Strange surface behavior (when blenderCam tries to find the surface)

Hi all,

i constructed a body for blenderCAM -> milling. However, the surface is not respected (the tool follows not the surface but drops down to final Z-height).
I think this is not cam specific, but some error in my geometry, which I can not find. Any ideas?

Details:
This is a body (bezierCurve.002 in the blend file) for which it works as expected:


You see the toolpath travelling on Z=0 (top) and then going down to the surface and following the surface.

For another body modeled using the same sequence of steps ‘c1FullCurveBeforeArray.001’ (explained below) the probelmatic behavior occurs:
Screenshot_curvedBody3
Here you can see that the cutter drops down to final Z, not following the surface - as if it would not be there.

How are the bodies modeled:

  • I make a bezierCurve (it actually is a cross section of a surfboard and I need to match certain locations exactly, therefore bezier and not nurbs).
  • convert it to a mesh
  • remove duplicate vertices
  • make a face
  • duplicate and shift it
  • select both and bridge edge loops
  • recalculate outside (I checked normals in both cases everything looks fine)

As a result I have the two bodies.
I can find no difference and it’s not clear to me why in one case everything works as expected, and in the second not.

Any ideas how to debug this?

supboard1_43CAM4debug.blend (601.5 KB)

the blend file