Another technique for getting more accurate hole drilling is to put a tiny
mirror, mounted at a 45 degree angle underneath the table of the drill
press. Then mount a small circuit board
camera<
http://www.supercircuits.com/Security-Cameras/Board-Cameras/PC302XS>for
under $20 or better yet aUSB microscope
camera<
http://www.amazon.com/Celestron-44302-Handheld-Digital-Microscope/dp/B001UQ6E4E>for
$50-60 so that the camera see the bottom side of the board you are
about to drill. Drill a few test holes and mark with thin strips of black
tape the exact point that the drill bit goes through and then you can drill
the rest of the board(s) quickly, easily, and with great precision. It is
well worth the time to tweak the mirror and camera so that the drill bit
moves EXACTLY straight up and down, because it eliminates parallax errors
when the board does not lie exactly flat on the table.
This technique should work well on any drill press where the up and down
motion is exactly lined up with the rotation of the drill bit. I think that
the Harbor Freight elcheepo bench top drill press I did this on was off by a
few degrees. It made it a little harder to guess where the drill bit would
first hit the board, and confuse you by having the last image of the drill
bit all the way through the board being offset down and right. But, if you
are no long young and don't still have 20-15 eyesight with focus from zero
to infinity, this makes precision drilling a whole lot easier.
I wish I could take credit for this, but I stole the idea from the guy
whole PCB Fab in a box.
Mike
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