CNC Blog October Archive

CNC Machines and G Code

By Wilbur Corncob at 10/31/07 12:33

If you are interested in the world of numerical control and CNC machines, you surely must have heard about the word G-code. For those of you who are not familiar with this term let me assure you that this is not rocket science of some thing of a classified nature.

Basically G-code is used to refer to various types of code which is used to program and control the motion of CNC machines. Originally it referred to the code developed by the Electronics Industry Alliance as early as 1960. But of late although the name is still in popular use, currently it does not refer to a particular or specific language but there are different variation of the this code with each specific to some vendor or manufacturer.

This is so because there is very little interoperability due to the vast nature of machine tool configurations which are available currently. An attempt was made to standardise this code when in the year 1980 a language was named by the name of RS274D which was a sort of final revision of the G-code.

It also refers to various commands which are given as a part of the programming language meant to control the movements of the machine tool which are controlled by motors who get their signals from computers. To give a few examples of such G-codes just look at the following.

G00 -- Rapid Positioning G01 -- Linear Interpolation

Computer Numerical Control software which actually translates the code into machine tool movements

After the completion of computer aided design and computer aided manufacturing, the next step consists of the Computer Numerical Control software which actually translates the code into machine tool movements which then carries out the real function of manufacturing finished products or parts out of the raw material supplied to the machine.

Hence this software controls the 2 and 3 dimensional cuts which are given to the raw material by the various tools with precision and accuracy. There are various popular softwares available for computerized numerical control as well such as FlashCut and so forth.

Such software have the ability to accept standard G-code and M-code files and execute the commands hidden inside them which translates to tool motion of the machine. The tools are moved by motors and servos which are governed by the electronic pulses generated as a result of execution of the CNC software which converts the machine code instructions in the G or M code format into electrical and electronic impulses which in turn drive the motors required for the purpose of cut manipulation.

The main advantage of such softwares is that they give a visual and real time control over the machine tools which makes it easy for the engineer or the technician to observe the results for themselves.

The path from CAD to CNC Machining

If you remember our last blog you might remember that we were discussing about CNC software which basically consisted of three types of software. Now don't jump to the conclusion that after CAD its CNC machining straight away.

There is an intermediate step as well which comes under the purview of CAM or Computer Aided Manufacturing. It is an intermediate step since it tends to correlate the gap between the geometry as defined by the CAD software and the machine code which CNC machines need to run and produce the desired affects.

CAM is used in the middle to convert the geometric shape of the stored parts in the software into machine code which is understood by the CNC machines. Therefore CAM software provides directions to the machine by creating what is known popularly as the G-code which directs the tools etc of the machine so that it converts part geometry into tool directing code.

There are various professional software packages available for computer aided manufacturing and some of these include MasterCam, SurfCam, Vector and so forth. In actual practice most of the popular CAM programs integrate directly with CAD software so that there is no need of duplicate entry of geometry of the latter into the former.

Mach 3 Drivers

Some of the Mach 3 Features include up to 6 axis CNC controller. It converts a windows PC into a CNC controller.

You can get a visual G-Code display, import JPG, BMP, DXF and HPGL files. Mach 3 also generates the G-Code.

The Mach 3 can control

• Engravers
• Gear cutting
• Lasers
• Lathes
• Mills
• Plasma
• Routers
• and More

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