Hi, I do quite a lot of routing with 3.2 and 6.3mm HDF/MDF. I mainly use 2mm PCB endmills and run the spindle at 2400+ rpm and a feed of about 2M/min. I do sometimes (if in a hurry) run at 3or4m/min, but worry a bit about tool breakage. at 2M/min the tools last for ages.