Risto:
So far, the answers to your question about generating 5-axis g-code
appear to sidestep the core difficulty ---
In general, knowing the 3D geometry of a part tells you next to nothing
about making the part. If the part is complex enough to require 5-axis
machining, then it is likely to be complex enough to require a true CAM
(computer-aided machining) program to generate usable g-code no matter
what exchange file format you use to extract the part definition from
your CAD program. These CAM programs depend heavily on knowing the
available machining operations and the kinds of features that result
from them.
Most of us get away with trivial g-code generators because we are
cutting trivial (from a programming perspective) 2-1/2D parts that can
be aligned with the Cartesian axes of our machines and our cutting tool
can only go up and down.
To give a simple example of my concern, suppose I want to create a
TinkerToy hub, basically a cylindrical pillbox with a thru-hole along
its principal axis and eight radial blind holes equally spaced around
the circumference of the cylinder. An apprentice machinist ought to be
able to whip one of these out by inspection of a shop drawing, even if
all he or she has at hand is a drill press, a vise, and a basic
knowledge of layout. I could emulate the same process on a manual 4- or
5-axis milling machine (3 Cartesian axes + a rotary table + possibly a
rotary head) but to automate the process I have to be able to tell my
g-code generator what motions and operations are available on my
machine, which are useful for creating the features of this part, and
which g-code cycles are needed to execute them.
Previously on this list, we have mentioned CAD/CAM program suites such
as Synergy (www.webersys.com) [MS Windows and Linux] and Alibre
Design/CAM (www.alibre.com) [MS Windows only] because they provide many
good capabilities and because their full capabilities can be evaluated
freely. To my limited knowledge, neither provides for 5-axis machining
operations but your mileage may vary. A quick Google search turned up
FeatureCAM (www.featurecam.com). It looks very, very good. It also looks
very expensive (typical for industrial software), and apparently it uses
a dongle-based license key system (gack! I swore years ago that I'd
never touch a dongle again).
Sorry if I'm bloviating, but with the wide readership of this list, you
never know who understands the limitations and strengths of various
software strategies being discussed.
Good luck.
Regards,
Kent
PS - By sheer coincidence, only last week I was at our local Borders
Bookstore thumbing through a newly available book entitled Secrets of
5-Axis Machining by Karlo Apro and published by Industrial Press,
October 2008 (ISBN13: 9780831133757, ISBN: 0831133759, BINC: 9570839).
It was too expensive, about $55, for me to buy on a whim, but it
contains very handsome illustrations of 5-axis processes and comes with
a CD containing avi files, high quality illustrations, and sample
parts, to quote from Borders website.
--
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