Re: What does everybody use...

Don Hughes wrote:

> I would like to know briefly what the majority of members here have for
> their setups. Please take me from the PC(including all hardware and
> software) all the way to the cutting head.

I hace built my own 3-axis CNC vertical mill, based on an old
Bridgeport round-ram manual mill. I retrofitted a J head to it before
the conversion - a big improvement.

The computer is a 100 MHz Pentium classic, with 32 MB of memory.
I run Red Hat Linux, with the real time patches installed. The CNC
control software is EMC, from the National Institute of Standards and
Technology. See this url for details:
http://www.isd.cme.nist.gov/projects/emc/emc.html

Note that some of the web page info is old, it works better and has
more features than it did when these pages were written.

I used the axis drives out of a scrapped Excellon CNC circuit board
drilling machine. That was a GE Mark Century tape-NC control,
with precision ball screws, resolvers and shunt-wound DC servo
motors. I replaced the resolvers with 1000 line shaft encoders, and
get a resolution of .00005" (50 uInch) on the X and Y axes. I was
able to finagle an excess .1" lead ballscrew for the Z axis, and so I
get .000025" resolution on Z. The knee is manual right now.

I made my own DC servo amps. I started with a reference design
for a PWM audio amp from Harris, but their 'does everything' chip
which was rated for 80 Volts, couldn't handle more than about 55 Volts.
So, I had to use a bunch of chips to perform those functions, but
I now have a real fine servo amp. I don't have a need for 800 IPM
rapid feeds, I think 120 IPM is plenty for a small machine. I have the
X and Y amps set for about 5-6 Amps, maximum, and 69 Volts.
The Z axis has a lower voltage motor, so I have that axis set for
about 10 Amps, max.

You can see various aspects of this system at :
http://www.artsci.wustl.edu/~jmelson/machining.html
Some of the pictures and info refer to my Allen-Bradley CNC
control, which I used until NIST's EMC was up to speed.

Jon