When is a CNC Program more than a G code program ?

... when it's a set-up sheet as well.

Most people are familiar with the ability of most CNC controls to include COMMENTS in the CNC G code program itself. Comments are designated in a variety of ways from :

1. ( THIS IS A FANUC AND OKUMA COMMENT ) ... any text inside (  ) is considered a comment.
2. ! THIS IS AN ACRAMATIC COMMENT ... any text following the ! is considered a comment.
3. ; THIS IS A FAGOR COMMENT ... any text following the ; is considered a comment.
4. and on and on we could go.

Comments can be a real help when they include operator messages ... such as :

M00 ( TURN PART AROUND )
or
M00 ! CHECK DIMENSION A

... but comments can go well beyond operator messages and can turn your G code program into a complete set-up doc as well that includes tool information, part zero locations and even stock descriptions.

Most people will create either a paper or digital tool sheet / list and / or set-up sheet / list that is stored and re-called when the corresponding G code program is going to be run again. The set-up personnel refer to these docs to set the machine up ... loading required tools and setting height offsets and work offsets. Works great ... no problems. But is there a better alternative? The answer is a "could be" yes. By storing this information directly in the G code program using the COMMENT capability of your CNC control. For example ... something like this :

O1234
( PART #1234 )
( PROVEN PROGRAM : 7/2/2014 )
( PROGRAMMER : JM )

( PART LOCATED IN VISE USING JAWS JW-1234 )
( STOP SET-UP IS RIGHT SIDE - WORKPIECE STOP AGAINST FLANGE )
( X/Y PART ZERO IS LOWER LEFT CORNER )
( Z0 = TOP FINISH SURFACE )

( T1 / H1 = #3 CENTER DRILL )
( T2 / H22  = 1/2 DRILL )
( T3 / H3 = .500 CARBIDE END MILL )

So what is the advantage of keeping this info directly in the G code program using the COMMENTS capability of the CNC control?

1. Harder to misplace ... if you're going to run the program, you need the program ... and all the set-up info is right there stored right inside the G code program.
2. Complete info is there for all to see at any time ... no rummaging for loose paperwork or docs.
3. Any edits or changes can be made directly in the program ... when the running program is saved after execution ... all the current set-up info is changed and saved as well including all updated data.

We often get asked ... "Won't this slow down my program execution speed?" The truth is that it will ... but it will also be so minimal that usually the cost savings of having comments and all the convenience that comes with it far outweigh any reduction in program execution time. Rummaging around for lost documentation or re-creating lost documentation would be the real money waster.

Just a little something to think about if you haven't considered COMMENTS already in your CNC programming. We touched on only a few points here ... but we're sure you can find many more benefits depending on the capabilities or lack thereof pertaining to your particular CNC programming operation. The fact is that expanding the use of COMMENTS in your CNC programming could be a real time and money saving alternative to digital or paper documentation.

Until next time ... Happy Chip Making !!

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