Unless I have missed something simple, VIACad does not allow arrays of holes. In particular, in modeling a simple flange, I want to create a polar array of counterbored holes. An array is produced, but it replicates the entire flange, rather than just the hole. So, instead of a flange with six holes, I end up with six coincident flanges, each with one hole.

I thought that perhaps the hole is not an object that can be manipulated like a solid, however I find that if I select the hole feature in the history tree I can move it, so why can't the Polar Array function produce an array of holes?

The alternate is to design a slug, array it and then subtract the slugs from the flange, rather tedious at best. Simple holes and countersunk holes are not quite as tedious--an array of circles, use the Cutout tool and for countersinks, chamfer the resulting holes. Still though, a lot of work when there are many holes to do.

A bit of a kludge, but intersecting the arrayed flanges leaves you with all of the holes in one flange.

Perhaps ViaCAD doesnt have the tool, but in Shark this is easy. Use the Patterm Polar tool.

http://screencast.com/t/ZDNmYmIxYWQt

I think that this is what you are looking for.

Create the plug of the shape of the holes you want, counter bore or counter sunk for example. Array the plug. Use the subtract solid tool and select the flange then window select all the plugs. It's actually quite easy.
Chuck