Hi Michael - see how this works - it is soemwhat tested in real life, not a lot.
Save the rhp file and in Windows Explorer, Unblock the file, then drag and drop it onto Rhino.
the commands are
DogBone
TBone
Input is a closed planar curve - you tell the tool whether the curve is hole or not, so it knows which corners to hit, , and set the radius.
The DepthFactor is a slight overshoot, .05 radius, I think, by default, to make sure there is clearance.
Bones.rhp (35 KB)
-Pascal