Hi Michael,

Thanks for the explanation, that makes perfect sense to me.
I had a feeling that it was something simple that I was missing within the process.

With this kind of Sweep I'll make a point of setting up my profiles on the left hand side, in line with each other & a bit more away from the rail.

regards Colin

Hi Colin, I'm glad that makes sense now.

One subtle part is whether "auto-place" mode kicks in or not.

The way it is controlled is if your profile curves intersect with the bounding box around the rail curve (like one example is if they are touching it, but it is actually controlled by whether it is inside the box around it), then auto-place mode will be _off_. That means that MoI will not move or rotate your profiles, they will be taken directly from their current positions and then swept along the rail curve.

Otherwise, if your curves are outside of the box around the rail curve, auto-place mode will be activated, and MoI will move and rotate your curves to be perpendicular to the rail before sweeping them.

So that's what placing the profiles off to the side does - it just makes it easier to make sure that auto-place mode is enabled.

- Michael