For clearance drill, try googling "metric free-fit drill". For the annulus, I like to be at least as large as a typical screw head. I find the catalog at mcmaster.com to have lots of representative data for hardware. Of course, mcmaster.com would be an expensive way for you to buy hardware where you live -- but the data sheets should serve you well.
-dave Michael Sokolov wrote: > Hello fellow gEDA/pcb users, > > I've got a PCB mechanical design question. I have given up on the idea > of copying the form factor of EN routers (basically I don't really like > that form factor) and I'm going for a form factor of my own. However, > being a proud citizen of the Union of Soviet Socialist Republics, I want > to make my form factor all metric -- the Soviet national standards body > required that for all new designs and my own sense of taste does the > same. :-) > > I've speced my board dimensions in metric (130x165 mm) and I'll have > mounting holes for metric screws, some M3 and some M4. My question is > about the latter: > > I've been told that the drill diameter should be 3.1 mm for an > M3-accommodating PCB hole and 4.2 mm for an M4-accommodating one; is > this correct? > > But what about the copper annulus? What would be a good copper annulus > for those screw-accommodating holes? Assume the "typical" kind of screw > used to secure PCBs to enclosures. > > TIA, > MS > > > _______________________________________________ > geda-user mailing list > geda-user@moria.seul.org > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user > > _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user