In a message dated 3/24/2004 4:16:07 PM Central Standard Time,
stefan_trethan@... writes:
However i still don't see the advantage - with manual drilling it is not
easier to drill first, i would say it is even harder as you have to aim with the
same precision and you have no guiding hole.<<
ST: With the HOLES there, you can "spin" a felt-tip (Staedtler Lumocolor 313
red) in the holes, making a PERFECTLY-concentric resist-pad.
For the infrequent tiny little board with, say, no more than ONE IC and three
resistors, four terminal-pins, and one tiny capacitor, I will often use
double-stick tape and stick the layout-drawing (done on 0.1" grid "graph paper")
right to the copper. Then the drilling is easy. Particularly if you use a BP
mill with a chuck for the drill-bit in the quill, and use the index-wheels on
the X- and Y handwheels. The "drawing" and adhesive will peel right off,
pulling SOME of the dirt on the copper off with it, and then some light sanding
with 240 or 400 grit emery, wash, and . . .
I put a photo of my home-brew CNC PCB drill in the "photos" section (Nr. 15),
entitled "Home-Brew CNC PCB Drill". Using that (back when the PET was still
living!), I could REPEAT drill-patterns as accurately as "store-bought"!
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