C of G Issues

[jason_charnley19]

I am modelling a sphere with cutouts that I require to be perfectly balanced.  When I begin the basic sphere is fine - Center of gravity zero and Inertial properties for Ixy, Ixz & Iyz correct - all zero.

Then I add to cutouts and all is fine -

Then I put a bore through and still good.

Then I add a radius to the corners of the cutouts and the Center of gravity and Ixy, Ixz & Iyz are incorrect - they should still be zero.

This also happens if I add other features to the model such as cutouts in the bore -

As all these features are symetrical I would expect the center of gravity Ixy, Ixz & Iyz to stay at zero.

Can you explain why I am getting an error? 

[swalton]

You may get better answers on the main Inventor forum.  I've asked the mods to move this post.

Do you have a sample part file you can add?  It may help others troubleshot the issue.

[jason_charnley19]

Hi Please find attached test file

[catBUN5M]

There is no attachment?

But from looking at the pictures I would think that this is an Inventor rounding issue during calculation of COG or something. Anyway, the deviation is so small 0,000007mm that in practice it is 0.