Mitch Bradley wrote: > Don't worry. Many or most commercial designs these days use some parts > with metric-pitch pin layouts and others with imperial-pitch layouts. > So there is no grid that is exact for all components. That's annoying, > but it's a fact of life and people do manage to make boards that work.
I like the approach "pcb" (on Linux) uses: the cursor snaps to the grid and to the center of a pad. So you pick the grid for the spacing of traces you want, but still always end up exactly in the center of each pad/pin. Traces made from such an off-grid position still are horizontal/vertical until you lead them to a grid point at a safe distance. > And even if you were able to design on an exact metric grid, the output > device (photoplotter or printer) is quite likely to use an imperial grid > internally, so there would still be a conversion step. Ah yes, but the plotter grid is likely to be much finer than any grid I'd want to use for drawing :-) E.g., a regular laser printer with 600 dpi has a "natural" grid of 1.7 mil, while a convenient grid for manually routing 10 mil traces would be in the order of 16-25 mil. > We have had reasonable results using a .25mm grid and a .254mm (0.010") > track size. That works well for surface mount components with 0.5mm pin > pitch and also for ones with 0.050" pitch. Enter 0.8 mm TQFP :-( > As a related side topic, think how much easier things would be if the > base unit of length in the metric system had been equal to an imperial > inch. Heh, there's an interesting thought ! :-) Well, we already have mils, so it's not that far-fetched. > I am 1.88 m tall, or 6'2". It is > much easier to think about small integers than decimal fractions. 18 decimeters ? :-) Using the non-power-of-1000 SI prefixes can be dangerous, though. I think I spread eternal confusion among a generation of Linux users by introducing the decisecond as the base unit for timeouts in the LILO boot loader. Some people actually complained that the timeout somehow felt too short, not quite realizing that it was in fact off by an entire order of magnitude :-) - Werner -- _________________________________________________________________________ / Werner Almesberger, Buenos Aires, Argentina [EMAIL PROTECTED] / /_http://www.almesberger.net/____________________________________________/ Please read the Kicad FAQ in the group files section before posting your question. Please post your bug reports here. They will be picked up by the creator of Kicad. Please contribute your symbols/modules to the library folder in the group files section. For building Kicad from source and other development questions visit the kicad-devel group at http://groups.yahoo.com/group/kicad-devel Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/kicad-users/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
