[ee_t]

Might want to check runout at the tool.

[universalfab]

Your doing this thing on a mini mill? Thats 1 problem, how deep of cut are you taking? 6061 is some of the easiest if not easiest to cut material that there is and leaves a beautiful smooth shiny finish whenever I cut it. Your long tool is also a big dangerous problem. I also recommend you use a 2 flute cutter, if your using a puny little mill that isn't rigid your going to get not so good results. Also lower your spindle speed and feed when using large tools, I don't care what your cad/cam output tells you to run it, you need to run it low. There is nothing wrong at all with using HSS cutter your using. But your going to get tool chadder if not run correctly from the length of the tool. Why are you using a long endmill? Any one who tells you to raise your spindle speed while using a larger cutter doesn't know what they are talking about, you always use low spindle speed with large cutters. I guarantee you turn your feeds and speeds up with a big cutter and its in steel your going to destroy your endmill almost immediately in a puff of smoke. What exactly is the size of your mill? I think a good portion of your problem is that, and how is it mounted? Is it just setting on a table or what? Using a longer tool holder like darebee said is also a good one. 2 flutes thats what you need, aluminum doesn't break up like steels, it has longer chips, which is why you need 2 flute because it gets the chips out better. Another thing is your chips, that will also leave you with a pile of garbage for a part if you don't get them gone. Good luck thats plenty of info to get your job done just right there alone.

[universalfab]

Wow... Not even a thank you, hmm... Seems like to me there's not many machinists on this website. Some programmers who know what there doing but actual machinists who know tools, materials, feeds/speeds, and exc. exc. are quite rare in this community. Not to mention the welders on here who think they know how to weld and repair welds are quite a joke. I've spoke to a few people but the majority don't know their heads from the a$$'s. Not trying to make any enemies, but if you don't know what your doing don't say it. You could get somebody really hurt or worse off dead. Hopefully this guy is'nt in the hospital getting sewn back together after he listened Dare Bee's awful 8500RPM exploding endmill trick. Knowing how to diddle around on your computer and listen to your programs feeds/speeds doesn't make you a machinist.