I am just completing my first large scale Kicad project. This is an extremely long and narrow board with SMT parts on both sides. It was assembled by a popular Chinese concern with reps in Canada. They did a very nice job, except that all of the symmetrical 2-lead parts were put in backward (0805 photo transistors and 0805 LEDs). They fixed that issue literally overnight, but I am confused about why the .pos file did not prevent this from happening. I can only assume that a) they actually hand assembled the boards because of their odd size (26.25 x .44"), or b) there are errors in the xy file. I have carefully checked the board in pcbnew, and it looks like everything is oriented correctly and the nets are right.
I have read the great article by Rheingoldheavy, but still have questions about the orientation figure in the pos file. If a part is created in a certain orientation in the footprint editor, is that orientation considered 0 degrees in the finished board if it is put on the board in the same orientation? For instance lets say I create an 0805 LED footprint oriented like this in the editor:
cathode Cxxxxx (crude representation of the footprint, big C is pad 1 end (cathode)
So now I place this part on the board but want it vertical:
So will this part appear in the pos file as 90 degrees (or maybe 270, not sure the reference angle)? I'm not sure I get the concept of using the orientation of the part in the strip of cut tape- isn't it possible that different makers will use different tape orientation? Do some P&P machines feed from different directions, or is there a 'standard'?
This project has been an interesting learning experience, just want to get the next one letter perfect if possible.
1) be very careful to match footprint to part. There are lots of SOT3 parts but their pins and functions may differ radically! (I know, DUH).
2) when exporting to .dxf, be careful to use correct translation- apparently things default to metric so my dxf drawing was 632 inches rather than 26.25".
3) If you have a footprint/symbol error fix it early and don't let it propagate, the .fab layer symbols will be scrambled.
4) The dxf export is hard to use as an assembly drawing template- easier to just export top copper and hand draw everything else (albeit more tedious).
I hope this will save another newbie some grief.