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We're talking variations on a theme.?

Mine seems to be more elaborate, but then again, I could throw stuff at it.

/g/homebrewpcbs/album?id=86511

Harvey

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"The registration holes need to be exact, which is why I made an upside down drill press, which is far more accurate (no parallax)."

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I used a different technique to get the same benefit. FRP boards in the thickness we use are somewhat transparent, you can see the drill bit from the other side right down to the point of contact, thus no parallax, same as above. To use a normal, bench mount drill press, I purchased a single-board camera with NTSC output that I then fed into a small TV set. I built a small holder for the camera (about 1 inch cubed) plus a 45 degree angle mirror so that the debris from the drilling did not fall on the camera and cover the lens. Looking up through the hole in the center of the drill press table, I was able to position the board with one hand and lower the drill with the other. Gravity works in the same direction as drill force, so it was easy to position the board while it was resting on the table and still provide firm support against the drilling. It worked ell enough for a cheap, out-of-alignment harbor freight drill press to make accurate holes. My approach does require the extra purchase of a $40 or less mini board camera but eliminates the problem of keeping the board from falling down when not drilling or of keep the board in place against the force of drilling.

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