issues with a imperfect circle in HFSS and export for fabrication

When we make two intersecting circular sheets (or cylinders) with 'number of segments' as '0' for making perfect circles (or cylinders) and subtract one from other, with 'clone tool object before operation' checked, we can see gaps between those two. Thus when such geometries exported as .stp for fabrication, error in geometry comes. To overcome this error, we need to redesign the structure in mechanical drawing software like 'CATIA'. because for fabrication in CNC machines, .stp file can be directly provided as input.
Can anybody help in quantifying the imperfection made by HFSS? Or suggest any alternate to avoid the redesigning the structure in mechanical drawing softwares for fabrication?
I have observed this problem when I tried to make excitation with SMA connector to a circular waveguide wall. Thanks

From my experience, fabrication driver software always requires discrete values for curves (i.e. a number of straight segments). If this is the case, you can set the 'number of segments' properties to some finite number (e.g. I typically use 720). If you do this for all your cylinders, there shouldn't be any gaps remaining.

Using a number of segments in cylindrical model, HFSS takes lots of memory. Thus a single model using for optimization and simulation may not be possible. Or may be alternate so that simulation model can be used for fabrication. Thanks