[patrickrd]

G-Code is one of my favorite programming languages! I learned it from a manual that came with the CNC machine that I used, but I found the following web site which looks like a good overview:

http://www.linuxcnc.org/handbook/gcode/g-code.html

Good luck! By the way, it is rather uncommon to write G-Code by hand. Lots of CAD programs are available with manufacturing packages as well, and these manufacturing packages can generate G-Code for your CAD drawing automatically. You simply have to tell it which surfaces you want to machine with what tools, how your stock is mounted, specify some parameters (such as feedrates, spindle speeds, and tool properties), and it will generate the G-Code automatically for you. In any case, it is still pretty important to know the main G-Code commands if you are going to operate a CNC machine.

- Patrick

And here is some of the G-Code used to machine an omni-wheel. This is G-Code that I generated automatically from I-DEAS:

(OPERATION CATEGORY & TYPE: Milling Volume Clear)
M05
(TOOL IDENTIFIER: End Mill 01/16)
(POST TOOL ID: 0)
(TOOL DESCRIPTION: 1/16 End Mill (2 flute))
(TOOL STATION NUMBER: 11)
(Start Region 1 -- Depth: 0.304375)
T11 M06
M01
G56 H11 D01 Z.72
M08
S8000. M03
G00 X1.7454 Y1.1004
Z.42
G01 Z.3044 F7.5
X1.7385 Y1.099
X1.7527 Y1.0322
G03 X1.757 Y1.0271 I.0069 J.0015
G01 X1.7594 Y1.025
X1.7601 Y1.0238
X1.7621 Y1.0264
X1.7653 Y1.0294
G03 X1.7665 Y1.0351 I-.0057 J.0043
G01 X1.7523 Y1.1019
X1.7454 Y1.1004
Z.4044
G00 Z.72

Can you guess which part of the omniwheel this is for??? Interestingly, CNC machines used to read programs off of a roll of tape (holes were punched out in rows and columns to encode the commands). The above program, if I had pasted the whole thing, would require a roll of tape over one mile long in distance!!