Auxiliary axis & Coordinate Origin - Preparing files for fabrication. Can someone explain?

In the Pcbnew help file section “Files for fabrication” one of the outlines steps to prepare for manufacture is “Setting coordinates origin.” It mentions an auxiliary axis yet offers no explanation. I even searched the rest of the help file and there is simply tells you how to change it not what it is and why it is important. What does the phrase “one must place the auxiliary axis on this origin” mean? Which origin? On the coordinates origin?

Also, the photo included in the section sort of implies you should set this ‘coordinates origin’ to the center of a some (randomly chosen?) drill hole on your board. Does it matter where this point is actually chosen? Does the point have to be on the board?

Well, the aux axis point is set using the icon shown in the help. Where you set it is up to you, what it actually affects is the coordinates used to generate the Gerber files. I usually set it to the bottom left of my board, or the minimum extent if the board isn’t rectangular.

It might not be absolutely necessary to set the aux origin, but it is much easier when viewing the Gerbers, and perhaps easier for the fab house if your PCB is plotted near the Gerber (0,0) point (they will relocate it for the panel as necessary).

Also, I find the drill files can be aligned easily to the aux origin as well to match the PCB layers, that is quite important :slight_smile:

interesting, I always left both coordinate origins for gerber plots & drills set to absolute as to not screw up drill & copper alignment. :neutral_face:
Then naturally one has to live with the board in the gerber viewer sitting somewhere to the bottom right of the origin that that prog draws, but other viewers don’t have this problem, so yeah…

Yeah, this “Grid origin” is something that needs more explanation in the docs. I’ve posted to the developer mailing list pleading for someone to explain this.

The “auxiliary origin” can be placed anywhere on the board, and it can be selected as the Gerber/drill plot origin. In most of PCBnew, it’s called the “Drill And Place Offset,” except in the plot dialog where it’s called the “auxiliary axis” in the option “Use auxiliary axis as origin.” I put that offset at the upper-left corner of my boards.

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