the engraving was a bit of a one off, but point taken

Quote Originally Posted by magicniner View Post
The reasonably fine "engraved" features will tend to fill up with anything that might help cover rough surfaces.
The example you asked about has no fine surface detail, most likely for this reason.

You could cut the part leaving material for a fine finish path with a ball nose cutter on the detail and seal it with cyanoacrylate before the finishing cut,

- Nick