On Wed, 16 Nov 2011 14:12:12 -0800, "PrecisionmachinisT"
wrote:


wrote in message
.. .
On Wed, 16 Nov 2011 11:10:22 -0800, "PrecisionmachinisT"
wrote:


wrote in message
...
On Tue, 15 Nov 2011 17:16:48 -0800, "PrecisionmachinisT"
wrote:


wrote in message
om...
I posted a while back that I might be buying a Fadal mill and running
it from a phase converter. Well, I'm buying it. I'll write the check
tomorrow. It's a model VMC-15 and has rigid tapping so I guess I'll
need that parameter changing info. Also, just what is the advantage of
rigid tapping over tapping heads?
Thanks,
Eric

The main advantage of having rigid tapping is that it allows you to use
standard drilling collets and chucks instead of having to buy a bunch of
additional specialty tooling that is only useful for tapping.

So all the compression/tension tap holders and collets I'm also buying
are not neded? I can just hold the taps in ER collets for example?


You would still do well to buy at least one rigid or floating chuck and a
handful of adapters to use wherever it is advantageous to drive from the
square tang--but mostly they are only needed for larger diameters...say
1/2
or so and above and in tough materials like stainless where high torque
requirments might otherwise allow the tap to slip.

That said, you'll usually also be able to better control thread tolerance
limits with tap adapters because they typically allow for the tap to
wiggle
a slight amount on the radial axis and so it tends to center itself
instead
of being horsed into the material, producing a loose hole...

--something to consider for instance if you are doing a aircraft work in
aluminum where 3B fits are the norm.

Thanks everyone for the answers about tapping. Since the machines come
with tap adapters already I'll continue to use them when I can but if
a job comes up with more tap sizes than I have adapters I'll run the
smaller taps in regular holders. Especially since I almost always try
to put class 3 threads in or on whatever I'm machining. Since this
will be my first mill with a toolchanger I need to learn as much as
possible about optimizing tooling.


Sounds like a plan.

A pretty good method is to have some larger collet chucks say for instance
in the DA180 and/ or TG100 series and then buy spare collets in the 3/4 and
1 in sizes for them so that if the need arises where you need to run a whole
bunch of small drills etc, you can put straight shank extension chucks in
them that your smaller collets will fit into.

The logic behind this is because oftentimes where you have several different
sized holes in a part and they are all over say...5/8 or so in diameter,
you might just as well to drill undersize and interpolate with an endmill
rather than to try and stock your crib with a myriad of the large drill
sizes in attempt to cover every possible contingency..

--Yes it might take a bit longer to interpolate but oftentimes it's more
expedient than to purchase drills if doing short run work and also
considering that since the VMC 15 has no mechanical reduction, it's torque
is seriously lacking at the lower rpm ranges and so you can run into
problems with spindle stalling especially when running large HSS drills in
alloy steels.

The torque problem is one I deal with running parts on the lathe. I
have one lathe with no gear reduction but a 15 hp spindle. I have
another with a 10 hp spindle but it has a gearbox that goes all the
way down below 200 rpm. So it gets used for big stuff or when using
big drills on SS. It's nice that the Fadal interpolates round holes.
This is something I'll need to get used to thinking about.
Eric