Gerbers from EDA

You only need to make one gerber for manufacturing - boardname.gbl- the bottom layer ( solder side). When you put on the "G" it should be placed mirrored so that when it is plotted, it reads correctlly

PCB doesn't mirror gerbers; it plots all gerbers as viewed from the component side, with the same orientation.

If you ask it to *print* the layers (i.e. for home etching), it has mirroring options (auto and manual), but the (default) alignment marks include an "orientation" mark so you know which way the board is. You only get one mirror option; if you want the image rotated, just pick up the paper and rotate it ;-)

All Gerbers that I send to a board shop are as viewed from the component side of the board - even those for the solder side of the board. Any lettering I put on the board will be readable on the finished board, so lettering on the solder side is mirrored in the design program (Protel).

I can only do a true mirror (x-axis flip) which is only useful for the solder-side assembly layer documentation.

When I send stuff to the PCB house, all Gerbers are non-mirrored, i.e. all layers are viewed as shown on your monitor. Makes it easy for you to check your Gerber plots on your Gerber viewer. The PCB fabricators will probably like to see all layers as non-mirrored so they can generate netlists for their probing fixture and look for errors and design rule issues. The PCB fabricators will mirror layers as required by their process. There is no need to second guess what they require.

Doesn't apply to PCB, which can flip the board both horizontally and vertically on the monitor, plus rotate it 180 degrees.

The gerbers aren't rotated or mirrored, just the monitor.

OK; if i understand you correctly, the one side that i look at has copper and all i see is the "G" and it is called the ?bottom? layer. And from the instructions,i should tell the EDA to mirror (X mirror seems to be the presumption) for creating the gerber, and the result is non-mirrored.

So you are implying that PCB creates gerbers that are not mirrored if you do not tell it to mirror? If so, then am i correct in assuming that you get a gerber that looks eXactly what you tell it to do (*all* 4 cases)?

So Protel "automatically" mirrors the top side when it makes that gerber, but the actual file is normal reading?

That sounds ideal, but (in my EDA and it seems some others) if one does not mirror in creating the top gerber, the resulting file *is* mirrored. And don't get fussy when one tries all 4 options i mentioned as no mirror option works as one would "expect". I like things to be straight and plain; if i say "G" that is what i should get, not something that looks like a "9" or other variants that are obscene (non-creatable and non-viewable).

No, PCB doesn't create mirrored gerbers *ever*, and it doesn't give you the option to mirror them either. Why would you want to? Fabs want them all oriented the same way, *they* can mirror them if their tools want them mirrored, but how can *you* know when they need to be mirrored?

No. When working on the board layout in Protel (or most other CAD programs, I think), you are looking at the component side of the board. All the Gerber files Protel produces are also oriented as if you are looking at the component side (with X-ray vision, for the bottom and inner layers.) No mirroring involved.

When the board shop processes the Gerbers to produce their manufacturing tooling, they may mirror some layers - (I recall a requirement to have the film emulsion against the board for best resolution - don't know if that still applies, or exactly what steps the board shop uses to get from Gerber file to their tooling)

Your answer seems to be the norm. What has been frustrating, is that i have had to tell my EDA to X-mirror the top side and that resulted in a normal-reading (!) gerber. And i finally got very curious and did all 4 variations mentioned, with the gerbers never matching in any of the mirror requests. Rather messy..