by Doug Rinehart
Every programmer-operator has to make changes to a program from time to time “on the fly” during-a parts run. It is quite easy to lose your train of thought during such changes, which opens the door to making mistakes – especially if you don’t have a hard copy of the program. I recommend using a technique developed while changing parameters: document the current setting before making changes. With this technique, you’re throwing yourself a kind of “life-line” that gives you the ability to change the program back to its original state if you need to.
This technique is especially helpful when you are "just trying different things" or editing the program while "tweaking", correcting that crucial dimension.
You can use parentheses to leave the life-line. This way you don’t have to write anything down, and documentation will remain in the program for all to see at some future date.
Example: you need to try a different value for a positioning move, so document the old amount.
G01 X4. Y4.01 (Y4.005) F20.0
By putting the old amount in your lifeline, you can easily refer to it or trace back to what you had previously used. You could even include a note specifying why you made the change.