Lines on Surface (not isocurves)

What are these lines on my surface and how to hide them for CNC?
Isocurves are turned off.

Is the selected object a single surface? Or a polysurface. If isocurves are off, the remaining lines are the joins between surfaces. MergeAllFaces should do the trick if they are planar.

Thanks dharman. Job done on the polysurface but not on this valid surface:

surface

ID: 53409c61-15fd-444a-b4c6-afb95d10b6e5 (214867)
Object name: (not named)
Layer name: Default
Render Material:
source = from layer
index = -1

Geometry:
Valid surface.
surface.
NURBS Surface"U": degree =3 CV count = 4 (0 <= U <= 219.353)
“V”: degree =3 CV count = 101 (0 <= V <= 11768.1)
Edge Tally:
4 boundary edges
Edge Tolerances: all 0
Vertex Tolerances: all 0
Render mesh: 1 mesh 297 vertices 196 polygons
Created with fast meshing parameters.
Analysis mesh: none present

Gunnel Chamfer.3dm (73.0 KB)

Surface uploaded.
Yes, I could simply separate the perimeter lines but with hundreds of files to cut this could be tedious.

Hi -

Can you post that surface?

If these are flat surfaces and you are only interested in the outside border, you could just extract these as curves.
-wim