Hi,

I've tested what you suggested, and here's the result.
'Angle' value is 12, and 'Weld vertices along axes' is ON:



Keeping 'Angle' at 12, but turning 'Weld vertices along axes' OFF:



When I increase the resolution and n-gons size ('Angle' is 8), this is
what happens. 'Weld vertices along axes' is OFF:



The same but 'Weld vertices along axes' is ON now:




And here's a problem I've found editing this object in MoI. As you can
see in the images, I've just selected that edge, and then apply 'Fillet'.
And that's what happens to the surface:



I've attached the IGES by the way, so you can test it (housing_shf_60_l.rar).


Thanks!!

Jacobo.