Re: Gcode standards (Was: easy to learn use cad/cam cnc software?)

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Chuck Rice <Chuck@W...> wrote:

> At 1:11 PM -0800 11/1/04, Chris DeHut wrote:

If you have written a G-code program over 30-40 lines, you are
wasting time that could be better spent designing parts, planning
process and making chips. DXF converters are free and cad-cam
programs are very inexpensive.

G-code is supposed to be man-readable. It started out as all hand
coded.

> #4708=[#4708+[#4706*0.8379]]

Use of varables and expression evaluation is not standard g-code.
This is the EMC developer's isolated interpretation of a machine
controller, selecting the features he wanted. Fanuc Macro language
(an expensive optional add-on) uses the cryptic # symbol for
variables, but in many versions does not permit mixed expression
evaluation and motion commands on the same line. It was a hardware
issue when all the controller logic circuits were hand wired,
discrete components and simple logic chips.

Most controllers use subroutines and repeat statements, with absolute
and incremental modes to make hand written code more legible, thus
eliminating a lot of the need for cryptic code. EMC does not support
subroutines or repeat commands.

A decent cad-cam program will permit you to produce many more parts
per hour spent developing programs, reduce your mistakes, and permit
much more efficient changes to your part designs. It will also
permit you to connect your drawing and design skills directly to the
CNC controller, without restricting your programming to the speed at
which you type.

For example, Engraving Text is a very simple process with a CAD
system, but a gut wrenching task when manually programming.

3D surfaces can easily be processed by nearly any hobby class
controller. I doubt 1 in 10,000 would even try to manually program
these parts. Pocketing, the process of clear cutting a closed shape
to a defined depth, is a very tedious manual process. With a cad-cam
program, a perfect toolpath and the associated g-code can be created
in a few seconds.

In addition to the commands that others have mentioned as
standardized, also learn (for milling)

G90 Absolute mode
G91 Incremental mode
G41, G42, G40 cutter comp control

G81 and G83 are drilling cycles that are very similar between
controllers, with an ocassional swapping of letters for the various
parameters. All the other drill cycles will be more
machine/controller manufacturer dependent.

Fred Smith - IMService - Vote Early and Often

hobby and group discounts are at:
http://www.cadcamcadcam.com/hobby