Hi DrBombs, it's normal to get those edges, every segment in your starting curve will extrude out to a face and the edges that you show there are where the faces are joined to each other.

To get rid of them would mean controlling the source curves to only have one segment instead of being multiple segments. If your curves are smooth you can use the Rebuild command (type the Tab key then type Rebuild and push enter) to fit a single segment across a set of smoothly touching pieces or actually a kind of sneaky trick is you can export the curve to SAT format and then re-import it. That will have a side effect of fusing smooth segments together.

re:
> Keep getting 'Calculation Failed', HELP!

It's hard to help just looking at screenshots, please post the .3dm model file that you're having trouble with and then it will be possible to help you.

- Michael