Ridges in 3D profiles = hair loss and lots sandpaper

[Shinobiwan]

Could it be the material itself and not the cutting process, in other words is it lamination showing through?

I get the same pattern on both high density polyurethane block, mdf and valchromat so I don't think its the material.

[dsc]

What I'm about to type might be stupid, coming from a person with no CNC experience, but isn't this caused by the movement being done in two steps, rather than simultaneously? so instead of moving say 1/4 step up and 1/4 step left at the same time to get an angled movement, it first does 1/4 step up and later on (scan later?) a 1/4 step left, which results in a step made in the material.

Regards,
dsc.

[Jonathan]

Since the ridges seem so consistent, they could be part of the original CAD model. For instance if you imported the model into the CAM program as an STL, then that approximates the surface with triangles. If the resolution of the file is insufficient, then you will see the flat surfaces left by the straight line approximations to a curve. Look very carefully at the model imported into the CAM program to see if you can discern any pattern.
Similarly it could be the G-code being generated at too low a resolution, so using lines a few mm long, instead of arcs and lines which are too short to see. It's hard to tell from the code you posted. Can you post a bit from the main profile section, i.e. somewhere in the middle?

[m_c]

Check Jonathan's suggestion.

If you look at the code, there are jumps in the Z.
It starts of with relatively small steps around 0.05 rising to about 0.2, however there are 3 distinct jumps.
Line 110-115 Z moves 0.597, 225-230 it moves 1 and 340-345 it moves 1.965. I know those big moves also correspond with big steps in X and Y, but it does mean the code is a bit inconsistent, and may cause havoc with the projectory planner.