In article XddUc.265104$a24.75997@attbi_s03,
Steve Koschmann wrote:
Good question... and one that really has no "right" answer. Since you are
working with soft brass, alumimum and plastics, the Chinese ones will work
just fine for the first set of cuts.
The real difference between cheap Chinese and more expensive American
tooling tends to be the quality of the steel used, followed by the
tolerances (a chinese 1/4" end mill might be .245 to .255). You can easily
Agreed.
[ ... ]
As for the Titanium coating, it helps initially -- maybe--, but not for
long. The coating is supposed to act as a lubricate, thereby making the cut
easier and smoother. Maybe it is also supposed to provide a "harder"
cutting edge, such that you can mill or drill harder materials, but I have
never found any difference between regular HSS and Ti coated steel. If y
ou need to lubricate, than use a real lubricate likeTapMagic or kerosene for
Al...
(To be blunt, I have often suspected that the Ti coating is often used to
just "cover up" cheap steel, and make the bits or end mills look pretty.
Novices too often fall for what looks good orwhat is hyped to the nth
degree must be good... and this goes back to my first comment.. Chinese
steel is often suspect...)
Agreed here -- though TiN coatings (not really Ti) do offer
improvements on good quality tool steels when cutting the kind of
materials where the coatings are worthwhile.
You also can not resharpen drill bits or end mills with the coating as the
grinding immediately wears the coating off -- as does normal wear and tear.
Actually, in drills and mills the place where the coating offers
benefits is the inside of the flute, where it lubricates the sliding of
the chips, and helps to avoid a built-up edge (and also reduces the
transfer of heat to the tool itself. Under normal sharpening, this area
is *not* removed, and also does not wear as fast as the ends of the
flutes where the sharpening does its work.
I have never paid the money for TI, if I was going to pay extra, I always
would go for carbide or Cobalt tooling.
If I were going to pay extra, I would really like TiN (or one of
the other specialized coatings) over *good* carbide or Cobalt steels.
Obviously, TiN over junk steel still gives you junk tools.
[ ... ]
FWIW, I am a big advocate of carbide for cutting any type of steel and I
tend to use HSS/cobalt for everything else... ALL my lathe tooling now is
carbide and the mill uses anything that works g!
That is what matters, after all.
Now, I start answering the original article, which has not yet
made it to my news server, so I have to work from the quoted copy here.
collection. I don't do large quantities of anything; I generally (but not
always?) work in soft materials like aluminum, brass, and plastic; and my
"mill" is actually a mill/drill. So this is light duty work; but at the
same time, I want the pieces I make to come out nicely, and I know that
with
a dull or imprecise tool there's just no way to cut a straight line or get
a
smooth finish.
Note that some plastics are rather abrasive, so carbides will
give you longer life in those. But here you really *don't* want a
coating, because that rounds the edges, losing you significant amounts
of sharpness, which most plastics really demand.
One option I've considered is starting with a set of cheapo end mills in
order to get a lot of sizes, and then gradually replacing the ones that I
find myself using most often with better quality. But am I shooting
myself
in the foot to consider cheap end mills at all?
Try medium cheap. I've got a set of TiN coated double-end ones,
both two-flute and four-flute in a convenient range of sizes up to 1/2"
(bought on sale from MSC), which work well in spite of being from China.
They are nice to have on hand -- but for sizes which I use most
frequently, I want to have high quality ones.
And, a subsidiary question: does TiN make any difference? E.g., I'm
looking
in the Grizzly catalog at all the cheapo plain HSS and TiN-coated HSS
sets,
It can increase the life of a tool -- *if* it is on good steel.
But beware that inexpensive tools with TiN coatings are mostly coated to
*look* more expensive.
And in plastics, where sharp is important, your really *don't*
want TiN coatings (or any of the others) as they round off the edges a
bit.
Good Luck,
DoN.
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