I have had a bit of time this evening to play in the workshop. I re-wrote the cut files for the fin mould. This time I used an 8mm cheap dremel cutter, as I only had 6mm and 10mm in the good stuff. I played around with the settings in Vectric 3D and ended up with a range of 26 minutes to 9.5 hours to cut the mould!!
I decided to use the same cutter for the rough cuts as well as the finish cuts and saved them as a single, combined file. Running it through Mach3 simulation gave a total of 11 hours 16 minutes to complete.
I used 1mm pass depth and 7% stepover. I thought I would at least be able to see how the cuts looked before I stopped for the night. What I didn't plan on was the cutter only lasting 15 minutes before becoming blunt. Just goes to show, we need to use good quality cutters for this type of work.
Anyway, despite this I was happy with the quality of the cutting - whilst it lasted. See attached photo for the quality.
I will have to have a play with your mould file in SW to allow me to cut the dowel holes as a seperate entity.