Re: What do we want?

Message: 16
Date: Mon, 18 Oct 1999 14:25:14 -0400
From: Bertho Boman <boman@...>
Subject: What do we want?

I see many comments and requests for CAD being integrated with the "CNC" or
"CAM". Maybe my definitions are not well defined
and I guess it depends on goals and how we work.

I know there are very high end systems where everything is integrated and
machining centers are tied together with the design
systems (car manufacturing for example) but I do not think that is our
goal, at least it is not mine.

I see several levels of system requirements but would like comments and
suggested typical programs for each.

PHASE 1: When I design a new product, I spend days and often weeks to put
the system together so that all the individual
hardware and subsections fit and work together. After that, I create
drawings and specifications of the different components
and normally send the drawings and DXF file out to get prototypes made.
If the parts can reasonably by made manually, I make
my own prototypes. I am in the process of converting my mill to CNC.

This point seems to me to be a crucial dividing line. My work as an
engineer is over and I put on my machining hat and go and
get dirty.

[It's nice to be able to make and try out your own prototypes, saving some
expense and delay. For machine part assemblies, the programs based on
parasolid geometry are especially handy, since the various parts of the
assembly are related to one another- make a change in the parameters of one
and the adjacent parts will adjust (assuming you've set it up correctly.)
The program I saw demonstrated that did this was SolidEdge
<www.solid-edge.com>, but other programs have these capabilities as well,
like Pro-Engineer <www.ptc.com> SolidWorks <www.solidworks.com> and
VisiModel <www.vero-software.com>. If people out there know of other
parametric solid-based programs, perhaps we could work up a FAQ page
comparing their features and prices.]

PHASE 2: Actually, once I am in the shop, I would work in the shop office
first and create "the machine control file". I like
to be able to load the "data" from the previous design program or from a
customers data file. Hopefully, the customer will have
it as some data file, DXF, or what not. Presumably, at this point I will
need a program to generate G-codes from the data file
together with my manual interaction for tool selection and desired tool
path. I envision this program as an intermediate step,
a converter, from the engineering world to the machining world and the
output would be G-codes although I have seen references
on the list to other unfamiliar systems. The G-codes can be saved and just
reused for future production. It would be important
that the converter program can show tool path and machine operation to
catch blunders. Even better, hopefully, it can also show
clamps and fixtures.

[For converting 3d models made in a CAD program to G-code useful for
machining, there are now several programs in the lower price ranges, some
of which I've used and others of which I've only heard. At the bottom of
the price range ($795) is BobCad <www.bobcad.com>, which has been around
for a while- it's now in version 17. There's a new contender from Larken
Automation in Canada <www.storm.ca/~larken/surfer.htm> called "3d Surfer"
which is sold for about $1000 US. And then there's DeskProto 2.0
<www.deskproto.com> from the Netherlands, which I have tried and found
fairly easy to use (I sell it for $1450). After that you get into more
expensive packages like VisualMill <www.mecsoft.com/VisualMill.html> which
are capable of the remachining passes necessary for producing molds and
machine parts. Surfcam <www.surfwareeast.com> and Mastercam
<www.mastercam.com/index.html> are other popular CAD/CAM programs in the
higher price range. I'd like to see some knowledgeable commentary on the
advantages and disadvantages of these (and other) programs from people who
have used them- this would be a useful part of our FAQ.]

This is to me the second major dividing line. Now the data is ready for
production manufacturing (hopefully) and it gets to the
flying chips part.

PHASE 3: From the shop office the G-codes would be sent to the machine on
the floor. There the G-codes and tools and DRO
functions would be displayed and the part would be machined under "CNC".

There are other desired software features that would be nice, for example,
reverse G-code to DXF and some type of quicky
"manual" CNC for very simple operations on the floor.

[Many machines offer this functionality- if equipped with a probe, they can
function as digitizers, but the resulting data often needs to be massaged
considerably to be useful. One can also do some machining using the "jog"
function of a CNC machine, and some machines allow one to record these
moves and repeat them. Many machines also come with simple "canned" cycles
for cutting arcs, circles, pockets, and other geometric shapes.]

Andrew Werby


Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com