Is it possible to indicate countersunk holes in the gerber files?
Currently if a board has countersunk holes, I need to indicate this in a separate drawing and send it along to the manufacturer with the gerbers.
I'm trying to figure out if a countersunk hole can be indicated through the layout software (Mentor PADS in my case) when I produce the files, or if it is even possible with the gerber format.
You should talk to your board house and discuss with them what data they need and what you can deliver for countersunk holes.
If they get a separate drawing, they have to digitize it and edit the needed NC drill files manually, but this takes time and money.
A Gerber file is data for photoplotters, but not for NC drill machines. The board house may transform a Gerber file into the needed NC drill file, but this is a manual process using their CAM CAD system and will take some time again.
A separate NC drill file for the countersunk holes only will be the best data for them, but you should discuss the details with them.
But you should be aware that countersunk holes will require additional drill jobs for the PCB, especially if both sides are countersunked. Drilling two or three boards together in a stack as usual is not possible for the countersunks, each board must be drilled separately. If you want to reduce costs, try to avoid countersunks if possible.
Understand that a Gerber file is not a manufacturing file. It is not a CNC file. It is not a PCB file. It is just a set of measurements in a standard format, that the PCB house employees will use in the process of creating their CNC files.
So yes, you can put any form of garbage in your "Gerber" files, and if you carefully explain what you want it to mean, your PCB house may be able to work out what you want the measurements to mean. Or not. It will make it more difficult for them, and they may get it wrong, and they certainly won't like you.
Gerber files are 2D + layers + apertures, and in the past, when people had no other way of specifying what they wanted, they sometimes agreed that certain "apertures" or certain "layers" would have special meaning. You will sometimes see references to that, (like this posting), where people are saying: DO NOT DO THAT. THAT IS THE PAST. IT IS NOT HELPFUL.
