On 5/15/07, DJ Delorie <dj@delorie.com> wrote:
Having made a number of boards at home now, I'm thinking the drill helper could be better. My local copy does this instead: If you check "drill helper", all pins are drawn with a much smaller drill hole. I.e. it doesn't draw the normal-sized hole at all, so if the drill is off-center, you won't have a gap between the hole and the copper. Instead, it only etches a small amount of copper at the center, to help you center the drill.
Following is my experience from many PCBs: With a Proxxon mini-bench drill and standard 0.8 mm drill, guiding holes are a must as the drill is so soft that it bends. The guiding hole should be smaller than the drill to work as a funnel for the drill. I use 0.5 mm holes. With a Proxxon you can litteraly see how the drill "bends" to enter the guide, and you can feel how the PCB is moved by the tension for the drill to straighten out. (We are talking about very small measures of movement and tension here) For a LABO drill or a CNC no guiding holes should be used as these drills are so hard that they will break if they hit the "edge" of the hole. They normally don't need guides anyway. With some experience, drilling with a Proxxon mini-bench is faster than using a specialized LABO for holes around 0.8 mm as a normal drill is more forgiving than the LABO one. And you also don't need to hit the hole straight as the drill "pulls" the board in. You can also re-drill a hole which is impossible with a LABO. -- Svenn _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user