First cut in aluminium. Disaster.

[Dangle_kt]

I had the same problem, chip weld isnt really about speeds and feeds from what I can tell (well it might be if they are way out I suppose).

Anyway - chip clearance is critical, as is the right endmill - to begin with try 3 flute HSS endmill of a decent size, and use compressed air directed at the endmill at all times.

I used a 3 flute endmill, but it was TiLAN coated, and thats no good for alu! OOPS! Lesson learned, either plane carbide or HSS for Alu.