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Vesa Solonen escreveu:
On Tue, 12 Jan 2010, Alain Mouette wrote:My point is exactly that there should be an option for "small mark", "50%", "100%" or simply a value for variable percentage of the "real" diameter...I see. This would be a valuable addition. Then we also need an absolute minimum too, or maybe it is better to define maximum as large drills seldom get much guiding by _copper foil_ alone? I tend to drill 1.5 mm holes as a guide for larger HSS tools.
In my experience, larger drills also have a larger central straight region. So for larger drills, maybe up to 4mm or 6mm, the center hole has to be larger too or this this central area will not fit the copper openning.
I doubt that a minimum size will be usefull for normal high speed steel drills. BUT for carbide drills I have no idea, I supose that they have a flat head, maybe a little conical, just guessing. But then the "small mark" could be usefull
Hand drilling is the most unpleasant part in proto PCB making IMHO.
Agreed, but it was not so bad with the 50% tick, using a normal stand and HSS drill.
The one machine that makes it bearable is the one available at our local amateur radio club though... I couldn't find a picture to link to, but short explanation follows. Carbide drill is fed from _below_ workpiece (solenoid + foot pedal) and operator positions the PCB by looking into a sight glass (magnifying glass + acrylic hole target). Just some very small dot is needed for sighting. Also dust is vacuumed from below. Ergonomic adjustments with tilting and about shoebox in size. Very nice or even excellent. German made if I remember right. I might took for the details some day, but this is already too much OT. Please bear with me ;)
That sounds a bit complex for the amateur to have at home... Alain
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