.

Now to check the aftermath in the rigging and weight painting… lol.