On Oct 7, 2010, at 7:50 AM, Stefan Salewski wrote: > On Thu, 2010-10-07 at 22:29 +0800, Steven Michalske wrote: >>>> I cannot get rid of the jagged diagonal lines on my design. There's lots >>>> of them. The picture shows a couple of examples. I've tried different >>>> grid sizes, line widths, but nothing fixes the problem. Redrawing them in >>>> order to eliminate any sections does not help. On PCB, it shows at some >>>> zoom levels but not others. It is in the gerbers as well and it is in the >>>> photo-mode picture I attached. >> >> >> Another thought, When I am laying out mixed pitch mm vs mil parts, I >> often leave the grid at a comfortable 10 or 25 mil setting. Turn on >> snaps to pins and pads. Then I largly ignore the grid. What I am >> saying here is that I Use the grid as a guideline. >> >> So to accomplish this I draw from the off grid pin out to the pcb and >> let the 45degree tail end on the grid. then off to the rest of the >> layout, on grid. >> >> When that tail is not quite correct, while drawing I use the u key to >> undo the 45 degree tail, this leaves the off grid stub that i can >> continue drawing from. >> >> Having a small grid usuially allows me to make a messier layout. >> > > Fine description, maybe such a text should be part of a beginner > tutorial. > >> >> If these things don't help then we have a bug..... >> > > Sure, we had bugs, and maybe some are still alive. 8 mil traces with 8 > mil clearance can be a problem due to arithmetic errors, 8 may be > rounded up to next grid position, which is 9 with 1 mil grid. (I would > use 8 mil traces, 8 mil grid and 7.9mil clearance to prevent problems) > And we had the problem of 0.01 mil traces due to arithmetic errors when > mm units are used. I guess the step to nm base units in PCB is still on > the todo list. > >
I've had perfectly explainable jaggies that occur when I am routing parallel traces. The 2nd through Nth traces of a parallel group can be pushed up against the previous traces as close as min-space, and therefore end up off-grid. This is great for routing density, but leads to a little weirdness when breaking them out again. One sources of jaggies occurs when I form a straight track with two or more segments, one that is off-grid and the new one on. Also "snap to center of pad" is often off-grid for TQFP's, etc, so that is another source of geometric oddities. I've never had a jaggie that wasn't a PEBKAC, or that couldn't be fixed by a little bit of careful editing. -dave _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
