As a way of getting more used to MoI's tools I have started a small project, which is to make a simple, cartoon-like model of a 1950s racing car (deeply unoriginal I know). Having taken a look through the docs it seemed like a sweep with a scaling rail was the way to go. I decided to split the car into two halves, upper and lower. Accordingly I made two profiles, one for each half, a pair of rails used for both halves and a pair of scaling rails, one each for upper and lower halves. MoI swept both without any problems. The two halves look OK and (as far as I can tell) they are touching.

Unsurprisingly there are some nasty sharp edges and an ugly lip at the front that I need to get rid of. Unfortunately I cannot seem to fillet the two halves to achieve a smooth blend on which I can then perform a boolean union. I select fillet, then the two halves, radius (anywhere from 0.1 to 10 - doesn't seem to make a difference) but there's no obvious effect. Are sweeps not filletable? Should I union the two halves first? Any pointers much appreciated!

Cheers
Dan