Re: Getting started - MaxNC comments

--- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:

> I have not experience with MaxNC so this is all 3rd hand.

Unfortunately all

> the comments I have heard from users of the software are less than

positive.


At the recent NAMES show I took a MaxNC
machine to demonstrate stepper motor drivers.
The machine was chosen because a friend had
one and had been disappointed with the
performance of the control system and we hoped
to improve on it.

Previous comments had alerted me to the phase
drive and marginal power of the base model.
My plan was to connect the prototypes of the
upcoming PMDX-150 drivers. This immediately
required a change in software to drive
a step and direction system. After playing
with the MaxNC software we decided to not
try to use the step and direction version of
the MaxNC software, but rather use DAK's
TurboCNC. The primary driver of this decision
was the inability to get the MaxNC software
to jog in a predictable fashion. It seemed to
attempt to "run" for however long you held
the key down instead of moving a precise
increment.

The next quandary was that the stepper motors
supplied with the unit were 24 volt unipolar
units. The high voltage would have made it
difficult to drive the motors fast, but that
turned out to be irrelevant because the motors
were internally wired as unipolar ONLY with
5 wires coming out. The windings could not
be isolated without surgery to the motors.

Next we decided to fit a set of more robust
motors that I had previously acquired. It
was very simple to change motors, but this
is because MaxNC used a very unsophisticated
setup. The motors were secured to the machine
by two screws through their regular mounting
holes plus two screws used as clamps to hold
the flange to the machine. All of these were
to one side of the shaft. The other side of
the motor was unsupported.

The lead screws were connected to the motors
with a rigid coupling and setscrews. This is
bad enough by itself, but turns out to be
required because there are NO bearings of
any kind on the leadscrews. They are supported
only by the feed nuts and the stepper motor
shaft. This means that the motor bearings
act as thrust bearings for the lead screw.
While this may be sufficient on such a small
machine, it did not inspire confidence.

After saying so much about what I did not
like about the MaxNC, I should say what I
did like. The table, ways, and column were
well made and functioned well. They were
large enough to give the impression that
they could handle larger work that a Sherline.
The overall design was simple and easy to
modify if one is so inclined. Also, it should
be noted that this was a MaxNC model 10 from a
couple of years ago. Some of the characteristics
that I described may have changed. MaxNC does
offer larger and fancier machines, but I have
not seen any of them.

Cheers,
Steve Stallings
http://www.pmdx.com