Milling out a plastic shell
Yes, a block of wood to put inside it is a must. One thing you will quickly find out using a mill is that anything that
is not very firmly held down will either:
a) Mill horribly, with tears and cuts all over it, or just plain mill crooked -- if you are lucky
b) Vault across the room, possible in pieces, possibly into your face or eye if you are really unlucky
I am by no means a milling "expert". I have just felt my way along. I use an older version of that Micro Mark mill.
Mine has an MT3 spindle, not the R8. The R8 is better because there are a lot more accessories available that fit
an R8 taper and they are less expensive than things that fit the MT3 (Morse Taper 3).
As for choices of end mills:
I use 2-flute or 4-flute. The 4-flute make a slightly smoother finish, but they do not clear chips as well as the 2.
But frankly, for 100% of the milling I do, which mean model train stuff in brass, aluminum, mild steel, and plastic,
I haven't seen it make one bit of difference on chip clearing, so I tend to get 4-flute. We in the little train world
are just not milling anything tough enough that it matters. At least, that's my opinion.
I use HSS (high speed steel) mills whenever possible. Carbide are harder and sharper, but they are more brittle.
And again, for the soft stuff we tend to be milling, I'd rather have the HSS bits that don't break as easily.
When you get down to very small end mills (like 3/64", 1/32", or smaller, they are only available in carbide,
so you just have to get what you can.
For doing your plastic shells, you may find that putting a Dremel sanding drum in the mill will work great - maybe even better
than the cutter and with less stress on the shell. In that application, you are not milling for precision. You just need to
"take off some plastic" to make room for your decoder.
Other things you will almost surely want:
1. milling vise
2. clamp/hold-down set
3. a good 3-jaw chuck (because lots of times, it will be quite fine to use this for drilling, and you can even mill
with a simple chuck for all the light work we do)
4. parallels (precision, thin steel plates for supporting your work
5. end mills - probably want to start with some 1/16", 1/8", and 1/4". Get standard length (not stub or "long").
That ought to be enough to get you started. There is so much to this, you will need to experiment for a while to discover what you really like and need.
Other things I really like having.
6. Dial indicator - very useful for making sure the mill itself is set up true and square, and for measuring your
work when you are doing precise milling
And you may eventually want a good collet chuck that fits the machine you get (R8, or whatever your spindle taper is)
and a set of collets. These will hold the end mills much more precisely than a 3-jaw chuck.
I have a collet set, but I am not entirely happy with mine. While it holds the mills great, it's a little less
true than the chuck... but that's a weird situation. Normally, you should find that a collet chuck and collets will
get you better cuts than a chuck.
Alternatively, you can just get endmill holders. These are tapered sleeves designed to fit into your R8 (or other) spindle
directly, and hold the end mill. You have to get a holder for each diameter endmill shank you buy, so you will probably
need endmill holders for 1/16, 1/8, and 1/4 at least, to start.
Hmmm what else?
OH! DEFINITELY check out the little machine shop!
Here's a page of milling tool packages they sell, so you can easily get a nice assortment of stuff you will need
in one package, no matter where you end up buying your mill.
http://littlemachineshop.com/products/product_focus.php?Focus=Tooling+Packages&Source=GoogleStartKits&device=c&keyword=tooling%20small%20lathe&utm_medium=referral&gclid=CIzVkaDcwc8CFRdahgodUS8CqAThe also sell mills. Generally, these are the same China-made mills that everybody sells (Micromark, Grizzly, and others),
but LMS will have it set up and adjusted for you, and they also put nice upgrades on their mills,
Here's the X2 they sell with an R8 spindle, and a 3-jaw chuck included.
http://littlemachineshop.com/products/product_view.php?ProductID=4962&category=1387807683This has a solid column (doesn't tilt side-to-side... because almost nobody ever needs to do that,
and it makes the mill more rigid and less needful of adjustment), and the air-spring vertical column support
(much better than a torsion spring, which tends to let the head drop a little unexpectedly sometimes).
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Whew.... that's my $.02.
Good luck.
