Hobby CNC milling aluminum

Milling through an aluminum square tube with 3mm endmill.
CNC machine is a "colinbus profiler", spindle is a Kress 1050 fme-1.
Endmill is a 2 teeth "fishtail", not sure about parameters, but should be around Vc=60m/min, Fz 0,02mm/tooth/rev, depth 0,1mm.
Pretty slow and coward, but the machine is not extremely stiff and I cannot cool the mill (parts of machine are wood and nothing is liquid-tight). This setup gives almost no vibrations and the surface finish is astonishing: you can see mirroring in the machined slot when machining the oval hole.