Hi jimbowley
my spindle on my machine only goes up to 8000, the cut depth is 0.8mm and it cuts the phenolic board pretty good, I did cut some plastic with it and it melted the plastic but I found if a used a little bit of wd40 it was fine I haven't used it on delrin. The end mill I mostly use is 1.5mm but have used 3mm for removing material. I am sure other members will give you better advice on what to try as I am really only a beginner.