Different site now so I have network that works.
Here are some screen shots. (note that the tool parameters- RPM, travel rate, etc are defaults. They need to be set for a particular job, material, and machine)
General setup for the machining operations
First op is an 3Dadaptive, leaving 0.2mm for finishing and fine stepdown of 0.2mm
Second op is scallop to level the flat areas and get into the corners at the base. This isn’t going to get everything due to the undercut required at some places. The undercut leads to some other finishing issues later, as well. To get a good final job, I should eliminate the undercut, either by projecting the profile to the surface or building out the bottom with a fillet. I chose not to bother here.
Note that this was done as rest machining, and 0 adjustment (to not ignore minor profile issues from the previous ops) I also selected the surfaces to touch.
Third op is with the larger ball end. It should only touch the rope feature. Again, set up using rest machining. Stepover is 1/8 of the tool diameter to minimize scalloping on the surface with convex curvature.
This is actually a pretty nice look (IMHO) as the finish looks a lot like the stranding of a rope. A little tuning or pencil work on the concave sections between the strands would tighten it right up.
The pecks at the meet to the flat surface are an artifact of the undercut at the meet. There are a number of ways to eliminate this (revise the model, force a small clearance by setting the bottom plane for the operation to be 0.001mm above the flat surface, etc) but, in this case, I don’t even know if it will be visible in the final product. The simulation tends to highlight these things.
The last op is another of scallop (The morphed spiral would also work here, but tries to maintain a roughly circumferential path, while the scallop op doesn’t worry about that. The less regular toolpath tends to hide a lot of small defects) The small tool gets a lot more detail and cleans up the grooves between the strands, but does have trouble getting all of the way to the bottom in some places due to the small tool needing to be short (the shaft and/or toolholder will collide, even at this scale. the 0.8mm ball end mill has about 2mm of flutes and 3mm total length to the shoulder)
note the stepover is 1/4 of the tool diameter. 1/8 would give a minimally better result on the convex, as the convex looks nearly like a plane to the tool this small. The extra time isn’t worth it. Also note the shaft and holder clearance. This provides another AVOID condition. The tool won’t rub or try to collide with stock or finished surface, and the tool holder (model your tool holder. Really. MODEL YOUR TOOL HOLDER. This is as important as modelling the tool) will be kept clear as well. I am not worried about the tool holder for this operation, so I didn’t enable it. These options do slow down toolpath generation.
The final sim looks quite good, except for the previously mentioned issues.
The primary thing would be to eliminate the undercut. If I cut the part, I will probably revise the model, as well as adjust the bottom height for the cuts with the ball end tools rather than using AVOID.