If you have a design for a PC board that is done using some tool such as PADS, PROTEL, EAGLE (or any one of a range of choices) that then in turn outputs Gerber files for the PC board manufacturer limit the use of a Gerber post processing tool to:

A) Viewing the Gerbers to ensusure that you have the design correct.

B) Step and Repeat for panelizing.

C) Printing Gerber for use in making check plots / prints.

Under NO circumstances is it a good idea to use a Gerber editor to make changes to a PC design before you go to PCB fab. You should ALWAYS go back to the originating tool set to make any changes to the layout design.

Why you ask?

Let me say it like this. I have seen way too many instances where Rev D of a circuit board is made from the original Rev C design files say like 2 years later. (Many times even the people who did the original work are not even around). Tweaks that were made "at the last minute" by editing the Gerber files of the Rev C design before it went into production invariably never make it into the Rev D initial design!! So beware !!! If you allow Gerber files to be edited you could very end up finding that your production people are solving the same problems over again as they did 2 years before.

The only way it may be acceptable to edit Gerber files to change a design would be if one purged all original layout design files for a board before it went into manufacturing. Another similar senario is where you do not even have any original design files available and changes must be made. One place I worked had purchased a "design" from a development house and such purchased design included Gerber files, BOMs, assembly drawings, and software. This design was built for some good period of time and due to parts unavailability it was necessary to change the board artwork to accomodate a few ICs connections and foot print change. The original development house seemed to be out of business and the only choice was to either edit the Gerbers or to make a whole new layout. Seeing that the design had over 100 DIP packages it was deemed acceptable to edit the Gerbers to extract the old chips and add the new ones.

Michael Karas