Endmills

[pugs]

The gummy aluminum is probably Chinese stuff if it is marked as 6061-T6. It is just softer and sticks to tools, leaves bad finish. I specify US made aluminum when I order material after several bad experiences with the cheap stuff.

In alum I don't like 4 flute endmill, stick with 3 or 2 as that gives you more chip clearance for the aggressive cuts you can take. High helix mills designed for aluminum work really well. Lately I've been using OSG blizzard brand 3 flute, have used alot of CGS 2000 series 2 flute in the past. They aren't the cheapest but they seem to run longer and faster for me which means cheaper per part.

For taps I only use form taps in alum, so much nicer.

If you plug up a mill with aluminum, or lolipop it as I call it, get yourself some Lye drain cleaner (Red Devil) and a small container. put the endmill in some water into the container and sprinkle some lye in. It will start getting hot and bubbling while it eats away at the aluminum. really bad plugs may not completely dissolve away but usually good enough to be able to pop it off carefully. Do in well ventilated area as the vapors coming off are hydrogen. It will turn the endmill black but it leaves the edges sharp yet. Usually let it sit till it stops bubbling which can be 15 mins or more depending on how much lye you put in.