Structure line display in Make2D

Sorry to bother. Get some question on make 2d of an extruded object.
Maybe due to the control points on the extruded curve. The objects shows with lots werid structure line. However while I try make2D of them they shown in the make2D result as well. How can I not including these lines in make2D result?

Make 2D result:

Extruded object in wireframe mode:Object%20in%20wireframe%20mode

Thank you

My theory here is that those lines appear because your original curve “arcs” are not really arcs, but segmented polylines. So what you are seeing in Make2D are the the joined surface edges. You can check this by exploding the original curve that made the extruded object or the extrusion itself - if it splits into a bunch of tiny surfaces, that’s it.

In that case, best just to make the original curves correctly with true arcs and then re-extrude.

Thank you. Yea. You are right. The arcs are composisted of tiny segments. Is there a way to make these “Fake arcs” into real arc with any function?
Simplify curve doesn’t seems work. Should I redraw them manually, Since there are lots of them it is kinda horrible to redraw each of them…

Yeah, I’m afraid that’s the only real way, sorry. If they are 90° arcs and aligned with the XY axis, then try with Arc>Start>End>Direction with Ortho on, it goes pretty fast. Otherwise Arc Start>End>Point on arc and snap to the appropriate points…