Re: Future CNC man

Shawn:

I'm not sure the posts I've seen answered you questions so let me try
to expand a little. Although I'm pretty new to this also.

Autocad is a CAD package which generates drawings consisting of lines,
arcs, etc. This is the first step to a part. One can use other
modelers but I'm sure Autocad will work. The drawing is saved from the
CAD package in some format, like *.dxf or *.dwg.

A CAM (computer aided manufacturing) package (software) then reads this
drawing/modeling file. If the CAM package imports or reads *.dxf or
*.dwg you should be able to get the drawing in but as with any import it
may take some futzing. In the CAM package the drawing in interpreted
from lines, arcs, etc. into a tool path. A tool path is a description
of how the CNC machine moves its spindle/table to cut the part. Here
additional information like the order of cuts, speed used, multiple
cuts, etc are used with the drawing to define the tool path. The
'moves' are saved to another file. This output is usually in G-Code
which is a text file describing the moves. Vector is an example of a
CAM package.

The G-Code file is read into a machine control program. The G-Code
commands are in standard format but there are differences. But, again
with some futzing, the CAM program will output a text G-Code file the
controller can use. The machine controller interprets the G-Code and
outputs signals (for example to the parallel port) telling the CNC
hardware how to move. EMC is an example of a control program.

From there it's up to the hardware, motor driver and motors, but you
asked of software.

Windows or linux can be used for CAD and CAM. However, Windows and
linux don't have the timing control needed for a machine control
program. Thus most control programs still use MS-DOS. There is a patch
which allows linux to do precise real time control however. This real
time linux is used by EMC and works very well.

So the software parts of CNC are CAD, CAM and machine control. These
are sometimes combined, particularly CAD/CAM but can be thought of as
separate steps if not separate programs. Likewise, it is possible to
write a text G-Code file and skip the CAD/CAM steps, for simple
programs. But in general these are the chunks of software used.

I hope this is of some help. :-)

On 21 Sep, shawnusa@... wrote:
> I plan in th near future to setup a CNC for a 3-n-1 system. I have
> not worked all the details out on the hardware side, but I was
> wanting to know what is needed from the software side to get the end
> results on the CNC machine. I'm a user of Autocad and wish to stay
> with it. What is involved in taking a Autocad file and turning it
> into a working part. I see lots of refrences to EMC for linux. Would
> files move from the NT Autocad enviroment to the Linux and is there
> some sort of file conversion? Anyway I'm trying to visualize what's
> involved on the software side of things. LIke I said though I would
> like to use my Autocad files.
>

--
Hugh Currin
Klamath Falls, OR