Sweep1: Clean surface through under-sized outside curves?

I am trying to use Rhino to model what will happen when I run a router bit along the perimeter of a shape. The side profile of the bit is a simple 3mm radius. The challenge is that there are some instances where the outline of the shape (rail) will be curving back on itself with a radius of less than 3 mm. Sweep1 doesn’t deal well with the overlap. The attached image shows what happens. In this exercise, I am trying to do a 3mm radius going around a 2mm outside corner:
This is a simplified scenario. More generally, the rail is going to be an organic interpolated curve.

  1. Is Sweep1 the right command to be using?
  2. Are there setting within Sweep1 that will help it deal more gracefully with the overlap ‘flaps’ ?
  3. If I need to do some coding to accomplish this, then what approach would be effective?

Hi Keith- I guess the router bit can overlap itself, so to speak, in its path, and you’ll never know but the surface makes it obvious. I don’t see, off hand, how to get this right consistently, you’d need to sort out building each corner.


Yup, I just wanted to make sure that this complication wasn’t already addressed by simply using a different command (i.e. revolve rail) or sweep1 command option.