On Thu, 3 Feb 2005 15:58:18 -0800, skuke wrote:

On 3 Feb 2005 09:42:59 -0800, wrote:

Good info, thanks all.

Yaa, I meant *twice* the machining time of the 50k machines

I would be fine with a used machine but don't want something that will
require a lot of maintenance costs of course.

Does the ALLIANT CNC VERTICAL MILL W/ANILAM CRUSADER M EQUIPPED WITH:
9" X 42" fit the bill as far as ability to hold this tolerance and also
the run time?

I might be pursuaded to go with an enclosed machining center for a
little more money since it may work better down the road. What are my
price options for the smaller units and also for the less expensive
(I'm assuming import) units? Used prices but not for worn out stuff.
What are the top places to watch for these as they become available?

Thanks again guys.

Joe



I've programmed and run several Alliant w/ Anilam Crusader (circa 1985-90)
as well as well as later Fadals (1993+) and Bridgeport EZ Track (1998). Did
R&D, as well a 3 axis Aluminum molds. Neither of the knee mills could hold
+/-.001 without a lot of work and very careful setups. You needed to
consider ALL aspects of the problem if you really wanted to hold your
required tolerances. The Fadal could hold .001" on 3 axis w/o *too* much
trouble.

I'm sure you could find a used 3 axis knee mill in the $7k range, but that
machine would probably have been "ridden hard and put away wet." It won't
hold the tolerance you request (without a lot of extra work, and then only
just maybe).

Spend more money and you'll be happier in the long run. JMHO. Also, please
consider if you *really* need +/-.001" Are you making matched dies?
...duh, I guess not if they're aluminum. But my point is that .001" is
pretty tight to hold day in, day out with any kind of efficient speed.
I have a Wells Index CNC knee mill. The mill itself weighs 6000 lbs.
So it's bigger than your typical bridgeport type knee mill which weigh
about a ton. The control on the mill failed a few years ago and I
bought a new control from AJAX. Even though about 20 years old and
plenty used the machine is quite accurate. So holding .0005" location
when boring holes is a breeze. I can get closer by changing the
program to compensate for position error because the machine repeats
to .0002". So an older machine can be checked for error in both
positioning, flatness, and squareness and if good enough then it might
fill the bill. I bought my Index mill mainly for complex shapes, not
for production. My next mill will be enclosed, the Index is not. Being
enclosed will keep the chips and coolant in the machine and allow
higher speeds and feeds without throwing chips and coolant all over
the place.
ERS