I've tried alum W/O and success. Try a carbide ball end endmill the same size as the tap drill running at full speed while peck drilling. It will destroy the endmill so consider the cost of the cutting tool V making the part again.
The best cutting compound I've ever used for tapping in aluminum is pork lard. If that is not to your liking try solid vegetable oil. In the States Crisco is the leading brand. Penetrating oil such as WD40 is also excellent.
The best cutting compound I've ever used for tapping in aluminum is pork lard. If that is not to your liking try solid vegetable oil. In the States Crisco is the leading brand. Penetrating oil such as WD40 is also excellent.