A technique I've used is a little slow for a lot of holes but accurate. What I did was mount a camera to the drill-head. the camera was aimed at the board. To calibrate I drilled a hole then moved the camera over the hole. When I had a position near the center of the display, I put a dot on the screen locating the hole. I then had an offset of the dot to the drill. I could then manually position the dot over the hole then move the drill-head by the offset then drill the hole.
Roger
--- In Homebrew_PCBs@yahoogroups.com, "H. Carl Ott" <hcarlott@...> wrote:
>
> On Mon, May 24, 2010 at 9:31 AM, Mark Lerman <mlerman@...> wrote:
>
> >
> >
> >
> > The next thing would be to mount a camera on the drill so that you
> > could position the drill properly in the center of the pad. I seem to
> > remember someone doing that with software that sees the exact center
> > and helps you position correctly. Perhaps a mechanical stage. Of
> > course we're almost at cnc by then, but I think an optical aid would be
> > useful.
> >
> > Mark
> >
> >
>
> A camera system would be nice. Both for board drilling and possibly
> parts mounting.
>
> The really fancy systems (manual assist BGA pick and place) (and WAY more
> effort then it's worth for simply drilling pcb holes) use an optical beam
> splitter that slides in from the side between the target and the tool/part
> that need centering.
> The beam splitter looks BOTH up and down simultaneously, and a camera
> combines both images to help align tool and target perfectly. The optics
> then slide out of the way, and the tool does the z stroke.
>
> Now, if you could come up with a poor man's version using a couple of
> cmos webcam sensors, then maybe you would have a design worth pursuing.
> Maybe a high frame rate camera and a fast spinning mirror. Use software to
> pull out the properly referenced images you need, and combine. Before that
> point I think I'd just go CNC.
>
>
> --
> carl
> --------------------------------------------------------
> Henry Carl Ott N2RVQ hcarlott@...
>
>
> [Non-text portions of this message have been removed]
>