Hi Chris,
I have just been trying to get a rough pass, I have never tried a 6mm carbide end mill as I don't have many and I'm sure the ones I have are only for wood, but I will order some and try, could you please tell me how to find you on YouTube, as I would like see your channel, I must have watched hours of cutting aluminium on YouTube and you can hear some of there end mills screaming. then you find one that it looks like it was cutting butter with a hot knife and that's where I want to be but am having a hard job finding the right information.
I have watched a Dennis martens cutting 6040 aluminium but there is no information about how he is doing it feed and speed plunge rate etc.