Hi Jamie,
Yes, miniature end mills are available. I’ve been known to use small
end mills on wax, but very rarely on metal, at least by hand.
Drawback #1 is that they tend to be expensive. My mental price list
tells me that I’d expect to pay between $20 and $80 each for good
ones. Banging around on the web, I did find this guy:
http://www.ganoksin.com/gnkurl/1qn
who has mini mills for $7 each, in a variety of sizes. So it could
be that my head is out of date, or this guy’s wildly cheap. Dunno
which.
Drawback #2 is that they aren’t intended for hand use. They’re
brittle, and they are very, very agressive in comparison to a
standard burr.
If you use them in a miniature drill press, they will indeed give
you exactly the flat bottomed hole you’re looking for. The support of
the drill press keeps them from digging in. If you try to freehand
them in a flex-shaft, they’ll likely dig in and snap almost
instantly. (I’d try a very light cut, and the highest speed your
machine can provide, to keep the flutes from digging in.) (and
ABSOLUTELY shalt thou wear safety glasses! It’s not a question of
odds: there will be high speed fragments.)
I’m at sixes and sevens about whether to get 2 flute mills or 4. 2
flutes clear soft material (like wax & silver) better, but are more
likely to grab and snap when used by hand. 4 flute mills won’t grab
quite as easily, but it’s easier to jam them full of crap, and
break them that way. The more I think about it, the more I think 4
flute mills are probably safer if you can find them.
The other fun thing is the chips: depending on the end mill, and how
you use it, the chips coming out can frequently look like tiny
little silver needles. Not only do they look like microscopic
needles, they act like invisible little needles, jamming themselves
into your skin in places where you can’t find them without a
microscope. But you can sure feel them…
FWIW,
Brian